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Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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12 pages, 2330 KiB  
Article
Separations of Strategic Metals from Spent Electronic Waste Using “Green Methods”
by Urszula Domańska, Anna Wiśniewska and Zbigniew Dąbrowski
Separations 2025, 12(6), 167; https://doi.org/10.3390/separations12060167 - 18 Jun 2025
Viewed by 193
Abstract
Next-generation recycling technologies must be urgently innovated to tackle huge volumes of spent batteries, photovoltaic panels or printed circuit boards (WPCBs). Current e-waste recycling industrial technology is dominated by traditional recycling technologies. Herein, ionic liquids (ILs), deep eutectic solvents (DESs) and promising oxidizing [...] Read more.
Next-generation recycling technologies must be urgently innovated to tackle huge volumes of spent batteries, photovoltaic panels or printed circuit boards (WPCBs). Current e-waste recycling industrial technology is dominated by traditional recycling technologies. Herein, ionic liquids (ILs), deep eutectic solvents (DESs) and promising oxidizing additives that can overcome some traditional recycling methods of metal ions from e-waste, used in our works from last year, are presented. The unique chemical environments of ILs and DESs, with the application of low-temperature extraction procedures, are important environmental aspects known as “Green Methods”. A closed-loop system for recycling zinc and manganese from the “black mass” (BM) of waste, Zn-MnO2 batteries, is presented. The leaching process achieves a high efficiency and distribution ratio using the composition of two solvents (Cyanex 272 + diethyl phosphite (DPh)) for Zn(II) extraction. High extraction efficiency with 100% zinc and manganese recovery is also achieved using DESs (cholinum chloride/lactic acid, 1:2, DES 1, and cholinum chloride/malonic acid, 1:1, DES 2). New, greener recycling approaches to metal extraction from the BM of spent Li-ion batteries are presented with ILs ([N8,8,8,1][Cl], (Aliquat 336), [P6,6,6,14][Cl], [P6,6,6,14][SCN] and [Benzet][TCM]) eight DESs, Cyanex 272 and D2EHPA. A high extraction efficiency of Li(I) (41–92 wt%) and Ni(II) (37–52 wt%) using (Cyanex 272 + DPh) is obtained. The recovery of Ni(II) and Cd(II) from the BM of spent Ni-Cd batteries is also demonstrated. The extraction efficiency of DES 1 and DES 2, contrary to ILs ([P6,6,6,14][Cl] and [P6,6,6,14][SCN]), is at the level of 30 wt% for Ni(II) and 100 wt% for Cd(II). In this mini-review, the option to use ILs, DESs and Cyanex 272 for the recovery of valuable metals from end-of-life WPCBs is presented. Next-generation recycling technologies, in contrast to the extraction of metals from acidic leachate preceded by thermal pre-treatment or from solid material only after thermal pre-treatment, have been developed with ILs and DESs using the ABS method, as well as Cyanex 272 (only after the thermal pre-treatment of WPCBs), with a process efficiency of 60–100 wt%. In this process, four new ILs are used: didecyldimethylammonium propionate, [N10,10,1,1][C2H5COO], didecylmethylammonium hydrogen sulphate, [N10,10,1,H][HSO4], didecyldimethylammonium dihydrogen phosphate, [N10,10,1,1][H2PO4], and tetrabutylphosphonium dihydrogen phosphate, [P4,4,4,4][H2PO4]. The extraction of Cu(II), Ag(I) and other metals such as Al(III), Fe(II) and Zn(II) from solid WPCBs is demonstrated. Various additives are used during the extraction processes. The Analyst 800 atomic absorption spectrometer (FAAS) is used for the determination of metal content in the solid BM. The ICP-OES method is used for metal analysis. The obtained results describe the possible application of ILs and DESs as environmental media for upcycling spent electronic wastes. Full article
(This article belongs to the Section Materials in Separation Science)
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27 pages, 3488 KiB  
Review
Current Perspectives on the Extraction, Isolation, and Identification of Fats and Fatty Acids Using Conventional and Green Methods
by Ytaiara Lima-Pereira, Esther Maria Oliveira de Souza, David Silva dos Reis, Ian Gardel Carvalho Barcellos-Silva, Karine Sayuri Lima Miki, Valdir F. Veiga-Júnior and Barbara Elisabeth Teixeira-Costa
Separations 2025, 12(6), 160; https://doi.org/10.3390/separations12060160 - 13 Jun 2025
Viewed by 401
Abstract
The global demand for oils and lipids, particularly those derived from vegetable sources with high polyunsaturated fatty acid content, has posed significant challenges for the food industry. This trend is largely driven by growing consumer awareness of health and nutrition. To meet this [...] Read more.
The global demand for oils and lipids, particularly those derived from vegetable sources with high polyunsaturated fatty acid content, has posed significant challenges for the food industry. This trend is largely driven by growing consumer awareness of health and nutrition. To meet this demand, it is essential to not only identify richer sources of lipids but also develop efficient, sustainable, and environmentally friendly methods for their extraction, isolation, and characterization. In this context, the present work provides a comprehensive review of current perspectives on the extraction, isolation, and identification of lipids and fatty acids, comparing conventional and green methodologies for food applications. Ideally, analytical and processing methodologies for obtaining food-grade materials should prioritize low energy consumption, minimal or no use of hazardous substances, and the generation of non-polluting residues, thereby safeguarding both human health and the environment. In recent years, green extraction techniques have emerged as promising alternatives to conventional methods, offering partial or complete replacements, such as ultrasound-assisted extraction, microwave-assisted extraction, supercritical and subcritical fluid extraction, and others. However, significant advancements are still required to fully address these concerns. Techniques such as chromatography and spectrometry play pivotal roles in the isolation and identification process, especially gas chromatography coupled with mass spectrometry or with flame ionization detectors; while separating individual fatty acids based on their chain length and degree of unsaturation, reversed-phase high-performance liquid chromatography (HPLC) is quite a helpful approach. Furthermore, the isolation and structural elucidation of fatty acids are critical steps in ensuring the nutritional quality and commercial viability of lipid products. Full article
(This article belongs to the Special Issue Extraction and Characterization of Food Components)
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16 pages, 1616 KiB  
Article
Comparison of Extraction Techniques for Wide Screening of 230 Pesticides in Water
by Caterina Cacciatori, Jackie Myers, Giulio Mariani, Hung Vu, Bernd Manfred Gawlik and Vincent Pettigrove
Separations 2025, 12(6), 158; https://doi.org/10.3390/separations12060158 - 9 Jun 2025
Viewed by 296
Abstract
In this study, weekly grab samples extracted by solid-phase extraction (SPE) and stir bar sorptive extraction (SBSE) were compared for the analysis of 230 pesticides in surface waters. Samples were collected from three different locations around Melbourne, Australia. Analysis was performed using Gas [...] Read more.
In this study, weekly grab samples extracted by solid-phase extraction (SPE) and stir bar sorptive extraction (SBSE) were compared for the analysis of 230 pesticides in surface waters. Samples were collected from three different locations around Melbourne, Australia. Analysis was performed using Gas Chromatography Quadrupole Time of Flight High Resolution Mass Spectrometry (GC-QToF-HRMS). The two extraction techniques were compared, among others, for their limits of detection, recovery, extraction, and quantification efficiency of pesticides, as well as spatial and temporal differences in detected compounds. The target compounds screened were pesticides belonging mainly to the categories of fungicides, insecticides, and herbicides. Although SBSE extracted more pesticides at two out of three sites, SPE extracted total concentrations up to four times higher than SBSE over all sampling sites. The log KOW of detected pesticides only partially explained the differences in detection, with SBSE performing better in the absorption of hydrophobic compounds. In addition, matrix effects, in particular turbidity, appeared to hinder extraction of contaminants, especially for SBSE. Spatially, SBSE detected 10 pesticides more than SPE at two locations, while the opposite was true at the third location, where turbidity was higher. The types of pesticides detected varied slightly between techniques and locations. The study highlights the complementarity of SBSE and SPE for monitoring pesticides in natural environments. SBSE is an easy-to-use technique and allows for extraction of a higher number of pesticides at trace level, but it might not be the preferred option for highly turbid waters. SPE requires more tedious and complex sample processing but allows for a more accurate quantification of a broader range of pesticides. Full article
(This article belongs to the Special Issue New Techniques for Extraction and Removal of Pesticide Residues)
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13 pages, 1875 KiB  
Article
Development and Validation of a Method for the Analysis of Multiple Pesticides in Fishery Products Using Gas Chromatography with Micro-Electron Capture Detection and Gas Chromatography–Tandem Mass Spectrometry
by Myungheon Kim, Mihyun Cho, Changkyo Seo, Jaebin Im, Changhyeon Park, Yoonmi Lee, Mi-Ra Jo, Yong-Sun Moon and Moo-Hyeog Im
Separations 2025, 12(6), 142; https://doi.org/10.3390/separations12060142 - 28 May 2025
Viewed by 228
Abstract
This study aims to develop a simultaneous analytical method for detecting 19 pesticides, including 4,4′-DDD, in fishery products using gas chromatography with micro-electron capture detection (GC-μECD) and gas chromatography–tandem mass spectrometry (GC-MS/MS). A new analytical method was developed to measure pesticide residues in [...] Read more.
This study aims to develop a simultaneous analytical method for detecting 19 pesticides, including 4,4′-DDD, in fishery products using gas chromatography with micro-electron capture detection (GC-μECD) and gas chromatography–tandem mass spectrometry (GC-MS/MS). A new analytical method was developed to measure pesticide residues in fishery products based on the modified Association of Official Analytical Chemists protocol combining quick, easy, cheap, effective, rugged, and safe (QuEChERS) and the Pesticide Analytical Manual for extraction and purification. Extraction was performed using acetonitrile containing 0.1% acetic acid, and purification was conducted with Florisil cartridges. The Florisil cartridges were more effective than QuEChERS in removing impurities and pigments during purification and also resulted in a reduced matrix effect. The validation followed Codex guidelines (CAC/GL 40). The limit of detection ranged from 2 to 3 ng/g, and the limit of quantification (LOQ) from 7 to 10 ng/g. Matrix-matched calibration curves exhibited linearity with coefficients of determination exceeding 0.99 for all target analytes. Accuracy was assessed based on recovery rates, while precision was evaluated using relative standard deviations (RSD) at three spiking levels (LOQ, 10×LOQ, and 50×LOQ). The recovery rates ranged from 62.6 to 119.1%, with RSDs of 0.4 to 19.5%, conforming to Codex guidelines. Full article
(This article belongs to the Special Issue Chemical and Contaminant Residue Analysis via Chromatography)
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14 pages, 815 KiB  
Article
Mixed-Mode Chromatography: Studies on Hybrid Retention Mechanisms of Some Antihypertensive Drugs
by Irinel Adriana Badea, Andrei Mihăilă, Dana Elena Popa, Anca Monica Tencaliec and Mihaela Buleandră
Separations 2025, 12(6), 136; https://doi.org/10.3390/separations12060136 - 22 May 2025
Viewed by 233
Abstract
The antihypertensive drugs indapamide, atenolol, metoprolol, propranolol and bisoprolol were considered in this research. Because they have structures that are affected by pH, developing a chromatographic method was challenging. Based on the speciation diagram of these compounds versus pH scale, a mixed-mode stationary [...] Read more.
The antihypertensive drugs indapamide, atenolol, metoprolol, propranolol and bisoprolol were considered in this research. Because they have structures that are affected by pH, developing a chromatographic method was challenging. Based on the speciation diagram of these compounds versus pH scale, a mixed-mode stationary phase (hydrophobic stationary phase, C18 and strong cation exchanger (SCX)) was our first choice. Design of Experiments (DoE) was used to estimate how various factors such as pH, mobile phase composition and flow rate influenced chromatographic performance. As a result, the separation was achieved in 24 min using an aqueous phosphate buffer phase (pH 7.20) and 20 mM triethylamine, with methanol being used as organic modifier (30%). Their retention mechanism was investigated. The new method was validated in term of linearity, limits of detection and quantification, precision, accuracy, and robustness. The method was applied to river water samples, and good results were obtained. Full article
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18 pages, 3393 KiB  
Article
Development of a High-Performance Immunoaffinity Separation Technique for Rare Cell Capture
by Dora Szerenyi, Paul Stolk, Jozsef Tovari, Laszlo Takacs and Andras Guttman
Separations 2025, 12(5), 134; https://doi.org/10.3390/separations12050134 - 20 May 2025
Viewed by 358
Abstract
Circulating tumor cell enrichment and enumeration are advancing early detection of cancer, monitoring of therapy response, and even next-generation therapies. Efficiently capturing rare cells from complex biological fluids is essential in both diagnostic and therapeutic applications. EpCAM-positive tumor cells are specifically captured by [...] Read more.
Circulating tumor cell enrichment and enumeration are advancing early detection of cancer, monitoring of therapy response, and even next-generation therapies. Efficiently capturing rare cells from complex biological fluids is essential in both diagnostic and therapeutic applications. EpCAM-positive tumor cells are specifically captured by utilizing covalently immobilized anti-EpCAM monoclonal antibodies onto the surface of chemically modified glass microbeads. To maximize the capture efficiency, bead geometry, immobilization conditions, flow rate, and anticoagulant dosage were systematically optimized. An in vitro flow-capture system was designed and used to evaluate the capture efficiency of the proposed technology by utilizing HTC116 colon cancer cell-spiked model media. The effect of substrate surface pretreatment was characterized by goniometry, while the capture performance was monitored by flow cytometry and fluorescent microscopy. The specific capture ability of the bioactive microbead substrate reached over 130,000 cells in the laboratory-scale cartridge (V(cartridge) = 2.6 cm3; m(bead) = 4 g). This capture efficiency suggests a promising rare-cell capture utilization of the proposed technology and may be used for research, diagnostic, and therapeutic purposes. In this paper, we reported on the development and feasibility test of a high-performance bioactive glass-microbead cell capture substrate. Due to the relevance and novelty of the reported results, with further development, the versatile platform technology presented could be readily implemented to capture tumor cells from complex biological samples and represent an additional complementary tool to existing cancer diagnostics and therapies. Full article
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24 pages, 1664 KiB  
Review
Microextraction and Eco-Friendly Techniques Applied to Solid Matrices Followed by Chromatographic Analysis
by Attilio Naccarato, Rosangela Elliani and Antonio Tagarelli
Separations 2025, 12(5), 124; https://doi.org/10.3390/separations12050124 - 14 May 2025
Viewed by 459
Abstract
In this review, a 5-year overview on environmentally friendly approaches for the extraction of the most relevant organic pollutants in soil, sediment, particulate matter, and sewage sludge coupled with chromatographic analysis is reported. Organic contaminants encompass various compounds derived from personal care products, [...] Read more.
In this review, a 5-year overview on environmentally friendly approaches for the extraction of the most relevant organic pollutants in soil, sediment, particulate matter, and sewage sludge coupled with chromatographic analysis is reported. Organic contaminants encompass various compounds derived from personal care products, industrial chemicals, microplastics, organic matter combustion, agricultural practices, and plasticizer material. The principles of green analytical chemistry (GAC) and green sample preparation (GSP) serve as a guideline for the development of more environmentally sustainable analytical protocols. This study focuses attention on microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), matrix solid-phase dispersion (MSPD), and microextraction techniques, such as solid-phase microextraction (SPME), stir bar sorptive extraction (SBSE), hollow-fiber liquid-phase microextraction (HF-LPME), spray-assisted droplet formation-based liquid-phase microextraction (SADF-LPME), and dispersive liquid–liquid extraction (DLLME). These approaches represent the most relevant eco-friendly sample preparation for the advanced extraction of target analytes from environmental solid samples. Full article
(This article belongs to the Special Issue Sample Preparation and Chromatographic Analysis of Environmental Samples)
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11 pages, 1447 KiB  
Article
Development and Validation of a Sensitive LC-MS/MS Method for the Determination of N-Nitroso-Atenolol in Atenolol-Based Pharmaceuticals
by Soonho Kwon, Sang-Hyun Ahn, Yongha Chang, Joon-Sang Park, Hwangeui Cho and Jung-Bok Kim
Separations 2025, 12(5), 122; https://doi.org/10.3390/separations12050122 - 12 May 2025
Viewed by 544
Abstract
The recent detection of N-nitroso-atenolol, a mutagenic and potentially carcinogenic impurity in atenolol-based pharmaceuticals, has raised serious safety concerns and emphasized the need for stringent analytical control. This study developed and validated a highly sensitive LC-MS/MS method for quantifying N-nitroso-atenolol in both active [...] Read more.
The recent detection of N-nitroso-atenolol, a mutagenic and potentially carcinogenic impurity in atenolol-based pharmaceuticals, has raised serious safety concerns and emphasized the need for stringent analytical control. This study developed and validated a highly sensitive LC-MS/MS method for quantifying N-nitroso-atenolol in both active pharmaceutical ingredients (APIs) and finished products. Quantification was carried out using multiple reaction monitoring (MRM) under positive-mode electrospray ionization (ESI). Separation was performed on a C18 reversed-phase column with a gradient of water and methanol containing 0.1% formic acid. The method was validated to meet a specification limit of 15 ng/mg, with a linear range of 0.5–80 ng/mL, effectively covering 10–400% of the regulatory threshold. The method exhibited an excellent performance in terms of specificity, accuracy, precision, linearity, and robustness. It achieved a limit of detection (LOD) of 0.2 ng/mL (0.30 ng/mg) and a limit of quantification (LOQ) of 0.5 ng/mL (0.75 ng/mg), alongside a comprehensive uncertainty analysis with an expanded uncertainty of ±3.86 mg/kg. Application to commercial atenolol products confirmed the reliability and practical utility of the method. This validated approach offers a critical tool for pharmaceutical manufacturers and regulatory agencies to monitor and control N-nitroso-atenolol, ensuring compliance and enhancing patient safety. Full article
(This article belongs to the Section Analysis of Natural Products and Pharmaceuticals)
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17 pages, 2794 KiB  
Article
Defluoridation of Water Using Al-Mg-Ca Ternary Metal Oxide-Coated Sand in Adsorption Column Study
by Kiana Modaresahmadi, Amid P. Khodadoust and James Wescott
Separations 2025, 12(5), 119; https://doi.org/10.3390/separations12050119 - 7 May 2025
Viewed by 377
Abstract
Defluoridation of water was investigated in an adsorption column study using Al-Mg-Ca-coated sand (AMCCS), a ternary metal oxide adsorbent with eco-friendly components that were shown to be effective for water defluoridation, in a batch adsorption study. A packed column of the AMCCS sorbent [...] Read more.
Defluoridation of water was investigated in an adsorption column study using Al-Mg-Ca-coated sand (AMCCS), a ternary metal oxide adsorbent with eco-friendly components that were shown to be effective for water defluoridation, in a batch adsorption study. A packed column of the AMCCS sorbent was evaluated as function of column flow rate, solution type, and sorbent recyclability. Adsorption column experiments included two column flow rates of 2 mL/min and 10 mL/min using two different solutions: deionized water and a synthetic solution representative of groundwater. Greater fluoride column adsorption capacity was obtained at the lower flow rate for both solutions, mainly due to longer contact times between solution and AMCCS sorbent. Adsorption of fluoride occurred through physical adsorption, which followed the Langmuir adsorption model and second-order kinetics for deionized water and synthetic solution. A lower AMCCS column fluoride adsorption capacity was observed for the synthetic solution due to the competition from adsorption of other ions in the synthetic solution, whereas fluoride adsorption by the AMCCS column was influenced by interphase mass transfer to a lesser extent using the synthetic solution than deionized water. The re-coating of spent AMCCS sorbent in the adsorption column resulted in effective recycling and reuse of the AMCCS adsorption column for both deionized water and the synthetic solution, rendering the AMCCS adsorption column a recyclable and sustainable flow through water defluoridation system. Full article
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17 pages, 2019 KiB  
Article
Free Fatty Acid Determination in Alcoholic and Non-Alcoholic Beers via Liquid Chromatography–High-Resolution Mass Spectrometry Analysis
by Christiana Mantzourani and Maroula G. Kokotou
Separations 2025, 12(5), 114; https://doi.org/10.3390/separations12050114 - 1 May 2025
Viewed by 1756
Abstract
In recent years, non-alcoholic beers have been gaining popularity. Among the various components that affect the flavor and sensory characteristics of beers, free fatty acids (FFAs) are minor components. However, due to their involvement in beer quality, fast and simple methods for analyzing [...] Read more.
In recent years, non-alcoholic beers have been gaining popularity. Among the various components that affect the flavor and sensory characteristics of beers, free fatty acids (FFAs) are minor components. However, due to their involvement in beer quality, fast and simple methods for analyzing FFAs in beers are of importance. In this work, we present a liquid chromatography–high-resolution mass spectrometry (LC-HRMS) method for the rapid determination of FFAs in beers, avoiding a tedious sample preparation and derivatization and allowing the simultaneous study of a large set of FAs, including medium-chain, long-chain, saturated, monounsaturated and polyunsaturated FAs. The method was applied in the analysis of twelve non-alcoholic and nine alcoholic beer samples from the local market, permitting the comparison of their FFA profiling. Among the 37 FAs studied, 29 were quantified, and palmitic, stearic, oleic and myristic acids were identified as the predominant FAs in both alcoholic and non-alcoholic beers. The majority of the predominant long-chain FAs, including palmitic, stearic and myristic acids, were found in decreased amounts in non-alcoholic beers, compared to the alcoholic ones, with the marked exception of oleic acid, which was increased in non-alcoholic beers. Among the medium-chain FAs, octanoic acid was found at lower concentrations in non-alcoholic beers, comparing to regular beers, while lauric acid was slightly increased. Principal component analysis (PCA) suggested the correlation of FFAs with the type of beer (alcoholic or non-alcoholic beer). Full article
(This article belongs to the Special Issue Chromatography/Mass Spectrometry for the Determination of Food Authenticity and Food Analysis)
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17 pages, 3618 KiB  
Article
Polymer-Coated Nickel Nanoparticles for CO2 Capture in Seawater
by Abhishek, Abhishek Ratanpara, Adib Mahmoodi Nasrabadi and Myeongsub Kim
Separations 2025, 12(5), 107; https://doi.org/10.3390/separations12050107 - 24 Apr 2025
Viewed by 628
Abstract
Carbon capture and storage (CCS) technologies are employed to mitigate global warming by removing carbon from the atmosphere. To enhance carbon capture efficiency, nanoparticles have gained considerable attention as catalysts due to their large surface area, tunable properties, regeneration, and enhanced reactivity. However, [...] Read more.
Carbon capture and storage (CCS) technologies are employed to mitigate global warming by removing carbon from the atmosphere. To enhance carbon capture efficiency, nanoparticles have gained considerable attention as catalysts due to their large surface area, tunable properties, regeneration, and enhanced reactivity. However, it poses some challenges, such as nanoparticle aggregation and reduced effectiveness in sustainable solvents like seawater. To address these limitations and promote an environmentally sustainable method for carbon capture, this study evaluates the CO2 capture efficiency of seawater using nickel nanoparticles (NiNPs) coated with polyvinylpyrrolidone (PVP) as a catalyst. We examined the time-dependent size variations of CO2 bubbles in a flow-focusing microchannel using high-speed bubble-based microfluidics, directly associated with transitory CO2 dissolution into the surrounding solution. We hypothesized that smaller polymer-coated NiNPs, due to their higher surface-to-volume ratio, can enhance CO2 solubility and capture rates under identical environmental conditions. To verify this, polymer-coated NiNPs of three different sizes—5 nm, 10 nm, and 20 nm—were synthesized and tested. The experiments revealed that 5 nm NiNPs achieved a CO2 dissolution rate of 77%, in contrast to 71% for 10 nm and 43% for 20 nm particles. These findings validate the hypothesis, demonstrating that smaller nanoparticles facilitate more effective CO2 capture using equivalent material quantities, thereby potentially improving the overall efficiency of CO2 reduction. This innovative approach contributes to advancing NiNP-based catalysts for saltwater-based CO2 capture. Full article
(This article belongs to the Special Issue Application of Advanced Materials and Technologies in the Separation and Adsorption)
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15 pages, 2586 KiB  
Article
Enhanced Selective Separation of Pu(IV) and U(VI) Using Novel Diethylene Glycolamide Ligand
by Xiaoyun Guo, Junli Wang, Yao Liu, Haojun Zhao, Hui Wang, Wentao Wang, Baole Li and Taihong Yan
Separations 2025, 12(5), 106; https://doi.org/10.3390/separations12050106 - 23 Apr 2025
Viewed by 333
Abstract
Developing a new efficient separation ligand based on the “CHON” principle to address the limitations of phosphorus containing extractants in nuclear fuel reprocessing can help further simplify the process flow and reduce the amount of secondary waste. Building upon this critical need, a [...] Read more.
Developing a new efficient separation ligand based on the “CHON” principle to address the limitations of phosphorus containing extractants in nuclear fuel reprocessing can help further simplify the process flow and reduce the amount of secondary waste. Building upon this critical need, a novel ligand was developed through a strategic application of the Hard and Soft Acids and Bases (HSAB) theory, integrating a soft donor nitrogen atom into the linear architecture of bis-diglycolamide. This groundbreaking ligand, named N,N′-bis[2-(2-(N,N-dioctylcarbamoyl)ethoxy)ethylacetamido]-N″-diethylenetriamine (TOMDEA-BisDGA), has demonstrated remarkable potential in the extraction of Pu(IV). The study unveils that the ligand demonstrates remarkable selectivity and separation efficiency towards Pu(IV) ions while maintaining an exceptionally low extraction capacity for U(VI) across a wide acidity spectrum of 0.1~6 mol/L. To explain the structure properties of complex formed by the ligand and Pu(IV), a systematic analysis was performed, including slope analysis, proton nuclear magnetic resonance (NMR) titration, and Fourier-transform infrared (FT-IR) spectroscopy. This study explores the coordination and separation behavior of diglycolamide ligands with actinide. This work is expected to provide important information and theoretical bases upon which advanced design and optimization of ligands for high-performance processes for the separation of plutonium might be carried out. Such findings will contribute to the understanding of actinide chemistry and further the design of improved separation methods for nuclear applications. Full article
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23 pages, 527 KiB  
Review
New Trends in the Methodologies of Determination of Benzodiazepine Residues in Biological Samples
by Israel S. Ibarra, Isaí Vázquez-Garrido, Gabriela Islas and Juan F. Flores-Aguilar
Separations 2025, 12(4), 95; https://doi.org/10.3390/separations12040095 - 11 Apr 2025
Viewed by 722
Abstract
The benzodiazepines are essential drugs used in medicine for anxiolytic, sedative, and hypnotic effects. According to the World Health Organization, the benzodiazepines are the most prescribed hypnotic drugs in the last decade (2010 at time), and their inappropriate use can damage the environment [...] Read more.
The benzodiazepines are essential drugs used in medicine for anxiolytic, sedative, and hypnotic effects. According to the World Health Organization, the benzodiazepines are the most prescribed hypnotic drugs in the last decade (2010 at time), and their inappropriate use can damage the environment and human health. The availability of efficient analytical methods is crucial for the determination of these drugs in a complex matrix such as biological samples in clinical settings. In the last decade, several methods have been developed and have been applied to the detection and determination of benzodiazepines or their derivates. The present manuscript reviews selective and sensitive methodologies based on chromatographic, electrophoretic, and electrochemical systems for the determination of benzodiazepines in biological samples, covering the time of the last years and providing detailed information on sample pretreatment and instrumental conditions. Full article
(This article belongs to the Section Bioanalysis/Clinical Analysis)
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16 pages, 2875 KiB  
Article
Extraction and Characterization of TiO2 Pigments from Commercial Paints for Environmental Studies
by Allan Philippe, Sylvester Ndoli-Kessie, Christian Fricke, Jean-Michel Guigner, Benjamin Heider and Eliana Di Lodovico
Separations 2025, 12(4), 91; https://doi.org/10.3390/separations12040091 - 8 Apr 2025
Viewed by 600
Abstract
TiO2 nanoparticles are found as pigments in coatings and paints and are, therefore, released into the environment through runoff. To assess their environmental impact, comprehensive fate and ecotoxicity studies necessitate particles closely resembling those released into the environment. In response, we developed [...] Read more.
TiO2 nanoparticles are found as pigments in coatings and paints and are, therefore, released into the environment through runoff. To assess their environmental impact, comprehensive fate and ecotoxicity studies necessitate particles closely resembling those released into the environment. In response, we developed a method designed to isolate TiO2 particles from commercial paints. Using six contrasting paints alongside a pure TiO2 pigment, we evaluated two extraction methods in terms of recovery, purification rate, and preservation of both inorganic and organic particle coatings. The paints and extracts were characterized using cryogenic-TEM, ICP-OES, thermogravimetry, and infrared spectroscopy. In contrast to the alkaline-based extraction method, the extraction with acetic acid facilitated the retention of both inorganic and organic coatings and ensured good removal of organic polymers. Recovery rates exceeded 70% for all paints and extraction methods, yet the complete removal of SiO2, when present, was not achieved. CaCO3 removal was effective with both extraction methods. Our developed extraction method enables the isolation of TiO2-particles similar to those aged within paints. However, we recommend using silicate-free paints when SiO2 interference is of concern for the study design. Furthermore, this method could be interesting for pigment recycling, offering a gentler alternative to existing techniques which compromise particle coatings. Full article
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23 pages, 11856 KiB  
Review
Microplastics in the Environment: A Review Linking Pathways to Sustainable Separation Techniques
by Lin Zeng, Long Li, Jueyan Xiao, Penghui Zhou, Xiaoxiang Han, Bohao Shen and Li Dai
Separations 2025, 12(4), 82; https://doi.org/10.3390/separations12040082 - 30 Mar 2025
Viewed by 974
Abstract
Since the mid-20th century, the quantity of microplastics (MPs) has increased significantly, becoming a persistent environmental pollutant widely distributed in global water bodies, soils, and the atmosphere. While plastic materials have brought significant convenience to daily life, the MPs resulting from their degradation [...] Read more.
Since the mid-20th century, the quantity of microplastics (MPs) has increased significantly, becoming a persistent environmental pollutant widely distributed in global water bodies, soils, and the atmosphere. While plastic materials have brought significant convenience to daily life, the MPs resulting from their degradation pose increasing threats to ecosystems and human health. This comprehensive review examines the sources, migration pathways, and ecological impacts of MPs, and critically evaluates the current separation techniques from physical, chemical, and biological perspectives. In particular, numerical simulations of the hydrocyclone separation technique reveal its unique flow characteristics, including turbulent velocity gradients and axial pressure differences, with a separation efficiency of up to 93%. This technique offers advantages such as high efficiency, low energy consumption, and environmental friendliness. In response to the growing microplastic pollution issue, this review emphasizes that the development of future microplastic separation techniques should prioritize separation efficiency, sustainability, and environmental compatibility. Continued research in this field will provide theoretical support for optimizing microplastic pollution control technologies and contribute to achieving environmental protection and sustainable development goals. Full article
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8 pages, 1590 KiB  
Article
Separation of D-Amino Acid-Containing Tripeptide L-Asn-D-Trp-L-Phe-NH2 and Its Diastereomer Using Crown–Ether-Type Chiral Stationary Phase
by Batsaikhan Mijiddorj, Yohei Kayano, Hiroki Yamagishi, Haruto Nakajima and Izuru Kawamura
Separations 2025, 12(3), 67; https://doi.org/10.3390/separations12030067 - 10 Mar 2025
Viewed by 680
Abstract
Several D-amino acid residue-containing peptides (DAACPs) with antimicrobial, cardio-excitatory, and neuronal activities have been identified in various species. The L-Asn-D-Trp-L-Phe-NH2 (N(dW)F) tripeptide, derived from Aplysia kurodai, exhibits cardiac activity in invertebrates. The chirality of the tryptophan residue at the second position [...] Read more.
Several D-amino acid residue-containing peptides (DAACPs) with antimicrobial, cardio-excitatory, and neuronal activities have been identified in various species. The L-Asn-D-Trp-L-Phe-NH2 (N(dW)F) tripeptide, derived from Aplysia kurodai, exhibits cardiac activity in invertebrates. The chirality of the tryptophan residue at the second position in N(dW)F influences its conformation and biological characteristics. We demonstrated the chiral separation of N(dW)F and its diastereomer NWF using (S)-3,3′-diphenyl-1,1′-binaphthyl-20-crown-6-ether columns (CR-I(+)). A reduction in the ratio of acetonitrile and methanol in the mobile phase allowed the complete separation of N(dW)F and its diastereomer, improving the separation factor (α) from 0.96 to 6.28. Molecular dynamics simulations revealed that the interaction of N(dW)F with CR-I(−) was more favorable than with CR-I(+). These findings indicate that the structure of the CR-I column stereoselectively recognizes peptides and facilitates the separation of naturally occurring D-amino acid residue-containing tripeptides. Full article
(This article belongs to the Special Issue Peptide Synthesis, Separation and Purification)
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12 pages, 1419 KiB  
Review
A Brief Overview of Nanomaterials in Inorganic Selenium Speciation
by Krystyna Pyrzynska
Separations 2025, 12(3), 64; https://doi.org/10.3390/separations12030064 - 9 Mar 2025
Viewed by 588
Abstract
Although total selenium content is still useful in many areas, knowledge of its speciation is gaining importance as its various chemical forms have different environmental effects, toxicities and biological utilization. Among several methods used for the isolation and enrichment of selenium species, solid-phase [...] Read more.
Although total selenium content is still useful in many areas, knowledge of its speciation is gaining importance as its various chemical forms have different environmental effects, toxicities and biological utilization. Among several methods used for the isolation and enrichment of selenium species, solid-phase extraction and its alternative approaches are often applied due to their simplicity and high efficiency. This brief overview summarizes the progress made in using different nanostructure sorbents to separate and preconcentrate inorganic selenium species in environmental waters. Nanomaterials are finding increasing applications as they have a large specific surface area and high chemical stability. Functionalizing their surface by covalent or noncovalent interactions with other components, grafting or doping with heteroatoms can improve the separation and removal efficiency. Strategies based on combining selective chemical reactions and separation procedures are discussed. Full article
(This article belongs to the Special Issue Environmental Functional Nanomaterials in Heavy Metal Removal and Pollutant Degradation)
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13 pages, 3079 KiB  
Article
The Bio-Desulfurization of Cassiterite–Polymetallic Sulfide Ores Enhanced by a Consortium of Moderately Thermophilic Bacteria
by Mingwei Wang, Weimin Zeng, Zhen Yan, Li Shen, Runlan Yu, Xueling Wu, Jiaokun Li, Guanzhou Qiu, Wolfgang Streit and Yuandong Liu
Separations 2025, 12(3), 61; https://doi.org/10.3390/separations12030061 - 6 Mar 2025
Viewed by 508
Abstract
Sulfides should be removed before the recovery of cassiterite from tin-rich minerals due to their similarity in flotation properties. However, the traditional methods used have low selectivity. Therefore, moderately thermophilic microorganisms were used to desulfurize tin ore in this study, and the success [...] Read more.
Sulfides should be removed before the recovery of cassiterite from tin-rich minerals due to their similarity in flotation properties. However, the traditional methods used have low selectivity. Therefore, moderately thermophilic microorganisms were used to desulfurize tin ore in this study, and the success of the microbial community was investigated. The bio-desulfurization rate reached 90% on the 10th day using the mixed culture of Leptospirillum ferriphilum (L. ferriphilum), Sulfobacillus thermosulfidooxidans (S. thermosulfidooxidans), and Acidithiobacillus caldus (A. caldus), while the pure culture needs at least 14 days. The results of X-ray Diffraction (XRD) and Inductively Coupled Plasma show that the sulfides were nearly fully solubilized. XRD results showed no pyrite in the residue, indicating that pyrite was almost fully removed while cassiterite was enriched compared with the original minerals. The high-throughput sequencing analysis showed that S. thermosulfidooxidans were the predominant species during the early bioleaching period, and L. ferriphilum were the predominant species in the following period. A. caldus is consistently detected and accounts for 30–50% of the different growth stages. This study supplied a potentially practical application for the desulfurization in tin ore. Full article
(This article belongs to the Section Purification Technology)
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43 pages, 8193 KiB  
Review
From Waste to Wealth: A Circular Economy Approach to the Sustainable Recovery of Rare Earth Elements and Battery Metals from Mine Tailings
by Mohammed Omar Sahed Chowdhury and Deniz Talan
Separations 2025, 12(2), 52; https://doi.org/10.3390/separations12020052 - 14 Feb 2025
Cited by 2 | Viewed by 4387
Abstract
The increasing global demand for critical minerals, driven by rapid population growth and the widespread adoption of low-carbon technologies, electric vehicles, and clean energy systems, highlights the urgent need for sustainable resource management. Mine tailings, traditionally considered waste, are now being recognized as [...] Read more.
The increasing global demand for critical minerals, driven by rapid population growth and the widespread adoption of low-carbon technologies, electric vehicles, and clean energy systems, highlights the urgent need for sustainable resource management. Mine tailings, traditionally considered waste, are now being recognized as valuable secondary sources for mineral recovery. This paper compiles a comprehensive review of the four short- and mid-term critical minerals (lithium, cobalt, nickel, and rare earth elements) and provides insights regarding their recovery with a focus on the latest technological advancements. By exploring key innovations in separation processes, the review demonstrates how these technologies are addressing supply chain bottlenecks while simultaneously reducing the environmental footprint of mining operations. The paper also advocates for a holistic approach to mine waste management, integrating mineral recovery with environmental remediation. It emphasizes the dual benefits of recovering valuable resources while purifying contaminated water and mitigating pollution risks. The proposed circular economy model suggests a sustainable blueprint for managing mine tailings, emphasizing resource reuse, waste reduction, and economic viability. Full article
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10 pages, 1639 KiB  
Article
Detection of Honey Adulteration by Liquid Chromatography—High-Resolution Mass Spectrometry: Results from an EU Coordinated Action
by Viviana Paiano, Andreas Breidbach, Carolin Lörchner, Tereza Ždiniaková, Olivier De Rudder, Alain Maquet, Lourdes Alvarellos and Franz Ulberth
Separations 2025, 12(2), 47; https://doi.org/10.3390/separations12020047 - 13 Feb 2025
Cited by 2 | Viewed by 3409
Abstract
Honey, a sweet and nutritious food produced by honeybees, is extensively consumed by humans due to its potential health benefits. Unfortunately, the adulteration of honey with inexpensive sugar syrups is a prevalent issue. Verifying the authenticity of honey is crucial for maintaining its [...] Read more.
Honey, a sweet and nutritious food produced by honeybees, is extensively consumed by humans due to its potential health benefits. Unfortunately, the adulteration of honey with inexpensive sugar syrups is a prevalent issue. Verifying the authenticity of honey is crucial for maintaining its quality and safety standards. The aim of this study was to identify the illicit addition of sugar syrups to honey imported into the European Union (EU). The European Commission’s Joint Research Centre (JRC) has employed different analytical approaches to detect several markers of adulteration in honey; however, this paper mainly focuses on the use of Liquid Chromatography–High-Resolution Mass Spectrometry (LC-HRMS). Two qualitative methods were developed to detect mannose (Man), difructose anhydride III (DFA III), 2-acetylfuran-3-glucopyranoside (AFGP), and oligo-/polysaccharides with degrees of polymerization (DPs) of 6 to 11. Out of the 320 honey samples provided by the authorities of the participating EU Member States, 147 (46%) were suspicious for non-compliance with the EU Honey Directive 2001/110/EC, mostly due to the presence of mannose and oligo-/polysaccharides. As a result, the development and standardization of sophisticated and universally recognized testing procedures will increase the capability of official control laboratories to detect honey adulteration and will serve as a powerful preventive measure against fraudulent practices in the global honey market. Full article
(This article belongs to the Special Issue Chromatography/Mass Spectrometry for the Determination of Food Authenticity and Food Analysis)
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14 pages, 2617 KiB  
Article
Headspace Determination of Acetone and Aromatic Hydrocarbons in Soil Using a Homebuilt, Inexpensive Gas Chromatograph with Photoionization Detection
by Cameron Shane, Carly M. Kennell, Michael J. Geyer, Thomas N. Loegel and Neil D. Danielson
Separations 2025, 12(2), 46; https://doi.org/10.3390/separations12020046 - 12 Feb 2025
Viewed by 783
Abstract
We have designed, built, and characterized an inexpensive gas chromatograph with photoionization detection using readily commercially available components. These include a home carbonation CO2 cylinder for the carrier gas, headspace sampling using a low pressure six port valve, a standard 30 m [...] Read more.
We have designed, built, and characterized an inexpensive gas chromatograph with photoionization detection using readily commercially available components. These include a home carbonation CO2 cylinder for the carrier gas, headspace sampling using a low pressure six port valve, a standard 30 m wide-bore capillary column, a consumer convection oven including added insulation with a thermocouple, and a photoionization sensor enclosed in a flow cell. The chromatography retention time reproducibility is good due to temperature control within 0.5 °C. The headspace linearity response using a 0.5 mL injection of benzene was from 10 to 250 ppm, with the limit of detection estimated at 4 ppm. The application of this instrument to the headspace monitoring of four soil samples spiked with a commercial adhesive cleaner containing acetone, ethyl benzene, and xylenes was possible. The interaction of acetone with the two different potting soil samples, likely due to their high organic content, was persistent for at least 30 min, even above an ambient temperature (60 °C). A comparison of linear plots of the signal versus volatilization time over the first 20 min showed substantially larger slopes for the two yard soil samples, indicating the rapid volatilization of acetone from these lower organic content soils, as compared to the two potting soil samples. This GC-PID instrument can be considered portable because it can be easily taken apart, transported, and reassembled. One viable option for the extension of the applications of this instrument is to provide hands-on teaching of GC. Full article
(This article belongs to the Section Chromatographic Separations)
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15 pages, 6707 KiB  
Article
Chiral Separation and Determination of Enantiomer Elution Order of Novel Ketamine Derivatives Using CE-UV and HPLC-UV-ORD
by Elisabeth Seibert, Eva-Maria Hubner and Martin G. Schmid
Separations 2025, 12(2), 44; https://doi.org/10.3390/separations12020044 - 11 Feb 2025
Viewed by 1180
Abstract
Besides the well-known hallucinogenic ketamine, various novel ketamine derivatives are available on the illicit drug market, sold as designer drugs. Minor chemical changes to the parent compound aim to circumvent existing narcotic drug laws while mimicking the effects of the original substance. Ketamine [...] Read more.
Besides the well-known hallucinogenic ketamine, various novel ketamine derivatives are available on the illicit drug market, sold as designer drugs. Minor chemical changes to the parent compound aim to circumvent existing narcotic drug laws while mimicking the effects of the original substance. Ketamine and some of its derivatives possess a chiral centre and therefore exist as two enantiomers. While differences in the effects of S- and R-ketamine are well studied, this is not the case for ketamine derivatives. Therefore, the development and adaptation of suitable enantioseparation methods for those compounds is important to face the problems of the constantly changing drug market. In this study, different chiral separation methods for capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) were tested on 11 ketamine derivatives. Some of them were enantioseparated for the first time due to their novelty. All compounds were at least partially separated on both instruments. HPLC separations were conducted using four different polysaccharide-based chiral stationary phases. Furthermore, an optical rotation detector coupled to the HPLC enabled the determination of the enantiomer elution order. In CE analysis, enantioseparation was achieved using 2% (w/v) acetyl-β-cyclodextrin or carboxymethyl- β-cyclodextrin in 10 mM di-sodium hydrogen phosphate as the background electrolyte in capillary electrophoresis. Full article
(This article belongs to the Section Chromatographic Separations)
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20 pages, 3734 KiB  
Article
Strengthened Effect of Surface-Active Ionic Liquids on Curcumin Solubility and Extraction Performance of Curcuminoids
by Dan Li, Yuxin Qin, Jingxing Li, Subhan Mahmood, Jianqin Shi, Yu Cao and Shun Yao
Separations 2025, 12(2), 29; https://doi.org/10.3390/separations12020029 - 26 Jan 2025
Viewed by 652
Abstract
As a kind of bioactive component in the rhizome of natural plant Curcuma longa L. (turmeric), curcumin is almost insoluble in water at neutral and acidic pH, which limits its further utilization and development. At the same time, traditional extraction and separation processes [...] Read more.
As a kind of bioactive component in the rhizome of natural plant Curcuma longa L. (turmeric), curcumin is almost insoluble in water at neutral and acidic pH, which limits its further utilization and development. At the same time, traditional extraction and separation processes typically require the use of a large number of organic solvents. Ionic liquids (ILs) are organic molten salts with melting points below 100 °C. When an ionic liquid exists in a liquid state at or near room temperature, it is referred to as a room-temperature ionic liquid (RTIL). They have a temperature range, good physical and chemical stability, and good structural designability. They have a strong solubilization enhancement effect for many organic compounds. This study first explored the molecular forms of curcumin in ionic liquid aqueous solutions and the intermolecular interactions between curcumin and ionic liquids using spectral analysis and computational chemistry methods; furthermore, using an ionic liquid aqueous solution as an extraction agent, curcumin-like substances (curcuminoids) were extracted from turmeric powders under ultrasound assisted conditions, revealing the relationship between the structure of the ionic liquid and the extraction efficiency. After that, a kinetic study was conducted for the extraction of curcuminoids from turmeric powders, using second-order kinetics fitting to obtain the rate constant and initial extraction rate during the extraction process. Finally, the comparison with a ComplexGAPI tool and antioxidant experiment was performed on the extraction by using ionic liquids and traditional solvent. The full results can provide reference for the design of IL extractants and their application for natural products. Full article
(This article belongs to the Special Issue Green Separation and Purification Technology)
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13 pages, 873 KiB  
Article
HILIC-DAD Method for Simultaneous Determination of Acid and Basic Drugs: Application to the Quantitation of Ibuprofen, Atenolol, and Salbutamol in Urine After Solid-Phase Extraction
by Noelia Rosales-Conrado, Laura Pedrera-Cajas, Elvira Soliño-Rodríguez and María Eugenia León-González
Separations 2025, 12(2), 26; https://doi.org/10.3390/separations12020026 - 26 Jan 2025
Viewed by 1007
Abstract
A simple method has been developed for the simultaneous analysis of ibuprofen (acid drug), and salbutamol and atenolol (basic drugs) in urine samples at concentrations of 0.40 µg·mL−1. Simultaneous chromatographic separation has been possible using hydrophilic interaction liquid chromatography (Kinetex HILIC [...] Read more.
A simple method has been developed for the simultaneous analysis of ibuprofen (acid drug), and salbutamol and atenolol (basic drugs) in urine samples at concentrations of 0.40 µg·mL−1. Simultaneous chromatographic separation has been possible using hydrophilic interaction liquid chromatography (Kinetex HILIC® column (2.1 mm × 150 mm, 2.6 μm particle size diameter and 100 Å pore size) combined with gradient elution by employing a mixture of acetonitrile–acetate buffer 5 mM at pH 6 (from 95:5 to 75:25 (v/v)) as the mobile phase. Detection was performed at 227 and 275 nm. The simultaneous preconcentration and cleaning of the sample has been possible by solid-phase extraction using the HLB ExtraBond® polymeric-type sorbent (which is a pyrrolidone-modified divinylbenzene polystyrene type). It has provided recoveries between (63 ± 9)% for salbutamol, (74 ± 8)% for ibuprofen, and (96 ± 9)% for atenolol in 10 mL of synthetic urine containing 4.0 μg of each of the drugs analyzed. The detection limits were 0.025 µg·mL−1 for ibuprofen, µg·mL−1 for salbutamol, and 0.007 µg·mL−1 for atenolol. The detection limits obtained allow the evaluation of the free forms of ibuprofen, atenolol, and salbutamol at the excreted concentration levels at the therapeutic doses usually administered. The coefficients of variation between days were in the range 4.5–10.9%. Full article
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17 pages, 2312 KiB  
Article
Green Chemistry Method for Analyzing Bisphenol A in Milk
by Angela M. Encerrado Manriquez and Wen-Yee Lee
Separations 2025, 12(2), 25; https://doi.org/10.3390/separations12020025 - 25 Jan 2025
Viewed by 1170
Abstract
A simple, fast, green, and sensitive method for determining Bisphenol A (BPA) levels in commercial milk was developed using a solventless sample preparation technique known as stir bar sorptive extraction, coupled with thermal desorption–gas chromatography/mass spectrometry. BPA was selected due to its ubiquitous [...] Read more.
A simple, fast, green, and sensitive method for determining Bisphenol A (BPA) levels in commercial milk was developed using a solventless sample preparation technique known as stir bar sorptive extraction, coupled with thermal desorption–gas chromatography/mass spectrometry. BPA was selected due to its ubiquitous presence in the environment and its classification as an endocrine-disrupting chemical of concern (i.e., its ability to mimic hormone functions). Studies have reported that BPA can leach into various food sources, including milk, a dietary staple for infants. It is critical to have an effective and efficient process for monitoring the presence of BPA in milk to protect children’s health. Current detection methods for BPA in milk are lengthy and tedious and tend to require the use of organic solvents for the extraction of BPA. This optimized “green” method provides an effective alternative for BPA detection in a challenging matrix, e.g., milk. Factors such as pH (1.5, 6, and 13), temperature (70–80 °C), and sonication (1 h, 2 h, and 3 h) were studied with a BPA-spiked whole milk sample (final concentration of 8 ppb) to optimize the extraction efficiency without the use of solvents. The developed methodology improves BPA recovery from whole milk by over 50%, with a detection limit in the parts per trillion range (45 ng/L). The sample preparation developed in this report rendered a more sensitive option for analyzing BPA in milk, with a limit of detection in the parts per trillion range (compared to low ppb) even though the recovery performance is not as good as in reported studies (54% vs. >85%); nonetheless, it provides a green alternative for future studies assessing BPA exposure through dairy products. Full article
(This article belongs to the Special Issue Chromatographic Methods for Environment, Biota and Food Contaminants Analysis)
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21 pages, 531 KiB  
Review
Plant Sample Preparation for Metabolomics, Lipidomics, Ionomics, Fluxomics, and Peptidomics
by Walace Breno da Silva, Gabriel Felipe Hispagnol, Emanuel Victor dos Santos Nunes, Ian Castro-Gamboa and Alan Cesar Pilon
Separations 2025, 12(2), 21; https://doi.org/10.3390/separations12020021 - 24 Jan 2025
Viewed by 1723
Abstract
Plant metabolomics, lipidomics, ionomics, fluxomics, and peptidomics are essential approaches for exploring how plants respond to epigenetic, pathological, and environmental stimuli through comprehensive chemical profiling. Over the past decades, significant progress has been made in protocols and methodologies to address the challenges in [...] Read more.
Plant metabolomics, lipidomics, ionomics, fluxomics, and peptidomics are essential approaches for exploring how plants respond to epigenetic, pathological, and environmental stimuli through comprehensive chemical profiling. Over the past decades, significant progress has been made in protocols and methodologies to address the challenges in sample collection and extraction. Despite these advancements, sample preparation remains intricate, with ongoing debates about the most effective strategies. This review emphasizes the importance of clear research questions and well-designed experiments to minimize complexity, save time, and enhance reproducibility. It provides an overview of the key steps in these fields, including harvesting, drying, extraction, and data pre-acquisition for major analytical platforms. By discussing best practices and common challenges, this review aims to streamline methods and promote more consistent and reliable research outcomes. Full article
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14 pages, 1399 KiB  
Article
Development of a Validated HPLC-UV Method for the Determination of Panthenol, Hesperidin, Rutin, and Allantoin in Pharmaceutical Gel-Permeability Study
by Sofia Almpani, Pavlina-Ioanna Agiannitou, Paraskevi Kyriaki Monou, Georgios Kamaris and Catherine K. Markopoulou
Separations 2025, 12(2), 19; https://doi.org/10.3390/separations12020019 - 22 Jan 2025
Cited by 1 | Viewed by 1415
Abstract
A pressure ulcer is the necrosis of the skin and tissues due to prolonged pressure. Its prevention and treatment are of great importance not only for the health but also for the patient’s quality of life and are considered the highest priority. In [...] Read more.
A pressure ulcer is the necrosis of the skin and tissues due to prolonged pressure. Its prevention and treatment are of great importance not only for the health but also for the patient’s quality of life and are considered the highest priority. In the present study, a reliable analytical method is developed for the quantitative determination of panthenol, hesperidin, rutin, and allantoin by HPLC and UV detectors. The substances were formulated into a pharmaceutical gel, with healing and regenerative properties recommended for first- and second-degree bedsores. Their separation was achieved with a ZIC-Hilic column (150 × 4.6 mm), 5 μm, and a gradient elution system (Solvent A: CH3CN-H2O, 90:10 v/v/v and Solvent B: CH3CN-H2O, 10:90 v/v). The method was evaluated based on the required specifications (%RSD < 2, % Recovery > 96.7%) and was applied for the quantitative extraction of the active substances in the gel. The purification of the samples was carried out using experimental design and Cross-D-Optimal methodology (%RSD < 2.2, % Recovery > 96.9%). Subsequently, the gel was studied in terms of the transdermal permeation of the active pharmaceutical ingredients (APIs) through vertical Franz cells and their behavior (Papp values) was compared with a similar aqueous suspension product (reference formulation). The samples were reconstituted by lyophilization and extraction with methanol. According to the results, the drugs exhibit satisfactory penetration, ensuring the healing of problems that may occur in the skin and dermis. Full article
(This article belongs to the Collection State of the Art in Separation Science)
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15 pages, 732 KiB  
Article
Assessment of Green Extraction Techniques in the Utilization of Oak Tree (Quercus robur) and Mugwort (Artemisia vulgaris) Biomass for the Production of Bioactive Extracts
by David Villanueva-Bermejo, Diego Martín Hernández, Elvis Judith Hernández, Susana Santoyo and Tiziana Fornari
Separations 2025, 12(1), 17; https://doi.org/10.3390/separations12010017 - 18 Jan 2025
Viewed by 875
Abstract
The aim of this study was to investigate the suitability of Pressurized Liquid Extraction (PLE) and Supercritical Fluid Extraction (SFE) for Quercus robur bark and Artemisia vulgaris extraction. PLE of Q. robur and A. vulgaris were carried out at different temperatures with water, [...] Read more.
The aim of this study was to investigate the suitability of Pressurized Liquid Extraction (PLE) and Supercritical Fluid Extraction (SFE) for Quercus robur bark and Artemisia vulgaris extraction. PLE of Q. robur and A. vulgaris were carried out at different temperatures with water, ethanol and several hydroalcoholic mixtures. SFE of A. vulgaris was performed at different pressures and ethanol concentrations. The anti-inflammatory activity of Q. robur extracts, the antibacterial activity of A. vulgaris extracts and the antioxidant activity of the extracts from both materials were determined. The highest phenolic compound content and antioxidant activity of Q. robur extracts were achieved with water at 100 °C (487.97 mg GAE/g and 3741 µg trolox/g). The highest values for A. vulgaris extracts were obtained with ethanol at 200 °C (149.16 mg/g and 437.13 µmol/g). The ethanolic extract at 150 °C from A. vulgaris had a noticeable anti-inflammatory activity (inhibition of TNF-α and IL-6 secretion near basal values and inhibition of IL-1β higher than 80% at 20 µg/mL). A. vulgaris extracts obtained by SFE exerted antibacterial activity against E. coli (IC50 of 1388 µg/mL with neat SCCO2 at 15 MPa) and S. aureus (1406 µg/mL using SCCO2 with 10% ethanol). Full article
(This article belongs to the Special Issue Research Progress for Isolation of Plant Active Compounds)
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22 pages, 3209 KiB  
Review
Microextraction-Based Techniques for the Determination of Beta-Blockers in Biological Fluids: A Review
by Styliani Nisyriou and Constantinos K. Zacharis
Separations 2025, 12(1), 14; https://doi.org/10.3390/separations12010014 - 12 Jan 2025
Cited by 2 | Viewed by 1119
Abstract
Sample preparation is a critical step in the analytical process. Apart from the traditional sample cleanup approaches, microextraction-based techniques have attracted much attention in recent years and especially from researchers working in the analysis of beta-blockers. Developing sensitive and selective analytical methods is [...] Read more.
Sample preparation is a critical step in the analytical process. Apart from the traditional sample cleanup approaches, microextraction-based techniques have attracted much attention in recent years and especially from researchers working in the analysis of beta-blockers. Developing sensitive and selective analytical methods is essential for detecting these compounds in complex matrices. The present review aims to provide an overview of microextraction-based analytical techniques for the determination of beta-blockers in biological samples, covering a time frame of the last decade. Detailed information on materials/coatings and instrumental configurations are provided. Full article
(This article belongs to the Section Bioanalysis/Clinical Analysis)
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30 pages, 2179 KiB  
Review
Advancements in Microextraction by Packed Sorbent: Insights into Sorbent Phases and Automation Strategies
by Rafael Oliveira Martins, João Victor Basolli Borsatto, Camila Will and Fernando Mauro Lanças
Separations 2025, 12(1), 11; https://doi.org/10.3390/separations12010011 - 8 Jan 2025
Viewed by 1230
Abstract
Miniaturized solid-based approaches have added an eco-friendly dimension to analytical procedures, establishing themselves as promising strategies for a wide range of applications. Among these, microextraction by packed sorbent (MEPS) stands out due to its ability to facilitate efficient sample interaction with a densely [...] Read more.
Miniaturized solid-based approaches have added an eco-friendly dimension to analytical procedures, establishing themselves as promising strategies for a wide range of applications. Among these, microextraction by packed sorbent (MEPS) stands out due to its ability to facilitate efficient sample interaction with a densely packed sorb ent phase within the microextraction system. MEPS offers several advantages, including preconcentration capabilities and the use of minimal sample and solvent volumes, making it an appealing choice for modern analytical workflows. Since the extraction efficiency is largely dictated by the sorbent phase, recent advancements in sorbent design have garnered considerable attention in the field of sample preparation. Innovations in sorbent phases have not only enhanced the MEPS efficiency but also enabled the development of semi- and fully automated systems, paving the way for high-throughput methodologies. These advancements have elevated MEPS beyond traditional offline miniaturized sample preparation methods, offering new opportunities for streamlined and scalable analyses. Therefore, this study provides a comprehensive overview of novel sorbent phases used in MEPS, with a particular focus on both bio-based and synthetic materials. Furthermore, it explores the semi- and fully automated aspects of MEPS, highlighting current trends, technological advancements, and future directions in this rapidly evolving field. Full article
(This article belongs to the Special Issue Separation Techniques on a Miniaturized Scale)
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17 pages, 2691 KiB  
Article
Phytochemical Profile Screening and Selected Bioactivity of Myrtus communis Berries Extracts Obtained from Ultrasound-Assisted and Supercritical Fluid Extraction
by Ilir Mërtiri, Gigi Coman, Mihaela Cotârlet, Mihaela Turturică, Nicoleta Balan, Gabriela Râpeanu, Nicoleta Stănciuc and Liliana Mihalcea
Separations 2025, 12(1), 8; https://doi.org/10.3390/separations12010008 - 3 Jan 2025
Cited by 1 | Viewed by 1128
Abstract
This research paper investigates the phytochemical profile, antioxidant activity, antidiabetic potential, and antibacterial activity of Myrtus communis berries. Two extraction methods were employed to obtain the extracts: solid–liquid ultrasound-assisted extraction (UAE) and supercritical fluid extraction (SFE). The extracts were characterized using spectrophotometric methods [...] Read more.
This research paper investigates the phytochemical profile, antioxidant activity, antidiabetic potential, and antibacterial activity of Myrtus communis berries. Two extraction methods were employed to obtain the extracts: solid–liquid ultrasound-assisted extraction (UAE) and supercritical fluid extraction (SFE). The extracts were characterized using spectrophotometric methods and Reversed-Phase High-Performance Liquid Chromatography (RP-HPLC). The UAE extract exhibited higher total flavonoid and anthocyanin content, while the SFE extract prevailed in total phenolic content and antioxidant activity in the DPPH radical screening assay. RP-HPLC characterization identified and quantified several polyphenolic compounds. In the UAE extract, epigallocatechin was found in a concentration of 2656.24 ± 28.15 µg/g dry weight (DW). In the SFE extract, cafestol was the identified compound with the highest content at a level of 29.65 ± 0.03 µg/g DW. Both extracts contained several anthocyanin compounds, including cyanidin 3-O-glucoside chloride, cyanidin-3-O-rutinoside chloride, malvidin-3-O-glucoside chloride, pelargonidin 3-O-glucoside chloride, peonidin 3-O-glucoside chloride, and peonidin-3-O-rutinoside chloride. The antidiabetic potential was evaluated in vitro by measuring the inhibition of α-amylase from porcine pancreas (type I-A). The results highlighted the ability of myrtle berry extracts to inhibit α-amylase enzymatic activity, suggesting its potential as an alternative for controlling postprandial hyperglycemia. The UAE extract showed the lowest IC50 value among the two extracts, with an average of 8.37 ± 0.52 µg/mL DW. The antibacterial activity of the extracts was assessed in vitro against Bacillus spp., Escherichia coli, and Staphylococcus aureus using the disk diffusion method. Both myrtle berry extracts exhibited similar antibacterial activity against the tested bacterial strains. The results support further investigation of myrtle berries extracts as a potential ingredient in functional food formulation, particularly due to its antioxidant, antidiabetic, and antibacterial properties. Full article
(This article belongs to the Special Issue Green Extraction Techniques of Bioactive Compounds from Natural Sources)
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16 pages, 2546 KiB  
Article
Volatile Organic Compounds in Honey: Tandem Mass Spectrometry as Tool to Quantitate Priority VOCs
by Evangelia N. Tzanetou, Efstathia Vousaxaki, Kyriaki Machera, Jozef van der Steen and Konstantinos M. Kasiotis
Separations 2024, 11(12), 352; https://doi.org/10.3390/separations11120352 - 17 Dec 2024
Viewed by 1270
Abstract
A headspace gas chromatographic tandem mass spectrometric (HS-GC-MS/MS) method was developed and fully validated, aiming for the simultaneous determination of 25 volatile organic compounds (VOCs, some of them previously unreported in honey bee studies) in 52 selected honey samples from Greece. The HS [...] Read more.
A headspace gas chromatographic tandem mass spectrometric (HS-GC-MS/MS) method was developed and fully validated, aiming for the simultaneous determination of 25 volatile organic compounds (VOCs, some of them previously unreported in honey bee studies) in 52 selected honey samples from Greece. The HS conditions were optimized, and method validation criteria were extensively investigated. The existence impact of the matrix effect was assessed, and matrix-matched calibration curves were developed for quantification purposes. The limits of quantification of the 25 analytes ranged from 0.2 ng g−1 to 0.6 ng g−1. Isoprene was the most commonly detected VOC, followed by octane and styrene. Other detected VOCs include benzene, n-hexane, trimethylbenzenes, xylenes, toluene, and p-dichlorobenzene. Concentrations fluctuated from 0.5 ng g−1 for isoprene and toluene, as well as 1,2,4-trimethylbenzene, to 22.6 ng g−1 for isoprene. Despite VOCs not being at the forefront of honey’s potential contamination, their prevalence in honey can provide significant data for human health risk assessment, considering their undisputable widespread consumption and the documented potential toxicity of VOCs in humans. In this sense, risk assessment for adults and children, as depicted in the hazard quotient and index and carcinogenic risk determination, did not disclose any potential threat after consumption of the investigated honey samples. Full article
(This article belongs to the Special Issue Chemical and Contaminant Residue Analysis via Chromatography)
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13 pages, 1187 KiB  
Article
Body Volatilome Study Strategy for COVID-19 Biomarker Identification Considering Exogenous Parameters
by Elsa Boudard, Nabil Moumane, José Dugay, Jérôme Vial and Didier Thiébaut
Separations 2024, 11(12), 336; https://doi.org/10.3390/separations11120336 - 22 Nov 2024
Cited by 1 | Viewed by 1111
Abstract
Since the 1950s, the screening of the body volatilome has proven to be a powerful tool for preventing diseases from spreading. Following the COVID-19 crisis, several studies began investigating the connection between viruses and the body volatilome, gradually identifying potential biomarkers, which varied [...] Read more.
Since the 1950s, the screening of the body volatilome has proven to be a powerful tool for preventing diseases from spreading. Following the COVID-19 crisis, several studies began investigating the connection between viruses and the body volatilome, gradually identifying potential biomarkers, which varied depending on the study. To try to elucidate potential sources of inconsistency in biomarker findings, we decided to set up a study taking into consideration the factors often overlooked in previous studies. The VOCs constituting the body volatilomes of 40 COVID-19 patients and 13 healthy subjects were sampled by using PowerSorb® as the sorbent phase. Thermodesorption, followed by comprehensive two-dimensional gas chromatography combined with time-of-flight mass spectrometry (TD-GC×GC/TOF MS), was utilized for the analysis. A non-targeted biomarker research methodology compared Covid(+) and Covid(−) chromatograms, assessing statistical significance and peak area changes. Out of the 25 compounds highlighted, 13 associated with cosmetic products were excluded, and 8 linked to air pollution in urban settings were also excluded. Finally, after having quantitatively evaluated the potential sources of the compounds (cosmetic or environmental), 4 compounds remained and their relevance was assessed using ROC curves. Among them, hexanoic acid, 2-ethyl- identification was confirmed with standard and led to an area-under-the-curve value of 92%. More in-depth studies are needed to investigate the specificity of the biomarker in relation to COVID-19, but the strategy of this study shows how to avoid obtaining data that are biased by exogenous factors. Full article
(This article belongs to the Section Bioanalysis/Clinical Analysis)
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17 pages, 3919 KiB  
Article
Fatty Acid Profiling in Greek Wines by Liquid Chromatography–High-Resolution Mass Spectrometry (LC-HRMS)
by Maroula G. Kokotou
Separations 2024, 11(11), 321; https://doi.org/10.3390/separations11110321 - 6 Nov 2024
Cited by 2 | Viewed by 1097
Abstract
In recent years, the interest in lipids present in wines has increased, because these natural components, even at low or very low concentrations, play an important role in wine evolution and quality and contribute substantially to the taste and mouthfeel of wines. Herein, [...] Read more.
In recent years, the interest in lipids present in wines has increased, because these natural components, even at low or very low concentrations, play an important role in wine evolution and quality and contribute substantially to the taste and mouthfeel of wines. Herein, we present a liquid chromatography–high-resolution mass spectrometry (LC-HRMS) method for the profiling of free fatty acids (FFAs) in wines. The method is fast and allows the simultaneous determination of twenty-seven saturated and unsaturated FFAs in wine samples, avoiding any prior derivatization step. After validation, a variety of white and rose commercial wine samples from the Greek market, either sparkling or non-sparkling, were analyzed by the present method. The majority of wine FFAs are saturated long aliphatic, in particular palmitic (C16:0) and stearic (C18:0) acids, followed by myristic (C14:0) and pentadecanoic (C15:0) acids, while oleic (C18:1), palmitoleic (C16:1) and linoleic (C18:2) acids were quantified among the unsaturated FAs. The medium-chain C6:0 and the unsaturated C16:1 and C18:2 acids were found at higher concentrations in rose wines compared to white. Full article
(This article belongs to the Special Issue Isolation and Identification of Biologically Active Natural Compounds)
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17 pages, 5104 KiB  
Article
QuEChERS-Based Method for the Determination of Fipronil in Protein Baits and Vespa velutina Larvae by HPLC-DAD and GC-MS
by Omaira de la Hera, Aritza Izaguirre, Arrate Rivas and Rosa María Alonso
Separations 2024, 11(11), 317; https://doi.org/10.3390/separations11110317 - 3 Nov 2024
Viewed by 1685
Abstract
Protein baits containing fipronil as a biocide have shown their effectivity as a control method for Vespa velutina nigrithorax (Lepeletier, 1836) in apiaries. This biocide is not selective for Vespa velutina, so it is important to use the minimum dose to inactivate [...] Read more.
Protein baits containing fipronil as a biocide have shown their effectivity as a control method for Vespa velutina nigrithorax (Lepeletier, 1836) in apiaries. This biocide is not selective for Vespa velutina, so it is important to use the minimum dose to inactivate a nest. Therefore, the aim of this work was the development of analytical methods for the determination of fipronil in protein baits for quality control purposes and in larvae of Vespa velutina to determine the biocide content after protein bait ingestion and to acquire knowledge on fipronil metabolism in larvae. For this purpose, a Quechers-based HPLC-PDA method was developed and validated for the determination of fipronil in both matrixes. Furthermore, a GC-MS method was developed for the analysis of fipronil and its metabolites in dead Vespa velutina larvae fed with a mash containing 0.01% fipronil. Quechers-based HPLC-DAD allowed for the determination of the fipronil content in baits. Fipronil and the metabolites fipronil sulfone and fipronil sulfide were identified by GC-MS in extracts of larvae fed with a protein mash containing 0.01% fipronil. The transformation of fipronil into fipronil sulfone inside the larvae and the high toxicity of this metabolite open the possibility to produce protein baits with lower biocide concentrations. Full article
(This article belongs to the Section Chromatographic Separations)
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13 pages, 4888 KiB  
Article
A Revisit to Effervescence-Assisted Microextraction of Non-Polar Organic Compounds Using Hydrophobic Magnetic Nanoparticles—Application to the Determination of UV Filters in Natural Waters
by Efthymia Toti, Vasiliki Gouma, Vasiliki I. Karagianni and Dimosthenis L. Giokas
Separations 2024, 11(11), 315; https://doi.org/10.3390/separations11110315 - 1 Nov 2024
Viewed by 1402
Abstract
In this work, we revisited the method of effervescence-assisted microextraction, aiming to assess the effects of the process of effervescence on the extraction efficiency of organic compounds. We used a magnetic nano-sorbent material composed of stearic acid-coated cobalt-ferrite magnetic nanoparticles as an adsorbent [...] Read more.
In this work, we revisited the method of effervescence-assisted microextraction, aiming to assess the effects of the process of effervescence on the extraction efficiency of organic compounds. We used a magnetic nano-sorbent material composed of stearic acid-coated cobalt-ferrite magnetic nanoparticles as an adsorbent and dispersed it in water using 12 combinations of acid and base mixtures at two different mass ratios. The solution pH, the ionic strength, and the duration of effervescence were calculated and correlated to the extraction efficiency of nonpolar UV filters from aqueous samples as model organic compounds. Our findings provide a general perspective into the influence of the process of effervescence on extraction efficiency. Based on these findings, we developed and optimized a new analytical method for extracting UV filters from water samples using HPLC-UV as a detector. Under the optimum experimental conditions (0.2 g fumaric acid/0.1 g Na2CO3, 50 mg of magnetic nanoparticles and methanol as an elution solvent assisted by vortex agitation for 5 min) the method was found to afford good linearity in the calibration curves expanding by two orders of magnitude, satisfactory reproducibility and repeatability (1.8–11.1%), and high recoveries (78.4–127.1%). This research provides a new perspective on the influence of the process of effervescence on the extraction efficiency of nonpolar organic compounds and introduces a new method for extracting UV filters from aqueous media. Full article
(This article belongs to the Section Environmental Separations)
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18 pages, 5440 KiB  
Article
Eco-Friendly Green Approach to the Biosorption of Hazardous Dyes from Aqueous Solution on Ragweed (Ambrosia artemisiifolia) Biomass
by Natalija Nedić, Tamara Tadić, Bojana Marković, Aleksandra Nastasović, Aleksandar Popović and Sandra Bulatović
Separations 2024, 11(11), 310; https://doi.org/10.3390/separations11110310 - 28 Oct 2024
Viewed by 1120
Abstract
The presented research includes the preparation, characterization, and implementation of magnetic biosorbent (Fe3O4/RWB), obtained from ragweed (Ambrosia artemisiifolia) biomass. Fe3O4/RWB was examined for the removal of a hazardous dye, malachite green (MG), from [...] Read more.
The presented research includes the preparation, characterization, and implementation of magnetic biosorbent (Fe3O4/RWB), obtained from ragweed (Ambrosia artemisiifolia) biomass. Fe3O4/RWB was examined for the removal of a hazardous dye, malachite green (MG), from an aqueous solution in a batch system. The effects of the experimental parameters—initial dye concentration (10–300 mg/L), contact time (0–120 min), biosorbent dose (1–5 g/L), initial pH (2–10), ionic strength (0–1 mol/L), and temperature (298–318 K) on dye biosorption—were studied. The results showed that increases in biosorbent dose, contact time, and initial pH led to an increase in biosorption efficiency, while the increase in initial dye concentration, the ionic strength, and temperature had the opposite effect. The biosorption kinetics for MG on Fe3O4/RWB were analyzed with pseudo-first-order, pseudo-second-order, and Elovich kinetic models, while the Langmuir, Freundlich and Temkin isotherm models were used for equilibrium data analysis. It was observed that the MG biosorption followed the pseudo-second-order kinetic model, whereas the Langmuir model was the best fit for the equilibrium biosorption data of MG, with a Qmax of 34.1 mg/g. the desorption of MG from Fe3O4/RWB indicated reusability in five adsorption/desorption cycles, good performance, and potential in practical applications. Full article
(This article belongs to the Special Issue Materials from Biomass and Waste for Adsorption Applications)
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12 pages, 1622 KiB  
Article
Investigation of Metoprolol Concentrations in Plasma Using Automated Sample Preparation and LC-MS/MS Detection
by Ionel-Bogdan Cioroiu, Mona-Elisabeta Dobrin, Marius Niculaua, Constantin-Bogdan Nechita and Valeriu V. Cotea
Separations 2024, 11(11), 306; https://doi.org/10.3390/separations11110306 - 24 Oct 2024
Viewed by 1347
Abstract
Metoprolol (MTP), a selective beta-1 adrenergic blocker, is commonly administered in the form of succinate or tartrate salts, depending on the pharmaceutical formulation. It is typically prescribed in oral forms as either immediate-release or extended-release tablets. This study describes a chromatographic method using [...] Read more.
Metoprolol (MTP), a selective beta-1 adrenergic blocker, is commonly administered in the form of succinate or tartrate salts, depending on the pharmaceutical formulation. It is typically prescribed in oral forms as either immediate-release or extended-release tablets. This study describes a chromatographic method using automated sample clean-up and elution via a reversed-phase mechanism. A TurboFlow approach was applied with a Cyclone P column, and the elution was performed isocratically using a mobile phase of water and acetonitrile (0.1% v/v formic acid) within 4.5 min. Quantification of MTP was achieved using triple quadrupole mass spectrometry, with the transition m/z 268.1 → m/z 130.96 for metoprolol, while bisoprolol fumarate, the internal standard, was detected at m/z 326.3 → m/z 116.2. The method was validated according to bioequivalence guidelines. Selectivity was assessed by checking for potential interferences from blank samples or related compounds formed during sample preparation. Precision and accuracy were evaluated both within and between runs, with a maximum coefficient of variation (CV%) of 10.28 and a maximum relative error (ER%) of 5.38. Linearity was demonstrated over the range of 5 ng/L to 1000 ng/L, with a lower limit of quantification at 0.042 ng/L, made possible by injecting larger sample volumes. A matrix effect of 89% was considered acceptable when compared to standard solutions. Plasma concentrations of MTP were monitored in patients administered either 50 mg or 100 mg doses. For the 50 mg dose, plasma levels reached up to 34 μg/L, while the 100 mg dose produced concentrations ranging from 3.56 to 50.81 μg/L. Although the higher dose generally resulted in elevated plasma levels, significant variability was observed. A strong correlation (r = 0.992) was found between the administered dose and plasma concentration, though variations in absorption rates and patient demographics likely contributed to the observed variability. This method provides a reliable analytical approach suitable for pharmacokinetic and clinical studies involving metoprolol. Full article
(This article belongs to the Special Issue Separation Techniques in Drug Analysis)
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18 pages, 3713 KiB  
Article
Retention Mechanisms of Basic Compounds in Liquid Chromatography with Sodium Dodecyl Sulfate and 1-Hexyl-3-Methylimidazolium Chloride as Mobile Phase Reagents in Two C18 Columns
by Carlos Josué Tereba-Mamani, Maria Celia Garcia-Alvarez-Coque and María José Ruiz-Ángel
Separations 2024, 11(10), 300; https://doi.org/10.3390/separations11100300 - 19 Oct 2024
Viewed by 1243
Abstract
Reversed-phase liquid chromatography (RPLC) relies on a non-polar stationary phase and a more polar hydro-organic mobile phase, where compound retention is primarily governed by hydrophobicity, with more hydrophobic compounds being retained longer. The introduction of secondary equilibria in the chromatographic system through additives, [...] Read more.
Reversed-phase liquid chromatography (RPLC) relies on a non-polar stationary phase and a more polar hydro-organic mobile phase, where compound retention is primarily governed by hydrophobicity, with more hydrophobic compounds being retained longer. The introduction of secondary equilibria in the chromatographic system through additives, such as anionic surfactants and ionic liquids (ILs), was proposed to mitigate ionic interactions between positively charged analytes and the anionic free silanol groups in non-endcapped stationary phases, thereby preventing increased retention and peak tailing. Additionally, the combined hydrophobic and ionic interactions between cationic analytes and the ions in these additives was demonstrated to create mixed retention mechanisms that influence retention and selectivity. In this regard, this study investigates aqueous chromatographic systems incorporating both the anionic surfactant sodium dodecyl sulfate (SDS) and the IL 1-hexyl-3-methylimidazolium chloride as mobile phase reagents. This combination of reagents modulates the retention, eliminating the need for organic solvents and resulting in highly sustainable HPLC procedures. The chromatographic behavior was assessed using two different C18 columns (Zorbax Eclipse and XTerra-MS). The strength of solute interactions was estimated by calculating equilibrium parameters and the contributions of hydrophobic and ionic interactions through simple mathematical models. Focusing on the retention of six basic drugs (β-adrenoceptor antagonists), the study highlighted the significant role of ionic interactions. The results demonstrate the feasibility of using aqueous systems combining SDS and an IL for the efficient separation of moderately polar basic compounds without the use of organic solvents. Full article
(This article belongs to the Section Chromatographic Separations)
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17 pages, 2804 KiB  
Article
Quantitation of Copper Tripeptide in Cosmetics via Fabric Phase Sorptive Extraction Combined with Zwitterionic Hydrophilic Interaction Liquid Chromatography and UV/Vis Detection
by Pantelitsa Pingou, Anthi Parla, Abuzar Kabir, Kenneth G. Furton, Victoria Samanidou, Spyridon Papageorgiou, Efthimios Tsirivas, Athanasia Varvaresou and Irene Panderi
Separations 2024, 11(10), 293; https://doi.org/10.3390/separations11100293 - 12 Oct 2024
Cited by 1 | Viewed by 2560
Abstract
The increasing demand for effective cosmetics has driven the development of innovative analytical techniques to ensure product quality. This work presents the development and validation of a zwitterionic hydrophilic interaction liquid chromatography method, coupled with ultraviolet detection, for the quantification of copper tripeptide [...] Read more.
The increasing demand for effective cosmetics has driven the development of innovative analytical techniques to ensure product quality. This work presents the development and validation of a zwitterionic hydrophilic interaction liquid chromatography method, coupled with ultraviolet detection, for the quantification of copper tripeptide in cosmetics. A novel protocol for sample preparation was developed using fabric phase sorptive extraction to extract the targeted analyte from the complex cosmetic cream matrix, followed by chromatographic separation on a ZIC®-pHILIC analytical column. A thorough investigation of the chromatographic behavior of the copper tripeptide on the HILIC column was performed during method development. The mobile phase consisted of 133 mM ammonium formate (pH 9, adjusted with ammonium hydroxide) and acetonitrile at a 40:60 (v/v) ratio, with a flow rate of 0.2 mL/min. A design of experiments (DOE) approach allowed precise adjustments to various factors influencing the extraction process, leading to the optimization of the fabric phase sorptive extraction protocol for copper tripeptide analysis. The method demonstrated excellent linearity over a concentration range of 0.002 to 0.005% w/w for copper tripeptide, with a correlation coefficient exceeding 0.998. The limits of detection and quantitation were 5.3 × 10−4% w/w and 2.0 × 10−3% w/w, respectively. The selectivity of the method was verified through successful separation of copper tripeptide from other cream components within 10 min, establishing its suitability for high-throughput quality control of cosmetic formulations. Full article
(This article belongs to the Special Issue Analysis and Bioanalysis of Pharmaceuticals: Sample Preparation and Chromatography)
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13 pages, 2048 KiB  
Article
Separation and Characterization of Wenjin Tongluo San Essential Oil with a Comprehensive Chromatographic Separation
by Chaoyue Wang, Xionggao Han, Guanglei Zuo and Jinghui Feng
Separations 2024, 11(10), 292; https://doi.org/10.3390/separations11100292 - 11 Oct 2024
Viewed by 1159
Abstract
The essential oil components of traditional Chinese medicine in-hospital preparation were complex, and one-dimensional chromatographic separation was difficult to completely separate them due to the limited peak capacity. This study was carried out to establish a comprehensive two-dimensional chromatographic separation and analysis method [...] Read more.
The essential oil components of traditional Chinese medicine in-hospital preparation were complex, and one-dimensional chromatographic separation was difficult to completely separate them due to the limited peak capacity. This study was carried out to establish a comprehensive two-dimensional chromatographic separation and analysis method based on countercurrent chromatography (CCC) and gas chromatography (GC). In this paper, we focused on the separation of the essential oil of the traditional Chinese medicine in-hospital preparation Wenjing Tongluo San by CCC × GC, and explored the orthogonality between the two chromatographic techniques to provide the new technical support for the screening of the active ingredients. A solvent system composed of n-hexane-ethyl acetate-methanol-water (9.5:0.5:8.5:1.5, v/v) was chosen for the first-dimensional CCC separation. All the fractions collected from CCC were transferred to GC for plotting two-dimensional contours map. The calculated capacity of the two-dimensional separation system exceeded 3000, which was 8 times more than that of the one-dimensional separation system. High orthogonality (r = 0.42) and spatial coverage factor (70.42%) were obtained. Meanwhile, all the fractions were identified by GC-MS. Our research provided a new methodology for separating essential oils in traditional Chinese medicine as well as an approach for evaluating the quality of traditional Chinese medicinal in-hospital preparation based on two-dimensional chromatographic fingerprints. Full article
(This article belongs to the Special Issue The 10th Anniversary of Separations: Advances in Separation and Analysis of Natural Products/Medicines)
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17 pages, 4999 KiB  
Article
Development and Validation of a Novel Method Using QuEChERS and UHPLC-MS-MS for the Determination of Multiple Emerging Fungicides in Surface Waters
by Pulasthi Serasinghe, Deni Taleski, Hao T. K. Nguyen, Dayanthi Nugegoda and Vincent Pettigrove
Separations 2024, 11(10), 279; https://doi.org/10.3390/separations11100279 - 24 Sep 2024
Viewed by 1573
Abstract
The increasing global reliance on pesticides for agricultural pest control has raised significant environmental concerns, particularly due to inadequate monitoring of emerging chemicals in surface waters. This study addresses the potential contamination of aquatic ecosystems by developing and validating a method for detecting [...] Read more.
The increasing global reliance on pesticides for agricultural pest control has raised significant environmental concerns, particularly due to inadequate monitoring of emerging chemicals in surface waters. This study addresses the potential contamination of aquatic ecosystems by developing and validating a method for detecting trace amounts of four recently registered fungicides: three succinate dehydrogenase inhibitors (fluopyram, penthiopyrad, pydiflumetofen) and fluopicolide, a structurally related fungicide. Employing QuEChERS-based sample extraction combined with ultra-high-performance liquid chromatography (UHPLC-MS-MS), this method achieves detection limits of 0.1 to 0.2 μg/L, with recovery rates between 90% and 110%, and intra-day relative standard deviation values well within the acceptable range of less than 20%. Applied to surface grab water samples from the greater Melbourne area, Australia, the method successfully identified all four fungicides at trace levels, including a notable high concentration of fluopyram (7.3 μg/L) during autumn, with the others intermittently detected at lower concentrations. This study represents the first documented instance of quantifiable detections of these four fungicides in Australian surface water systems. Given their high toxicity to several organisms and the limited global data on these substances, our findings underscore the critical need for continuous monitoring to inform strategies to safeguard aquatic ecosystems from these chemicals. Full article
(This article belongs to the Topic Application of Liquid Chromatography-Mass Spectrometry and Related Techniques)
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16 pages, 1893 KiB  
Article
Development of a QAMS Analysis Method for Industrial Lanolin Alcohol Based on the Concept of Analytical Quality by Design
by Kaidierya Abudureheman, Qinglin Wang, Hao Zhang and Xingchu Gong
Separations 2024, 11(9), 276; https://doi.org/10.3390/separations11090276 - 22 Sep 2024
Cited by 1 | Viewed by 1674
Abstract
The Analytical Quality by Design (AQbD) concept was adopted to establish a quantitative analysis of multi-components with a single marker (QAMS) method for industrial lanolin alcohol, targeting cholesterol, lanosterol, and 24,25-dihydrolanosterol. The potential critical method parameters (CMPs) were identified as column temperature, flow [...] Read more.
The Analytical Quality by Design (AQbD) concept was adopted to establish a quantitative analysis of multi-components with a single marker (QAMS) method for industrial lanolin alcohol, targeting cholesterol, lanosterol, and 24,25-dihydrolanosterol. The potential critical method parameters (CMPs) were identified as column temperature, flow rate, and gradient. Definitive screening design and statistical modeling were employed to optimize the gradient conditions of the mobile phase, column temperature, and flow rate. The Method Operable Design Region (MODR) was determined using a risk-based quantification approach. The robustness was assessed using a Plackett–Burman experimental design, followed by methodological validation. Optimal analytical conditions were as follows: acetonitrile (B)—water (A) mobile phase system; flow rate of 1.58 mL/min; detection wavelength of 205 nm; injection volume of 10 µL; and column temperature of 37 °C. A gradient elution program was implemented as follows: 0–19.0 min, 90.5% B; 19.0–25.0 min, 90.5–100% B; and 25.0–55.0 min, 100% B. Cholesterol served as an internal standard for quantifying lanosterol and 24,25-dihydrolanosterol, with relative correction factors of 0.4227 and 0.8228, respectively. This analytical method utilized only the cholesterol reference substance as an internal standard to quantify the content of cholesterol, lanosterol, and 24,25-dihydrolanosterol in industrial lanolin alcohol. It reduced the testing costs and enhanced efficiency, making it potentially suitable for widespread adoption in lanolin alcohol processing industries. Full article
(This article belongs to the Special Issue The 10th Anniversary of Separations: Advances in Separation and Analysis of Natural Products/Medicines)
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12 pages, 1543 KiB  
Article
Photocatalytic Degradation of Levofloxacin and Inactivation of Enterococci Levofloxacin-Resistant Bacteria Using Pure Rare-Earth Oxides
by Lorenzo Saviano, Antonietta Mancuso, Alice Cardito, Olga Sacco, Vincenzo Vaiano, Maurizio Carotenuto, Giovanni Libralato and Giusy Lofrano
Separations 2024, 11(9), 272; https://doi.org/10.3390/separations11090272 - 18 Sep 2024
Cited by 1 | Viewed by 1078
Abstract
In this study, La2O3 and CeO2 nanopowders were prepared using a simple and cost-effective precipitation method. Wide-angle X-ray diffraction (WAXD), UV-Visible reflectance diffuses (UV-Vis DRS), Raman spectroscopy, and specific surface area were used to characterize the photocatalysts, evidencing that [...] Read more.
In this study, La2O3 and CeO2 nanopowders were prepared using a simple and cost-effective precipitation method. Wide-angle X-ray diffraction (WAXD), UV-Visible reflectance diffuses (UV-Vis DRS), Raman spectroscopy, and specific surface area were used to characterize the photocatalysts, evidencing that the used preparation method was effective in the generation of crystalline CeO2 and La2O3. In particular, WAXD results showed that the average crystallite size of the achieved La2O3 and CeO2 samples were about 22 nm and 28 nm, respectively. The photocatalytic performances of the prepared catalysts were investigated in the degradation of levofloxacin (LEV) and the inactivation of a waterborne pathogen levofloxacin resistant (Enterococcus faecalis ATCC 29212) by using a photoreactor equipped with a solar simulator (SS). After 120 min, the CeO2 and La2O3 photocatalytic treatments allowed us to achieve between 75% and 83% of levofloxacin removal, respectively. A complete removal of 106 CFU/mL Enterococcus faecalis ATCC 29212 was achieved after 5 and 60 min of La2O3 and CeO2 photocatalytic processes, respectively. Full article
(This article belongs to the Special Issue Photocatalytic Materials for Pollutant Removal by Degradation)
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15 pages, 2581 KiB  
Article
Multi-Residue Analysis of Thyreostats in Animal Muscle Tissues by Hydrophilic Interaction Liquid Chromatography Tandem Mass Spectrometry: A Thorough Chromatographic Study
by Anastasia S. Kritikou, Marilena E. Dasenaki, Niki C. Maragou, Marios G. Kostakis and Nikolaos S. Thomaidis
Separations 2024, 11(9), 269; https://doi.org/10.3390/separations11090269 - 14 Sep 2024
Cited by 1 | Viewed by 957
Abstract
Τhyreostats (TSs) are veterinary drugs used in livestock farming for fattening. Their administration is banned in the European Union since 1981, and their monitoring for food quality and safety control requires sensitive and confirmatory methods. The present study describes the development and validation [...] Read more.
Τhyreostats (TSs) are veterinary drugs used in livestock farming for fattening. Their administration is banned in the European Union since 1981, and their monitoring for food quality and safety control requires sensitive and confirmatory methods. The present study describes the development and validation of a hydrophilic interaction liquid chromatography tandem mass spectrometry (HILIC-MS/MS) method for the simultaneous determination of 2-thiouracil (TU), 6-methyl-2-thiouracil (MTU), 6-propyl-2-thiouracil (PTU), 6-phenyl-2-thiouracil (PhTU), tapazole (TAP), and 2-mercaptobenzimidazole (MBI) in bovine muscle tissues. Investigation of the retention mechanism of the six analytes on the selected amide-based stationary phase showed that hydrophilic partition was the dominant interaction. The sample preparation included extraction with ACN/H2O (80/20), followed by dispersive solid-phase extraction (d-SPE) with C18 sorbent and hexane partitioning. The method was validated according to European guidelines using internal standards, including isotopically labelled ones. The method’s LODs ranged between 2.8 ng g−1 (6-phenyl-2-thiouracil) and 4.1 ng g−1 (2-thiouracil). Application of the proposed method to 48 bovine tissue samples showed non-detectable results. Full article
(This article belongs to the Special Issue Emerging Analytical Methods for Detection and Separation of Environmental Pollutants and Food Contaminants)
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21 pages, 1122 KiB  
Article
HS-SPME-GC-MS Analysis of the Volatile Composition of Italian Honey for Its Characterization and Authentication Using the Genetic Algorithm
by Carlotta Breschi, Francesca Ieri, Luca Calamai, Alessandra Miele, Silvia D’Agostino, Fabrizio Melani, Bruno Zanoni, Nadia Mulinacci and Lorenzo Cecchi
Separations 2024, 11(9), 266; https://doi.org/10.3390/separations11090266 - 10 Sep 2024
Cited by 1 | Viewed by 1668
Abstract
Honey’s chemical and sensory characteristics depend on several factors, including its botanical and geographic origins. The consumers’ increasing interest in monofloral honey and honey with a clear indication of geographic origin make these types of honey susceptible to fraud. The aim was to [...] Read more.
Honey’s chemical and sensory characteristics depend on several factors, including its botanical and geographic origins. The consumers’ increasing interest in monofloral honey and honey with a clear indication of geographic origin make these types of honey susceptible to fraud. The aim was to propose an original chemometric approach for honey’s botanical and geographic authentication purposes. The volatile fraction of almost 100 Italian honey samples (4 out of which are from Greece) from different regions and botanical origins was characterized using HS-SPME-GC-MS; the obtained data were combined for the first time with a genetic algorithm to provide a model for the simultaneous authentication of the botanical and geographic origins of the honey samples. A total of 212 volatile compounds were tentatively identified; strawberry tree honeys were those with the greatest total content (i.e., 4829.2 ng/g). A greater variability in the VOCs’ content was pointed out for botanical than for geographic origin. The genetic algorithm obtained a 100% correct classification for acacia and eucalyptus honeys, while worst results were achieved for honeydew (75%) and wildflower (60%) honeys; concerning geographic authentication, the best results were for Tuscany (92.7%). The original combination of HS-SPME-GC-MS analysis and a genetic algorithm is therefore proposed as a promising tool for honey authentication purposes. Full article
(This article belongs to the Special Issue Determination and Analysis of Volatiles by Solid Phase Microextraction, GC-MS, LC-MS and HPLC)
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14 pages, 1681 KiB  
Article
Prediction of Flavor Potential of Ocimum basilicum L. Side-Stream Phytoconstituents, Using Liquid Chromatography–Tandem Mass Spectrometry Analysis and In Silico Techniques
by Eftichia Kritsi, Thalia Tsiaka, Anna Boroboka, Garyfallia Koletsou, Spyridon Theofilatos, Artemis Maggenaki, Paris Christodoulou, Georgia Ladika, Konstantinos Tsiantas, Georgios Sotiroudis and Vassilia J. Sinanoglou
Separations 2024, 11(9), 261; https://doi.org/10.3390/separations11090261 - 3 Sep 2024
Cited by 1 | Viewed by 1512
Abstract
Although post-distillation side-streams of basil (Ocimum basilicum L.) pose significant economic and environmental challenges, they also bring forth new opportunities in the flavor industry. Thus, the objective of the current study was to assess the phenolic profile of basil side-stream extracts to [...] Read more.
Although post-distillation side-streams of basil (Ocimum basilicum L.) pose significant economic and environmental challenges, they also bring forth new opportunities in the flavor industry. Thus, the objective of the current study was to assess the phenolic profile of basil side-stream extracts to identify key compounds and to evaluate their taste properties, using liquid chromatography–tandem mass spectrometry (LC-MS/MS) analysis, flavor prediction tools and molecular docking. In particular, 52 phytoconstituents, mainly phenolic acids, salvianolic acids, flavonoids and fatty acids derivatives, were elucidated in the side-streams of two different basil varieties (Minimum and Genovese) harvested and distilled in early and late autumn, highlighting the effect of pre-harvest factors on basil’s phenolic fingerprint. Furthermore, the results of tests undertaken using taste prediction tools showed that most of the identified compounds were very likely to taste bitter, while six of them (caffeoylferuloyltartaric acid, isoquercetin, lithospermic acid A, sagerinic acid, salvianolic acids C and F) presented a high bitterant capacity (70–90%). Moreover, according to molecular docking studies, these compounds exhibited a stronger binding affinity to the hTAS2R46 bitter receptor compared to its known agonist, strychnine. This outcome and consequently their bitterness were mainly attributed to interactions with Glu265, Thr180 and/or Trp88 through the formation of direct hydrogen bonds. Therefore, the present results provide insights into the taste profiles of basil side-streams, leading to more sustainable and innovative uses of aromatic herbs residues. Full article
(This article belongs to the Special Issue Extraction and Characterization of Phenolic Compounds from Foods and Food Byproducts by Targeted and Untargeted LC-MS Methods)
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17 pages, 5134 KiB  
Article
Applications of Sample Preparation Techniques in the Analysis of New Psychoactive Substances
by Lorna A. Nisbet, Fiona M. Wylie and Karen S. Scott
Separations 2024, 11(9), 258; https://doi.org/10.3390/separations11090258 - 30 Aug 2024
Viewed by 1288
Abstract
The global rise of new psychoactive substances (NPSs) poses challenges for their analysis in biological matrices due to their complex chemistries and short market lifespan. A comparative study for the simultaneous extraction, separation, and detection of 19 NPSs was conducted. Six solid-phase extraction [...] Read more.
The global rise of new psychoactive substances (NPSs) poses challenges for their analysis in biological matrices due to their complex chemistries and short market lifespan. A comparative study for the simultaneous extraction, separation, and detection of 19 NPSs was conducted. Six solid-phase extraction (SPE) methods and one supported liquid extraction method (SLE) were compared for the extraction of analytes from blood, serum, plasma, and urine. Comparisons of four derivatization agents were conducted, at four temperatures and two incubation times. Extraction methods were assessed by precision, sensitivity, and extraction efficiency. Derivatizing agents were assessed on their selectivity and sensitivity, and a three-way ANOVA was conducted to determine statistical significance. CSDAU SPE cartridges were shown to be the most efficient when extracting analytes from blood, serum, and plasma, whereas Xcel I cartridges performed the strongest when extracting analytes from urine. SPE extraction efficiencies, when utilizing the best-performing cartridges, ranged from 49 to 119%. SLE successfully extracted all analytes from all matrices (ranging from 22 to 120%). Pentafluoropropionic anhydride: ethyl acetate was the most successful derivatizing agent, allowing all analytes to be detected, with the highest peak area responses and more unique spectra. The optimum temperature for incubation was 37 °C, with no statistical difference found between the two incubation times. Full article
(This article belongs to the Special Issue Forensic Toxicology: Biological Sampling and Development of Analytical Techniques)
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22 pages, 1699 KiB  
Review
Bioactive Compounds from Spirulina spp.—Nutritional Value, Extraction, and Application in Food Industry
by Blaženko Marjanović, Maja Benković, Tamara Jurina, Tea Sokač Cvetnić, Davor Valinger, Jasenka Gajdoš Kljusurić and Ana Jurinjak Tušek
Separations 2024, 11(9), 257; https://doi.org/10.3390/separations11090257 - 30 Aug 2024
Cited by 9 | Viewed by 9424
Abstract
The surging popularity of plant-based diets and the growing emphasis on clean-label products have intensified interest in Spirulina within the food industry. As more people adopt vegetarian, vegan, or flexitarian lifestyles, demand for plant-based protein sources has escalated. Spirulina’s high protein content [...] Read more.
The surging popularity of plant-based diets and the growing emphasis on clean-label products have intensified interest in Spirulina within the food industry. As more people adopt vegetarian, vegan, or flexitarian lifestyles, demand for plant-based protein sources has escalated. Spirulina’s high protein content and complete amino acid profile make it an ideal candidate to meet this demand. However, incorporating Spirulina into food products is not without its challenges. Its strong, earthy, or fishy taste can be off-putting to consumers and difficult to mask in food formulations. Furthermore, isolating Spirulina’s bioactive compounds while preserving their integrity is complex, especially considering the heat sensitivity of many of these components. Traditional extraction methods often employ high temperatures, which can degrade these valuable compounds. Consequently, there is a growing preference for non-thermal extraction techniques. This paper provides an overview of recent advancements in Spirulina cultivation, bioactive extraction, and their application in food products. Full article
(This article belongs to the Special Issue Extraction and Separation of Bioactive Molecules from Marine Flora and Fauna and By-Products of Aquatic Industries)
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16 pages, 3820 KiB  
Article
Simple Green Purification of Spilanthol from Natural Deep Eutectic Solvent and Ethanolic Acmella oleracea (L.) R.K. Jansen Extracts Using Solid-Phase Extraction
by Fabian Alperth, Sebastian Erhart, Olaf Kunert and Franz Bucar
Separations 2024, 11(8), 251; https://doi.org/10.3390/separations11080251 - 20 Aug 2024
Cited by 1 | Viewed by 2004
Abstract
Spilanthol is a major N-alkylamide constituent of Acmella oleracea (L.) R.K. Jansen with diverse pharmacological properties. We recently showed the applicability of NADES (natural deep eutectic solvents) for the green extraction of spilanthol. However, the purification of targets from NADES poses a [...] Read more.
Spilanthol is a major N-alkylamide constituent of Acmella oleracea (L.) R.K. Jansen with diverse pharmacological properties. We recently showed the applicability of NADES (natural deep eutectic solvents) for the green extraction of spilanthol. However, the purification of targets from NADES poses a challenging step due to their non-volatility. A simple green method to retrieve spilanthol with minimal instrumental effort was devised, fractioning NADES (choline chloride/methylurea, choline chloride/1,2-propanediol, choline chloride/citric acid) and dry ethanolic extracts by SPE on C18 material, eluting merely with ethanolic solutions. The relative distribution of spilanthol and organic adulteration in SPE fractions were detected by HPLC-DAD, followed by scale-up, quantification and purity determination in an NMR-based approach. Isocratic elution with 52% ethanol (v/v) proved suitable in all experiments. The three purest 10 mL fractions combined yielded 12.21 mg spilanthol at 71.65% purity from NADES extract ChCl/P (choline chloride/1,2-propanediol, molar ratio 1:2, +20% m/m water). Ethanolic extract samples showed purities ranging from 77.27 to 80.27% in combined raw fractions. For all samples, purity increased by removing non-soluble substances from organic solutions. Pooled NADES extract fractions showed 89.71% in final samples, ethanolic extracts 87.25 to 91.93%. The highest purities of individual fractions per extract were 89.23 to 94.15%. This cheap and simple purification process is promising to acquire spilanthol for research purposes or as a sample preparation step before HPLC on a semi-preparative to preparative scale, as the substance is highly priced and scarcely available on the market. Organic solvents can be reused, and preliminary scale-up possibilities are shown. Full article
(This article belongs to the Special Issue Extraction and Analysis of Chemical Compositions of Natural Products and Plants)
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