Separations

15 pages, 6707 KiB

Open AccessEditor’s ChoiceArticle

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 797

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)

► Show Figures

Graphical abstract

20 pages, 3734 KiB

Open AccessEditor’s ChoiceArticle

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 454

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)

► Show Figures

Figure 1

13 pages, 873 KiB

Open AccessEditor’s ChoiceArticle

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 818

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

► Show Figures

Figure 1

17 pages, 2312 KiB

Open AccessEditor’s ChoiceArticle

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 748

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)

► Show Figures

Figure 1

21 pages, 531 KiB

Open AccessEditor’s ChoiceReview

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 982

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

► Show Figures

Scheme 1

14 pages, 1399 KiB

Open AccessEditor’s ChoiceArticle

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 1016

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 (P_app 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)

► Show Figures

Figure 1

15 pages, 732 KiB

Open AccessEditor’s ChoiceArticle

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 636

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)

► Show Figures

Figure 1

22 pages, 3209 KiB

Open AccessEditor’s ChoiceReview

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 1 | Viewed by 900

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)

► Show Figures

Graphical abstract

30 pages, 2179 KiB

Open AccessEditor’s ChoiceReview

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 944

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)

► Show Figures

Figure 1

17 pages, 2691 KiB

Open AccessEditor’s ChoiceArticle

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

Viewed by 928

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)

► Show Figures

Figure 1

16 pages, 2546 KiB

Open AccessEditor’s ChoiceArticle

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 1001

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)

► Show Figures

Figure 1

13 pages, 1187 KiB

Open AccessEditor’s ChoiceArticle

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 988

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)

► Show Figures

Graphical abstract

17 pages, 3919 KiB

Open AccessEditor’s ChoiceArticle

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 1 | Viewed by 950

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)

► Show Figures

Figure 1

17 pages, 5104 KiB

Open AccessEditor’s ChoiceArticle

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 1494

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)

► Show Figures

Figure 1

13 pages, 4888 KiB

Open AccessEditor’s ChoiceArticle

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 1263

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)

► Show Figures

Graphical abstract

18 pages, 5440 KiB

Open AccessEditor’s ChoiceArticle

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 994

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 Q_max 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)

► Show Figures

Graphical abstract

12 pages, 1622 KiB

Open AccessEditor’s ChoiceArticle

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 1172

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)

► Show Figures

Figure 1

18 pages, 3713 KiB

Open AccessEditor’s ChoiceArticle

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 1054

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)

► Show Figures

Graphical abstract

17 pages, 2804 KiB

Open AccessEditor’s ChoiceArticle

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 1983

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)

► Show Figures

Graphical abstract

13 pages, 2048 KiB

Open AccessEditor’s ChoiceArticle

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 1042

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)

► Show Figures

Figure 1

17 pages, 4999 KiB

Open AccessEditor’s ChoiceArticle

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 1399

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)

► Show Figures

Graphical abstract

16 pages, 1893 KiB

Open AccessEditor’s ChoiceArticle

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

Viewed by 1485

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)

► Show Figures

Figure 1

12 pages, 1543 KiB

Open AccessEditor’s ChoiceArticle

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

Viewed by 942

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)

► Show Figures

Figure 1

15 pages, 2581 KiB

Open AccessEditor’s ChoiceArticle

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 840

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)

► Show Figures

Figure 1

21 pages, 1122 KiB

Open AccessEditor’s ChoiceArticle

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 1433

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)

► Show Figures

Figure 1

14 pages, 1681 KiB

Open AccessEditor’s ChoiceArticle

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

Viewed by 1317

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)

► Show Figures

Figure 1

17 pages, 5134 KiB

Open AccessEditor’s ChoiceArticle

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 1118

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)

► Show Figures

Figure 1

22 pages, 1699 KiB

Open AccessEditor’s ChoiceReview

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 4 | Viewed by 7057

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)

► Show Figures

Figure 1

16 pages, 3820 KiB

Open AccessEditor’s ChoiceArticle

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 1724

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)

► Show Figures

Figure 1

16 pages, 1297 KiB

Open AccessEditor’s ChoiceArticle

Polyphenols Extraction from Different Grape Pomaces Using Natural Deep Eutectic Solvents

by Alessandro Frontini, Andrea Luvisi, Carmine Negro, Massimiliano Apollonio, Rita Accogli, Mariarosaria De Pascali and Luigi De Bellis

Separations 2024, 11(8), 241; https://doi.org/10.3390/separations11080241 - 8 Aug 2024

Cited by 3 | Viewed by 2213

Abstract

Exploiting by-products from the oenological industry to extract antioxidant chemicals is a shared goal that combines the need to reduce the wine sector’s environmental impact with the need to improve the availability of these biomolecules, according to a circular economy approach. Natural deep [...] Read more.

Exploiting by-products from the oenological industry to extract antioxidant chemicals is a shared goal that combines the need to reduce the wine sector’s environmental impact with the need to improve the availability of these biomolecules, according to a circular economy approach. Natural deep eutectic solvents (NaDES) have recently captured researchers’ interest as a safer and more environmentally friendly alternative to traditional solvents due to their effectiveness, low toxicity, and stability. In this work, we set out to investigate several NaDES for the extraction of phenolic chemicals from local monovarietal grape pomace resulting from different vinification procedures (including both red and rosé vinification of Negroamaro and Primitivo grapes; rosé vinification of Susumaniello grapes and white vinification of Chardonnay, Fiano and Malvasia bianca grapes), with the additional goal of generalizing the use of NaDES to extract chemicals of interest from organisms selected from the wide plant biodiversity. Three binary choline chloride-based NaDES (DES-Lac, DES-Tar, and DES-Gly, with lactic acid, tartaric acid, and glycerol as hydrogen bond donors, respectively) were compared to ethanol as a conventional solvent, and the extracts were evaluated using HPLC/MS and colorimetric techniques. The results revealed that each NaDES produces a substantially higher total phenolic yield than ethanol (up to 127.8 mg/g DW from Primitivo rosé grape pomace). DES-Lac and DES-Tar were more effective for anthocyanins extraction; the most abundant compound was malvidin 3-O-glucoside (highest extraction yield with DES-Lac from Susumaniello pomace: 29.4 mg/g DW). Regarding phenolic compounds, DES-Gly was the most effective NaDES producing results comparable to ethanol. Unexpectedly, Chardonnay pomace has the greatest content of astilbin. In most cases, grape pomace extracts obtained by rosé and white vinification provided the maximum yield. As a result, NaDES have emerged as a viable alternative to traditional organic solvent extraction techniques, allowing for higher (or equal) yields while significantly lowering costs, hazards, and environmental impact. Full article

(This article belongs to the Special Issue Extraction and Characterization of Bioactive Compounds from Plant and Natural Sources)

► Show Figures

Figure 1

12 pages, 1288 KiB

Open AccessEditor’s ChoiceArticle

Evolution of Eight Biogenic Amines in Raw and Preserved Mackerel (Scomber scombrus) Fillets Monitored by UHPLC-PDA

by Laura Barp, Erica Moret and Sabrina Moret

Separations 2024, 11(8), 235; https://doi.org/10.3390/separations11080235 - 1 Aug 2024

Viewed by 926

Abstract

The presence of biogenic amines (BAs) in seafood can pose a health risk to consumers, as they have been linked to adverse reactions such as histamine poisoning. Although the only biogenic amine for which maximum limits have been set is histamine, it is [...] Read more.

The presence of biogenic amines (BAs) in seafood can pose a health risk to consumers, as they have been linked to adverse reactions such as histamine poisoning. Although the only biogenic amine for which maximum limits have been set is histamine, it is also important to regulate the presence of other amines associated with certain adverse effects. In this study, the official method for determining histamine was slightly modified and adapted for a UHPLC-PDA system and applied to analyze raw and preserved mackerel fillet samples. The evolution of biogenic amines during the storage period under refrigerated conditions revealed that, within two days, the limit for the content of histidine of 100 mg/kg was exceeded in raw fillets, while the histidine content in preserved mackerel (in oil and marinated) remained more stable. The thawing phase, whether in the fridge or at room temperature, did not significantly affect the BA content. Additionally, three different cooking methods (steaming, oven-baking, and boiling) significantly decrease the levels of BAs in highly contaminated raw mackerel fillets. Full article

(This article belongs to the Special Issue Determination of Potentially Toxic Elements in Food, Beverage and Medicinal Plants by Analytical Methods and Separation Technologies)

► Show Figures

Figure 1

16 pages, 5889 KiB

Open AccessEditor’s ChoiceArticle

LC-MS/MS-QTOF Identification of Phenolic Compounds of Sideritis Species Cultivated in Greece

by Eleftheria H. Kaparakou, Charalabos D. Kanakis, Maroula G. Kokotou, Georgios Papadopoulos and Petros A. Tarantilis

Separations 2024, 11(8), 229; https://doi.org/10.3390/separations11080229 - 26 Jul 2024

Cited by 1 | Viewed by 2673

Abstract

Phenolic compounds are plant secondary metabolites, one of the most common and widespread groups of substances in plants, as well as a major group of phytochemicals present in medicinal and aromatic plants. The phytochemical composition of the hydroalcoholic extracts from S. raeseri, [...] Read more.

Phenolic compounds are plant secondary metabolites, one of the most common and widespread groups of substances in plants, as well as a major group of phytochemicals present in medicinal and aromatic plants. The phytochemical composition of the hydroalcoholic extracts from S. raeseri, S. scardica and S. syriaca was determined by LC-MS/MS-QTOF analysis. A total amount of 23 secondary metabolites were identified, including 17 flavonoids (Fs), 4 phenylethanoid glycosides (PEGs), 1 phenolic acid (PA) and 1 fatty acid (FA). Among the three species, the constituents that have been detected in all of nine samples were: verbascocide/isoverbascoside (PEG), apigenin 7-O- glucoside (F), isoscutellarein 7-O-[6″-O-acetyl]-allosyl(1→2)-glucoside (F) and apigenin 7-(4″-p-coumaroylglucoside) (F). This study contributes to the phytochemical characterization of the Sideritis spp. by providing a comparative study of bioactive compounds present in three different Sideritis species, S. raeseri, S. scardica and S. syriaca, which are widely used as a herbal medicine in Mediterranean region and Balkan Peninsula. Full article

(This article belongs to the Special Issue Isolation and Identification of Biologically Active Natural Compounds)

► Show Figures

Figure 1

25 pages, 5094 KiB

Open AccessEditor’s ChoiceArticle

Extraction of Bioactive Compound-Rich Essential Oil from Cistus ladanifer L. by Microwave-Assisted Hydrodistillation: GC-MS Characterization, In Vitro Pharmacological Activities, and Molecular Docking

by Naoufal El Hachlafi, Fahd Kandsi, Amine Elbouzidi, Fatima Zahra Lafdil, Ghizlane Nouioura, Emad M. Abdallah, Rhizlan Abdnim, Mohamed Bnouham, Samiah Hamad Al-Mijalli, Hanae Naceiri Mrabti and Kawtar Fikri-Benbrahim

Separations 2024, 11(7), 199; https://doi.org/10.3390/separations11070199 - 27 Jun 2024

Cited by 4 | Viewed by 2255

Abstract

Cistus ladanifer L. is an aromatic and resinous perennial shrub commonly used in Moroccan folk medicine against a range of illnesses including skin problems, diabetes, diarrhea, and inflammation. The current investigation aims to determine the bioactive compounds of C. ladanifer essential oil (CL-Eo) [...] Read more.

Cistus ladanifer L. is an aromatic and resinous perennial shrub commonly used in Moroccan folk medicine against a range of illnesses including skin problems, diabetes, diarrhea, and inflammation. The current investigation aims to determine the bioactive compounds of C. ladanifer essential oil (CL-Eo) extracted by microwave-assisted hydrodistillation and their biological properties using in vitro and molecular docking approaches. The GC-MS analysis identified linderol (17.76%), gamma-terpinene (17.55%), and borneol (13.78%) as main bioactive compounds. CL-Eo significantly inhibited α-amylase (IC₅₀ = 0.41 ± 0.009 mg/mL), α-glucosidase (IC₅₀ = 0.49 ± 0.002 mg/mL) and lipase (IC₅₀ = 0.45 ± 0.004 mg/mL) enzymes. Moreover, CL-Eo showed significant hemoglobin glycation as well as antioxidant capacity as indicated by DPPH, ABTS, Frap and beta-carotene tests. The antimicrobial evaluation used disc-diffusion and microdilution tests in vitro. The results showed that CL-Eo had significant antibacterial activity, particularly against P. mirabilis (17.16 ± 1.04 mm), and moderate effects against L. innocua (13.48 ± 1.65 mm) and E. coli (12.47 ± 0.61 mm). In addition, it demonstrated potent antifungal activity against C. albicans (18.01 ± 0.91 mm) and C. tropicalis (16.45 ± 0.32 mm). The MIC and MBC tests provided confirmation that CL-Eo exhibited potent growth inhibition. The MIC ranged from 0.25 to 8.0% v/v and the MBC or MFC ranged from 0.25 to 16.0% v/v Eo. The tolerance level ratio showed bactericidal and fungicidal effects against tested microbial strains in varying degrees. According to these data, CL-Eo might be suggested as a promising candidate for drug development, specifically for combating candidiasis and diabetes. Full article

(This article belongs to the Special Issue Extraction, Purification and Application of Bioactive Compounds)

► Show Figures

Figure 1

11 pages, 1398 KiB

Open AccessEditor’s ChoiceArticle

A Novel Solvent Microextraction Lab-in-Syringe System Coupled with Atomic Absorption Spectrometry for Thallium Determination in Water Samples

by Arina Skok, Natalia Manousi, Yaroslav Bazel, Andriy Vishnikin and Aristidis Anthemidis

Separations 2024, 11(7), 193; https://doi.org/10.3390/separations11070193 - 21 Jun 2024

Cited by 2 | Viewed by 1277

Abstract

Thallium is an accumulative highly toxic metal, that can be present in environmental samples due to industrial pollution and is dangerous for living organisms. Thus, its determination at trace levels is necessary. The lab-in-syringe (LIS) is considered to be a simple, functional, and [...] Read more.

Thallium is an accumulative highly toxic metal, that can be present in environmental samples due to industrial pollution and is dangerous for living organisms. Thus, its determination at trace levels is necessary. The lab-in-syringe (LIS) is considered to be a simple, functional, and versatile, technique that combines operational concepts and flow and sequential injection analysis. In this study, a liquid-phase microextraction LIS system was developed as a front-end to flame atomic absorption spectrometry (FAAS) for the determination of thallium in water samples. The proposed approach is based on the formation of Tl(III) ammonium–pyrrolidine–dithiocarbamate complex followed by its extraction using di-isobutyl-ketone. These procedures take place within the syringe barrel of the LIS system. The limit of detection of the developed method was 2.1 µg L⁻¹ with a linear range from 7.0 to 400 µg L⁻¹. The relative standard deviation (RSD) was 3.9% (at 50.0 µg L⁻¹ Tl(I)), demonstrating good precision. Moreover, good method accuracy was obtained since the relative recovery values were within the range of 93.4–101.2%. Finally, reliable method applicability and green merits were demonstrated using the blue applicability grade index and green analytical procedure index, respectively. The proposed method was used for the analysis of environmental water samples. Full article

(This article belongs to the Section Purification Technology)

► Show Figures

Figure 1

16 pages, 804 KiB

Open AccessEditor’s ChoiceArticle

Simultaneous Determination of Multiresidues of Pesticides and Veterinary Drugs in Agricultural Soil Using QuEChERS and UHPLC–MS/MS

by Michele C. Vicari, Janice F. Facco, Sandra C. Peixoto, Gabriel S. de Carvalho, Luana Floriano, Osmar D. Prestes, Martha B. Adaime and Renato Zanella

Separations 2024, 11(6), 188; https://doi.org/10.3390/separations11060188 - 14 Jun 2024

Cited by 2 | Viewed by 1655

Abstract

Soil is one of the main destinations for pesticides and veterinary drugs used in agriculture and animal production. The negative consequences of the accumulation of these compounds in the environment make it important to monitor these compounds in the soil. In this study, [...] Read more.

Soil is one of the main destinations for pesticides and veterinary drugs used in agriculture and animal production. The negative consequences of the accumulation of these compounds in the environment make it important to monitor these compounds in the soil. In this study, we compared different extraction procedures using solvent shaking, ultrasound, or QuEChERS, and their combinations, for the simultaneous determination of 75 pesticide and seven veterinary drug residues in agricultural soil by ultra-high performance liquid chromatography coupled to serial mass spectrometry (UHPLC–MS/MS). The method using QuEChERS combined with shaking showed the best results for soil using the addition of water, followed by extraction with acetonitrile acidified with acetic acid and shaking in a shaker. For partitioning, anhydrous magnesium sulfate and anhydrous sodium acetate were used. The extract was centrifuged, filtered, and diluted (1:4, v/v) in water for determination by UHPLC–MS/MS. Method validation showed adequate accuracy and precision results, with recoveries between 70 and 120% and RSD ≤ 20% for the vast majority of the compounds evaluated at the spike levels of 10, 25, 50, and 100 μg kg⁻¹. The method limits of detection (LOD) and quantification (LOQ) ranged from 3.0 to 7.5 μg kg⁻¹ and from 10 to 25 μg kg⁻¹, respectively. The method was applied to different agricultural soil samples and proved to be efficient for routine analysis. Full article

(This article belongs to the Collection Feature Paper Collection in Section 'Environmental Separations')

► Show Figures

Graphical abstract

15 pages, 7166 KiB

Open AccessEditor’s ChoiceArticle

The Pollution Characteristics and Fate of Microplastics in Typical Wastewater Treatment Systems in Northern China

by Yi Ma, Zhenkang Bao, Shangying Cai, Qiong Wang, Beibei Dou, Xiangyu Niu, Qingzhen Meng, Penghao Li and Xiaoying Guo

Separations 2024, 11(6), 177; https://doi.org/10.3390/separations11060177 - 6 Jun 2024

Cited by 5 | Viewed by 1605

Abstract

This study focuses on the occurrence status and removal efficiency of microplastics in wastewater treatment plant processes. Analysis of effluent and sludge samples from the Wulongkou and Shuangqiao wastewater treatment plants in Zhengzhou revealed an overall microplastic removal efficiency of 95.64% and 92.53%, [...] Read more.

This study focuses on the occurrence status and removal efficiency of microplastics in wastewater treatment plant processes. Analysis of effluent and sludge samples from the Wulongkou and Shuangqiao wastewater treatment plants in Zhengzhou revealed an overall microplastic removal efficiency of 95.64% and 92.53%, respectively, indicating the effectiveness of wastewater treatment plants in reducing microplastic emissions. Microplastics primarily exist in forms such as fiber, fragment, floc, film, and grain. Fibers are predominant in the effluent of the Wulongkou plant, while fibers and films predominate in the effluent of the Shuangqiao plant. Moreover, microplastics are predominantly sized below 500 μm, with larger microplastics (2–5 mm) exhibiting higher removal efficiencies after secondary treatment. Analysis of microplastic types revealed that PE is the most common type in the effluent of the Wulongkou plant, while the Shuangqiao plant predominantly contains PE and PA66. The abundance of microplastics in sludge samples was found to be 6.4 ± 0.8 items/g and 11.3 ± 2.3 items/g, highlighting sludge as an important sink for microplastics. Surface analysis of microplastics revealed characteristics such as wrinkles and cracks, with energy-dispersive spectroscopy indicating significant adsorption of heavy metal elements such as Zn, Hg, and Pb onto microplastic surfaces in sludge. These findings underscore the importance of microplastic removal in wastewater treatment processes and provide scientific evidence for the control and management of microplastic pollution in the future. Full article

(This article belongs to the Special Issue Adsorption and Remediation of Emerging Pollutants from Water and Soil)

► Show Figures

Figure 1

14 pages, 3318 KiB

Open AccessEditor’s ChoiceArticle

Hyphenation of Thermodesorption into GC × GC-TOFMS for Odorous Molecule Detection in Car Materials: Column Sets and Adaptation of Second Column Dimensions to TD Pressure Constraints

by Romain Klein, José Dugay, Jérôme Vial, Didier Thiébaut, Guy Colombet, Donatien Barreteau and Guillaume Gruntz

Separations 2024, 11(6), 162; https://doi.org/10.3390/separations11060162 - 23 May 2024

Viewed by 1100

Abstract

Vehicle interior air quality is an issue of growing interest among car manufacturers and customers. GC-MS is the benchmark method for the analysis of indoor air or material emissions. It is suitable for the quantification of target pollutants and the most abundant compounds. [...] Read more.

Vehicle interior air quality is an issue of growing interest among car manufacturers and customers. GC-MS is the benchmark method for the analysis of indoor air or material emissions. It is suitable for the quantification of target pollutants and the most abundant compounds. It fails, however, to uncover the true molecular complexity of these samples. In the present study, we describe the development of a TD-GC × GC-TOFMS method designed to detect polar and potentially odorous molecules in car material emissions. Attention is paid to the hyphenation of the thermodesorber and the gas chromatograph, both at software and hardware levels, and the constraints due to pressure limitations on the thermodesorber (evaluated at 414 kPa/60 psi at the end of the temperature ramp and at 138 kPa/20 psi at rest). A compromise was made for the 2D column length and diameter to balance separation and pressure (50 × 0.18 × 0.18 cm × mm × µm + 60 cm transfer line selected). On various materials, we were able to observe several hundreds of polar molecules, among them were between 75 and 150 odorants per material. This work lays the foundation for the widespread screening of potential odorants in car material emissions. Full article

(This article belongs to the Collection Feature Paper Collection in Section ‘Chromatographic Separations’)

► Show Figures

Figure 1

20 pages, 739 KiB

Open AccessEditor’s ChoiceReview

Research Progress in the Separation of Chemical Components from Essential Oils by High-Speed Countercurrent Chromatography

by Linhong He, Zihao Zhong, Lijuan Zhang and Xi Bai

Separations 2024, 11(5), 152; https://doi.org/10.3390/separations11050152 - 15 May 2024

Cited by 2 | Viewed by 2129

Abstract

Essential oils (EOs) are vital secondary metabolites in plants. They have garnered substantial attention owing to their distinct flavors and desirable attributes, including potent antioxidant, antibacterial, and antitumor properties. Nevertheless, the active constituents of EOs exhibit intricate chemical structures, and conventional separation techniques [...] Read more.

Essential oils (EOs) are vital secondary metabolites in plants. They have garnered substantial attention owing to their distinct flavors and desirable attributes, including potent antioxidant, antibacterial, and antitumor properties. Nevertheless, the active constituents of EOs exhibit intricate chemical structures, and conventional separation techniques are inadequate for purifying the individual chemical components from EOs. High-speed countercurrent chromatography, based on the principles of a hydrodynamic equilibrium system, has emerged as a liquid–liquid chromatographic separation method renowned for its ability to handle substantial single injection volumes and the absence of irreversible adsorption. Consequently, in recent years, this technique has been widely employed in the isolation and refinement of natural products. In this review, a comprehensive analysis is conducted, contrasting the merits and demerits of high-speed countercurrent chromatography with conventional separation methods. The solvent systems, elution modes, commonly employed detectors, and practical applications are reviewed in the context of high-speed countercurrent chromatography for essential oil separation and purification. Furthermore, this review offers a glimpse into the potential prospects of applying this technique, with the intention of serving as a valuable reference for the use of high-speed countercurrent chromatography in the purification of EOs. Full article

(This article belongs to the Special Issue HPLC or Other Chromatographic-Based Methods for Analysis of Bioactive Compounds in Plant, Food, and Pharmaceutical Products)

► Show Figures

Figure 1

17 pages, 9132 KiB

Open AccessEditor’s ChoiceArticle

Aluminum Removal from Rare Earth Chloride Solution through Regulated Hydrolysis via Electrochemical Method

by Yaoyao Zhu, Jian Li, Dongyue Xie, Hui Zhang, Man Li, Binfeng Xu, Xuxia Zhang, Yangyang Xie and Tao Qi

Separations 2024, 11(5), 149; https://doi.org/10.3390/separations11050149 - 12 May 2024

Viewed by 2357

Abstract

Due to the coexistence of Al³⁺ and RE³⁺ and their similar properties, the separation of aluminum from rare earths is difficult. In this study, selective precipitation was used to separate aluminum from rare earth chloride solution via electrochemical regulated hydrolysis. By [...] Read more.

Due to the coexistence of Al³⁺ and RE³⁺ and their similar properties, the separation of aluminum from rare earths is difficult. In this study, selective precipitation was used to separate aluminum from rare earth chloride solution via electrochemical regulated hydrolysis. By controlling the current density and electrolytic time, the rate of hydroxyl ion production was regulated, and the selective separation of rare earth and aluminum was realized according to the different precipitation sequences. By altering the temperature, current density, pH value, and other parameters, the separation performance of aluminum from rare earth in mixed rare earth chloride systems was systematically investigated. The removal rate of aluminum reached 88.35%, and the loss rate of rare earth was only 5.99% under optimized conditions. Compared with traditional neutralization hydrolysis, the new process showed higher efficiency and lower rare earth loss rate. Furthermore, a kinetic analysis of aluminum precipitation revealed that the reaction adhered to pseudo-first order kinetics. Additionally, the precipitate obtained via separation and filtration was amorphous alumina hydroxide with a small amount of rare earth attached. No reagent was consumed for the new process, which was more efficient and cleaner, providing a new idea for removing aluminum impurities from rare earth solutions. Full article

(This article belongs to the Section Purification Technology)

► Show Figures

Figure 1

24 pages, 10774 KiB

Open AccessEditor’s ChoiceReview

Achievements in Preparation of Cyclodextrin–Based Porous Materials for Removal of Pollutants

by Kaiyue Bao, Anyun Zhang, Yiyao Cao and Lei Xu

Separations 2024, 11(5), 143; https://doi.org/10.3390/separations11050143 - 7 May 2024

Cited by 3 | Viewed by 1930

Abstract

Cyclodextrin–based porous materials have been widely applied in removing various organic pollutants from water environments, due to their unique physical and chemical properties, like the size–matching effect and hydrophobic interaction. Large numbers of hydroxyl groups in its external structure give cyclodextrin a high [...] Read more.

Cyclodextrin–based porous materials have been widely applied in removing various organic pollutants from water environments, due to their unique physical and chemical properties, like the size–matching effect and hydrophobic interaction. Large numbers of hydroxyl groups in its external structure give cyclodextrin a high solubility in water, but the existence of these hydroxyl groups also endows cyclodextrin with the ability to be chemically modified with various functional groups to reduce its solubility in water and, meanwhile, to develop some novel functionalized cyclodextrin–based porous materials for selective removal of the target organic pollutants. This review focuses on the recent development in the synthesis of cyclodextrin–based porous materials (crosslinked cyclodextrin polymers and immobilized cyclodextrins), as well as highlighting their applications and mechanisms in the removal of dyes, endocrine disruptors, and mixed pollutants from water. Finally, the challenges and future perspectives in related research fields are discussed. Full article

(This article belongs to the Special Issue Adsorption and Remediation of Emerging Pollutants from Water and Soil)

► Show Figures

Figure 1

18 pages, 8322 KiB

Open AccessEditor’s ChoiceArticle

Decoding the Volatile Profile of White Romanian Fetească Wines

by Fulvia-Ancuța Manolache, Denisa-Eglantina Duță, Gabriela Daniela Criveanu-Stamatie, Teodora-Alexandra Iordache and Maria-Cristina Todașcă

Separations 2024, 11(5), 141; https://doi.org/10.3390/separations11050141 - 3 May 2024

Cited by 3 | Viewed by 1720

Abstract

The wine’s volatilome, most of the time, defines not only its aroma, but also, its major attributes. In the case of wines, the authentication process has become imperative, in light of increased production of alcoholic beverages; consequently, reliable analytical methods have served for [...] Read more.

The wine’s volatilome, most of the time, defines not only its aroma, but also, its major attributes. In the case of wines, the authentication process has become imperative, in light of increased production of alcoholic beverages; consequently, reliable analytical methods have served for it. Therefore, the goal of this research was to establish the global volatile profile of traditional Romanian white wines from Fetească varieties (Fetească albă, Fetească regală) in order to identify its unique characteristics by means of a headspace solid-phase microextraction coupled with gas chromatography analysis (HS-SPME/GC-MS) and e-Nose devoted techniques. Statistics was also employed aimed at differentiating the analyzed wine by varietal groups. Consequently, 23 volatile compounds were detected and quantified in 39 Fetească white wine samples originating from various production areas (Muntenia, Oltenia, Transylvania, Banat and Dobrogea), then further classified according to their odor thresholds in five aromatic classes (floral, fruity, sweet, lactic (cheesy) and other). In addition, statistics (Principal Component Analysis (PCA), Hieratical Clustering Analysis (HCA)) were used aiming to differentiate the analyzed varietal groups. The outcomes have pointed out the existence of distinct clusters connected with ethyl esters or alcohol composition and production year, depending on each examined variety. Full article

(This article belongs to the Topic Advances in Analysis of Food and Beverages)

► Show Figures

Figure 1

12 pages, 1710 KiB

Open AccessEditor’s ChoiceArticle

Pomegranate Juice Clarification Using Ultrafiltration: Influence of the Type of Variety and Degree of Ripeness

by Asunción M. Hidalgo, José A. Macario, Marta Abellán-Baeza, Teresa Sánchez-Moya, Rubén López-Nicolás and Fulgencio Marín-Iniesta

Separations 2024, 11(5), 134; https://doi.org/10.3390/separations11050134 - 26 Apr 2024

Viewed by 2035

Abstract

Fruit consumption guarantees the supply of most of the necessary nutrients for a complete and balanced diet, as it is a relevant source of vitamins, minerals, and antioxidants. In particular, pomegranate has very interesting medicinal properties, such as an anti-inflammatory effect and the [...] Read more.

Fruit consumption guarantees the supply of most of the necessary nutrients for a complete and balanced diet, as it is a relevant source of vitamins, minerals, and antioxidants. In particular, pomegranate has very interesting medicinal properties, such as an anti-inflammatory effect and the protection of the cardiovascular system, among others. During pomegranate juice production, it appears cloudy and must be clarified to remove suspended solids such as colloids and high-molecular weight tannins. The membrane clarification process is a cost-effective alternative to the conventional methods, resulting in a high-quality product. In this work, the clarification of pomegranate juice using the Triple System Model F1 membrane module was carried out for the Mollar and Wonderful varieties with early and late maturity. Three ultrafiltration membranes with different molecular weight cut-off and different chemical compositions were used. The rejection coefficient and permeate flux (which represent the selectivity of the membranes and the process efficiency, respectively) were measured. GR-40PP showed the best results in terms of membrane selectivity and process efficiency, achieving adequate physicochemical juice parameters. Regarding the comparison of the maturity degree, in general terms, the Mollar variety showed better results. Ripe pomegranates showed greater selectivity, while the process efficiency was higher for the early samples. Full article

(This article belongs to the Section Analysis of Natural Products and Pharmaceuticals)

► Show Figures

Graphical abstract

19 pages, 4852 KiB

Open AccessEditor’s ChoiceArticle

Adsorption of Fluoride from Water Using Aluminum-Coated Silica Adsorbents: Comparison of Silica Sand and Microcrystalline Silica

by Kiana Modaresahmadi, Amid P. Khodadoust and James Wescott

Separations 2024, 11(4), 125; https://doi.org/10.3390/separations11040125 - 19 Apr 2024

Cited by 1 | Viewed by 1934

Abstract

Two aluminum-coated silica adsorbents were evaluated using silica sand and microcrystalline silica as aluminum-oxide-based adsorbents with different crystalline silica base materials. The aluminum coating contained mainly amorphous aluminum oxides for both aluminum-coated silica adsorbents. The adsorption of fluoride onto both adsorbents was favorable [...] Read more.

Two aluminum-coated silica adsorbents were evaluated using silica sand and microcrystalline silica as aluminum-oxide-based adsorbents with different crystalline silica base materials. The aluminum coating contained mainly amorphous aluminum oxides for both aluminum-coated silica adsorbents. The adsorption of fluoride onto both adsorbents was favorable according to the Langmuir and Freundlich adsorption equations, while the physical adsorption of fluoride occurred for both adsorbents according to the Dubinin–Raduskevish (D-R) equation. The adsorption of fluoride was stronger for aluminum-coated silica sand based on adsorption parameters from the Langmuir, Freundlich, and D-R adsorption equations, with the stronger binding of fluoride likely due to the observed greater specific adsorption. The adsorption capacity determined using the Langmuir equation was about 7 times greater for aluminum-coated microcrystalline silica primarily due to the 1.22-orders-of-magnitude-larger surface area of aluminum-coated microcrystalline silica, whereas the surface-normalized adsorption capacity was 2.4 times greater for aluminum-coated silica sand, possibly due to more aluminum being present on the surface of silica sand. Fluoride adsorption occurred over a broad pH range from 3 to 10 for both adsorbents, with nearly the same pH_PZC of 9.6, while aluminum-coated microcrystalline silica displayed a higher selectivity for fluoride adsorption from different natural water sources. Full article

(This article belongs to the Section Materials in Separation Science)

► Show Figures

Figure 1

24 pages, 5748 KiB

Open AccessEditor’s ChoiceReview

Laser Manufacturing of Superwetting Oil–Water Separation Materials: A Review

by Wei Xiong, Linfeng Zhu, Ruisong Jiang and Chaolang Chen

Separations 2024, 11(4), 126; https://doi.org/10.3390/separations11040126 - 19 Apr 2024

Cited by 6 | Viewed by 2361

Abstract

The frequent occurrence of oil spills and the massive discharge of oily wastewater pose a significant threat to sustainable and healthy human development. Therefore, it is of importance to effectively separate oil–water mixtures. Inspired by nature, many superwetting surfaces/materials for oil–water separation have [...] Read more.

The frequent occurrence of oil spills and the massive discharge of oily wastewater pose a significant threat to sustainable and healthy human development. Therefore, it is of importance to effectively separate oil–water mixtures. Inspired by nature, many superwetting surfaces/materials for oil–water separation have been developed in recent years. However, these surfaces/materials are subject to certain limitations and are unable to fully meet practical needs. With the advancement of laser technology, a novel solution has been provided for fabricating superwetting oil–water separation materials. Based on the design theory and separation mechanism, this paper summarizes the research progress of the laser-fabricated superwetting surfaces/materials for oil–water separation in recent years. First, the basic wetting theory, design strategy, and oil–water separation mechanism of the laser-fabricated materials are introduced in detail. Subsequently, the laser-fabricated oil–water separation materials, including superoleophilic/superhydrophobic materials, superhydrophilic/superoleophobic materials, and materials with reversible or superamphiphilic wettability, are systematically summarized and analyzed. Finally, the challenges and future research directions of laser-fabricated superwetting oil–water separation materials are discussed. Full article

(This article belongs to the Special Issue Advanced Oil–Water Separation Technology)

► Show Figures

Graphical abstract

15 pages, 2394 KiB

Open AccessEditor’s ChoiceArticle

Selective H₂ Evolution and CO₂ Absorption in Electrolysis of Ethanolamine Aqueous Solutions

by Satoshi Fukada, Ryosuke Sakai, Makoto Oya and Kazunari Katayama

Separations 2023, 10(11), 578; https://doi.org/10.3390/separations10110578 - 20 Nov 2023

Viewed by 2149

Abstract

Selective H₂ evolution and CO₂ absorption in several ethanolamine aqueous solutions are comparatively investigated using a new electrolysis reactor. H₂ bubbles are generated from a cathode in any ethanolamine electrolyte, and its experimental gas evolution rates are correlated by Faraday’s [...] Read more.

Selective H₂ evolution and CO₂ absorption in several ethanolamine aqueous solutions are comparatively investigated using a new electrolysis reactor. H₂ bubbles are generated from a cathode in any ethanolamine electrolyte, and its experimental gas evolution rates are correlated by Faraday’s first rule. No or smaller amounts of CO₂ and N₂ bubbles than stoichiometric ones are generated on an anode through the reaction between hydroxide ions and ethanolamine ones. No CO or O₂ is observed in the system exhaust, and most of the CO₂, along with N_2, is still absorbed in ethanolamine aqueous solutions with the addition of KOH and/or HCOOH under high pH conditions. Variations of the concentrations of coexisting ions dissolved in the electrolytes of mono- or tri-ethanolamine (MEA or TEA) and ethylenediamine (EDA) solutions with CO₂ absorption are calculated using the equilibrium constants to relate the concentrations of solute ions. Electric resistivities of the ethanolamine aqueous solutions are correlated by the pH value and are analyzed in terms of equilibrium constants among the concentrations of coexisting ions. Conditions of the MEA electrolyte to achieve high-performance electrolysis is discussed for selective H₂ generation. Full article

(This article belongs to the Special Issue Advances in CO₂ Adsorptive Separation for CO₂ Capture)

► Show Figures

Figure 1

16 pages, 3907 KiB

Open AccessEditor’s ChoiceArticle

Identifying the Early Post-Mortem VOC Profile from Cadavers in a Morgue Environment Using Comprehensive Two-Dimensional Gas Chromatography

by Darshil Patel, Rushali Dargan, Wesley S. Burr, Benoit Daoust and Shari Forbes

Separations 2023, 10(11), 566; https://doi.org/10.3390/separations10110566 - 10 Nov 2023

Cited by 2 | Viewed by 3358

Abstract

Understanding the VOC profile released during the early post-mortem period is essential for applications in training human remains detection dogs and urban search and rescue operations (USAR) to rapidly locate living and deceased victims. Human cadavers were sampled at the UQTR morgue within [...] Read more.

Understanding the VOC profile released during the early post-mortem period is essential for applications in training human remains detection dogs and urban search and rescue operations (USAR) to rapidly locate living and deceased victims. Human cadavers were sampled at the UQTR morgue within a 0–72 h post-mortem interval. VOC samples were collected from the headspace above the cadavers, using Tenax TA/Carbograph 5TD dual sorbent tubes, and analyzed using GC×GC-TOFMS. Multiple data processing steps, including peak table alignment and filtering, were undertaken using LECO ChromaToF and custom scripts in R programming language. This study identified 104 prevalent VOCs, some of which are linked to human decomposition, while others are connected to the persistence of living scent. Principal Component Analysis (PCA) further highlighted that VOC profiles can change dynamically over time, even in a controlled setting. The findings underscore the complexity and variability in VOC profiles during the early post-mortem period. This variability is influenced by multiple factors including the individual’s biological and physiological conditions. Despite the challenges in characterizing these profiles, the identified VOCs could potentially serve as markers in forensic applications. The study also highlights the need for additional research to build a dataset of VOCs for more robust forensic applications. Full article

(This article belongs to the Special Issue Chemical Separations in Criminalistics)

► Show Figures

Figure 1

25 pages, 4971 KiB

Open AccessEditor’s ChoiceArticle

Evaluation of CO₂ Adsorption Parameters in Fluidised Zeolite 13X Beds Using Non-Linear Multivariate Optimisation

by Alessio Caravella, Giuseppe Prenesti, Salvatore De Luca, Maria Turano, Flaviano Testa and Rossella Girimonte

Separations 2023, 10(11), 558; https://doi.org/10.3390/separations10110558 - 3 Nov 2023

Cited by 2 | Viewed by 4142

Abstract

This work is part of a research project aimed at studying potential sorbents for CO₂ capture. The main parameters characterising the adsorption process of zeolite 13X were derived with the aim of overcoming the limits of experimental analysis and thus predicting the [...] Read more.

This work is part of a research project aimed at studying potential sorbents for CO₂ capture. The main parameters characterising the adsorption process of zeolite 13X were derived with the aim of overcoming the limits of experimental analysis and thus predicting the performances of the materials of interest. In particular, the main parameters that control the adsorption process of CO₂ in zeolite 13X were evaluated through parametric optimisation. This systematic procedure allows for the prediction of the performances of the materials at different operating conditions, identifying the most suitable ones for the case under consideration. Another important application lies in the possibility of a preliminary study of a potential process scale-up for future industrial use. The captured carbon dioxide can be stored or used as a reagent in the production of products with higher economic values, such as methanol, DME and others. Full article

(This article belongs to the Special Issue Advances in CO₂ Adsorptive Separation for CO₂ Capture)

► Show Figures

Figure 1

21 pages, 3743 KiB

Open AccessEditor’s ChoiceArticle

A Rule-Based Automated Chemical Recognition Algorithm for a Multi-Cell Multi-Detector Micro Gas Chromatograph

by Qu Xu, Yutao Qin and Yogesh B. Gianchandani

Separations 2023, 10(11), 555; https://doi.org/10.3390/separations10110555 - 31 Oct 2023

Cited by 1 | Viewed by 2036

Abstract

A chemical recognition algorithm is an integral part of any autonomous microscale gas chromatography (µGC) system for automated chemical analysis. For a multi-detector µGC system, the chemical analysis must account for the retention time of each chemical analyte as well as the relative [...] Read more.

A chemical recognition algorithm is an integral part of any autonomous microscale gas chromatography (µGC) system for automated chemical analysis. For a multi-detector µGC system, the chemical analysis must account for the retention time of each chemical analyte as well as the relative response of each detector to each analyte, i.e., the detector response pattern (DRP). In contrast to the common approaches of heuristically using principal component analysis and machine learning, this paper reports a rule-based automated chemical recognition algorithm for a multi-cell, multi-detector µGC system, in which the DRP is related to theoretical principles; consequently, this algorithm only requires a small amount of calibration data but not extensive training data. For processing both the retention time and the raw DRP, the algorithm applies rules based on expert knowledge to compare the detected peaks; these rules are located in a customized software library. Additionally, the algorithm provides special handling for chromatogram peaks with a small signal-to-noise ratio. It also provides separate special handling for asymmetrical peaks that may result from surface adsorptive analytes. This work also describes an experimental evaluation in which the algorithm used the relative response of two complementary types of capacitive detectors as well as a photoionization detector that were incorporated into the µGC system of interest. In these tests, which were performed on chromatograms with 21–31 peaks for each detector, the true positive rate was 96.3%, the true negative rate was 94.1%, the false positive rate was 5.9%, and the false negative rate was 3.7%. The results demonstrated that the algorithm can support µGC systems for automated chemical screening and early warning applications. Full article

(This article belongs to the Special Issue Development of Materials for Chromatographic Separation)

► Show Figures

Figure 1

15 pages, 2776 KiB

Open AccessEditor’s ChoiceArticle

Application of Choline Chloride-Based Deep Eutectic Solvents in the Synthesis of Hydrazones

by Valentina Bušić, Sunčica Roca and Dajana Gašo-Sokač

Separations 2023, 10(11), 551; https://doi.org/10.3390/separations10110551 - 29 Oct 2023

Cited by 4 | Viewed by 3367

Abstract

The synthesis of 14 hydrazone compounds derived from pyridoxal, pyridine-4-carbaldehyde, and quinoline-2-carbaldehyde using two methods, conventional method in deep eutectic solvents (DESs) and effective combination of ultrasound and DESs, is presented in this paper. In addition, the possibility of using 12 choline chloride [...] Read more.

The synthesis of 14 hydrazone compounds derived from pyridoxal, pyridine-4-carbaldehyde, and quinoline-2-carbaldehyde using two methods, conventional method in deep eutectic solvents (DESs) and effective combination of ultrasound and DESs, is presented in this paper. In addition, the possibility of using 12 choline chloride (ChCl)-based DESs as an alternative to organic solvents was investigated. The results show that the application of ultrasound not only improves the reaction yield but also shortens the reaction time. The prepared compounds synthesized at room temperature were analyzed via NMR spectroscopy and MS spectrometry. The studies confirmed that the DESs ChCl:malonic, oxalic, levulinic, and trans-cinnamic acid can be excellent alternatives to classical organic solvents. By the combined use of DESs and the ultrasonic method, compound 11 was obtained in a nearly quantitative yield of 98% in DES ChCl:oxalic acid. The advantages of using DESs as reaction media are that they are biodegradable, nontoxic, recyclable, and can be easily prepared with inexpensive starting materials. The results of recycling DESs show that they can be used up to the fourth recycling cycle without significantly changing the reaction yield. Full article

(This article belongs to the Special Issue Application of Deep Eutectic Solvents in Green Separation Chemistry)

► Show Figures

Figure 1

22 pages, 856 KiB

Open AccessEditor’s ChoiceArticle

Aroma Profile of Grapevine Chips after Roasting: A Comparative Study of Sorbara and Spergola Cultivars for More Sustainable Oenological Production

by Veronica D’Eusanio, Lorenzo Morelli, Andrea Marchetti and Lorenzo Tassi

Separations 2023, 10(10), 532; https://doi.org/10.3390/separations10100532 - 6 Oct 2023

Cited by 4 | Viewed by 2118

Abstract

This study aimed to compare the aroma profiles of Sorbara and Spergola grapevine prunings roasted at different temperatures (120, 140, 160, 180, 200, and 240 °C). One potential application of grapevine prunings is their use as infusion chips to enhance and improve the [...] Read more.

This study aimed to compare the aroma profiles of Sorbara and Spergola grapevine prunings roasted at different temperatures (120, 140, 160, 180, 200, and 240 °C). One potential application of grapevine prunings is their use as infusion chips to enhance and improve the aging processes of alcoholic beverages and vinegars. Aromatic compounds impart unique flavors and contribute to the complexity of the final products. Thermogravimetry–mass spectrometry coupled with evolved gas analysis (TGA-MS-EGA) was conducted to identify the thermal steps at which substantial changes occurred in the wood matrix. Solid-phase microextraction–gas chromatography–mass spectrometry (SPME-GC-MS) was used for the analysis of volatile compounds. Several key volatile compounds were identified, showing variations in their concentrations as a function of cultivar and roasting temperature. Furan derivatives, such as furfural, and phenolic compounds, such as guaiacol and vanillin, were the two main chemical classes of volatile compounds that predominantly defined the aroma of grapevine chips roasted above 180 °C. At lower roasting temperatures, some aldehydes, such as hexanal and terpenes, defined the aroma profiles of the samples. By repurposing waste materials, this application offers a pathway for environmentally conscious viticulture and sustainable practices within the food industry. Full article

► Show Figures

Figure 1

Journal Menu

Journal Browser

Editor’s Choice Articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI