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Separations, Volume 11, Issue 2 (February 2024) – 28 articles

Cover Story (view full-size image): The extraction of substances with potential applications in the food, pharmaceutical, and cosmetic industries is the subject of increased research interest. Ultrasonic extraction as an environmentally friendly "green" method is one of the most preferred for isolating biologically active compounds from plants. It is economical and saves time while producing high-quality extracts. On the other hand, with microwave extraction, the process is significantly accelerated, which is due to the thermal effect caused by microwaves. This, in turn, carries the risk of destructive processes that can affect the extractable substance due to the rapid increase in temperature. In this study, ultrasonic and microwave extraction were used to obtain phycocyanin from Spirulina, and the advantages of both techniques were demonstrated. View this paper
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30 pages, 1718 KiB  
Review
Nanofiltration-Assisted Concentration Processes of Phenolic Fractions and Carotenoids from Natural Food Matrices
by Roberto Castro-Muñoz
Separations 2024, 11(2), 64; https://doi.org/10.3390/separations11020064 - 19 Feb 2024
Cited by 1 | Viewed by 1147
Abstract
In new food formulations, carotenoids and phenolic compounds are likely to be the most sought after food ingredients according to their bioactivity, nutraceutical, nutritional value, and compatibility properties once incorporated into food formulations. Such solutes are naturally present in many plant-based sources, and [...] Read more.
In new food formulations, carotenoids and phenolic compounds are likely to be the most sought after food ingredients according to their bioactivity, nutraceutical, nutritional value, and compatibility properties once incorporated into food formulations. Such solutes are naturally present in many plant-based sources, and some portions are directly consumed when enriching food products and formulations; however, some portions, which are contained in the parts of the plant sources not considered edible, including the leaves, peel, and seeds, among other by-products, are commonly wasted. Related to this, scientists have found a new window for obtaining these bioactive molecules, but their recovery remains a challenge. To some extent, the final purification and polishing requires highly selective performance to guarantee the desired properties and concentration. In this regard, membrane technologies, such as nanofiltration (NF), represent an alternative, owing to their highly selective properties when separating low-molecular-weight compounds. NF becomes immediately suitable when the pretreated extracts are subjected to further efficient concentration, fractionation, and polishing of phenolic fractions and carotenoids. The separation efficiency (usually higher than 97%) of NF technology is high according to the low pore size of NF membranes, but the low temperature in process separation also contributes to the separation of thermolabile compounds. Therefore, this paper reviews the ongoing cases of studies reporting the successful separation and polishing of phenolic fractions and carotenoids from distinct sources. In particular, we have focused our attention on the main interactions during the separation process and the drawbacks and advantages of using membranes for such a case study. Full article
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15 pages, 3877 KiB  
Article
Efficient Removal of Tetracycline by Metal–Organic Framework ZIF-67 and Its Mechanism
by Shengyang Zheng, Yaping Xu, Xu Yao, Chenzhe Wang, Ping Liu, Haitao Zhao, Jianbing Lu and Jing Ju
Separations 2024, 11(2), 63; https://doi.org/10.3390/separations11020063 - 18 Feb 2024
Viewed by 916
Abstract
The widespread use of tetracycline (TC) poses potential hazards to ecosystems and human health. In this study, ZIF-67 was successfully synthesized using a room-temperature static synthesis method and applied to the efficient removal of TC from water. It was shown that the maximum [...] Read more.
The widespread use of tetracycline (TC) poses potential hazards to ecosystems and human health. In this study, ZIF-67 was successfully synthesized using a room-temperature static synthesis method and applied to the efficient removal of TC from water. It was shown that the maximum adsorption of TC by ZIF-67 could reach 1583.128 mg·g−1 at pH = 5.0, an initial TC concentration of 450 mg·g−1, an adsorption time of 720 min, and a temperature of 308K.The pseudo-second-order kinetic model and Langmuir’s isothermal adsorption model could describe the adsorption process better, which proved that the adsorption of ZIF-67 on TC was mainly monolayer adsorption dominated by chemisorption. Mechanistic studies showed that the adsorption process of ZIF-67 on TC was mainly through electrostatic interactions, pore adsorption, π–π interactions, and framework coordination of ZIF-67 surface cations with TC. Full article
(This article belongs to the Special Issue Removal of Emerging Pollutants and Environmental Analysis)
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11 pages, 707 KiB  
Article
Essential Oils from Azorean Cryptomeria japonica Female Cones at Different Developmental Stages: Variations in the Yields and Chemical Compositions
by Alexandre Janeiro, Ana Lima, Filipe Arruda, Tanner Wortham, Tânia Rodrigues, José Baptista and Elisabete Lima
Separations 2024, 11(2), 62; https://doi.org/10.3390/separations11020062 - 18 Feb 2024
Cited by 1 | Viewed by 945
Abstract
Cryptomeria japonica (Thunb. ex L.f.) D. Don (Cupressaceae) is widely cultivated in the Azores archipelago (Portugal) for landscaping and timber production, generating a huge amount of biomass residues. Among these, female cones (FC) emerge as a source of particularly valuable essential oils (EOs), [...] Read more.
Cryptomeria japonica (Thunb. ex L.f.) D. Don (Cupressaceae) is widely cultivated in the Azores archipelago (Portugal) for landscaping and timber production, generating a huge amount of biomass residues. Among these, female cones (FC) emerge as a source of particularly valuable essential oils (EOs), namely, as promising broad-spectrum antimicrobial agents. However, phytochemical research on C. japonica FC EOs remains scarce. This study evaluated the EO yields and chemical compositions of immature and mature FC (IFC and MFC) from the same batch of Azorean C. japonica. IFC and MFC EOs, obtained via hydrodistillation, presented different yields (0.72% vs. 1.12% w/w, dry weight), and their composition, determined via gas chromatography/mass spectroscopy, revealed that the monoterpenes class was dominant (51.84% vs. 69.13%), followed by the sesquiterpenes (36.44% vs. 26.28%) and diterpenes (10.96% vs. 3.03%) classes. However, the correspondent oxygen-containing terpenes classes were 1.5–2.0 times higher in IFC. Thus, the maturation process revealed an increase in EO yield and α-pinene content (19.5% vs. 41.3%) but a decrease in other important bioactive terpenes/terpenoids (terpinen-4-ol, bornyl acetate, elemol, γ-eudesmol, phyllocladene, and nezukol) content. In conclusion, IFC and MFC EOs, due to their unique composition, may have differential commercial applications and, consequently, contribute to increasing the commercial potential of C. japonica’s EO industry. Full article
(This article belongs to the Section Analysis of Natural Products and Pharmaceuticals)
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23 pages, 9681 KiB  
Article
Phyto-Mediated Green Synthesis of Silver Nanoparticles Using an Aqueous Leaf Extract of Momordica cymbalaria: Antioxidant, Cytotoxic, Antibacterial, and Photocatalytic Properties
by Madasamy Sundar, Gopalan Rajagopal, Ambikapathi Nivetha, Seetharaman Prabu Kumar and Selvaraj Muthukumar
Separations 2024, 11(2), 61; https://doi.org/10.3390/separations11020061 - 17 Feb 2024
Viewed by 1190
Abstract
In this study, we biosynthesized the stable silver nanoparticles (AgNPs) from Momordica cymbalaria leaves to evaluate their antioxidant, antibacterial, cytotoxic, and photocatalytic properties. Initially, we screened the bioactive compounds from M. cymbalaria extract using GC-MS. The biosynthesis of Mc-AgNPs was confirmed using [...] Read more.
In this study, we biosynthesized the stable silver nanoparticles (AgNPs) from Momordica cymbalaria leaves to evaluate their antioxidant, antibacterial, cytotoxic, and photocatalytic properties. Initially, we screened the bioactive compounds from M. cymbalaria extract using GC-MS. The biosynthesis of Mc-AgNPs was confirmed using instruments, such as UV-visible spectroscopy FT-IR, XRD, SEM with EDX, and HR-TEM analyses. The UV-visible spectrum indicated absorbance at 425 nm. The crystallite size of the M. cymbalaria-stabilized nanoparticles was determined to be 20.14 nm. The morphology and size of the synthesized Mc-AgNPs were confirmed via SEM-EDX and HR-TEM analyses, with a size range from 16 to 22 nm. The synthesized Mc-AgNPs exhibited a photocatalytic yield of 60%. The biosynthesized Mc-AgNPs demonstrated strong antioxidant properties and prominent antibacterial activity against human pathogenic bacteria. The cytotoxicity study revealed that Mc-AgNPs were effective against MCF-7 cells in a dose-dependent manner. The recognized bioactivities confirm that the synthesized Mc-AgNPs act as effective catalysts in oxidation and serve as potent antioxidant, anticancer, and antibacterial agents. Full article
(This article belongs to the Section Materials in Separation Science)
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14 pages, 1315 KiB  
Article
Optimization of the Reaction between 5-O-Caffeoylquinic Acid (5-CQA) and Tryptophan—Isolation of the Product and Its Evaluation as a Food Dye
by Patroklos Vareltzis, Panagiota Karatsioli, Ioannis Kazakos, Anna-Maria Menelaou, Konstantina Parmaxi and Vangelis Economou
Separations 2024, 11(2), 60; https://doi.org/10.3390/separations11020060 - 16 Feb 2024
Viewed by 1119
Abstract
The food industry is seeking a stable, non-toxic red dye as a substitute for synthetic pigments. This can result from the reaction between 5-O-Caffeoylquinic acid (5-CQA) and tryptophan (TRP). This study explores the reaction kinetics under ultrasound conditions and investigates reaction parameters, such [...] Read more.
The food industry is seeking a stable, non-toxic red dye as a substitute for synthetic pigments. This can result from the reaction between 5-O-Caffeoylquinic acid (5-CQA) and tryptophan (TRP). This study explores the reaction kinetics under ultrasound conditions and investigates reaction parameters, such as pH, temperature, and reactants’ concentrations, to accelerate the reaction. At the end of the reaction, the solution was either spray-dried or acidified to isolate the pigment, which was evaluated for its potential as a food dye. Using ultrasound at 40 °C led to a significant acceleration of the reaction that was completed in 8.5 h, marking a 300% improvement compared to literature. The caffeic acid, and not the quinic acid, moiety of 5-CQA seems to be partly responsible for the formation of the red pigment. The pH had a profound impact on the reaction rate, with an optimal value of pH = 9.5. Increased TRP concentrations led to increased reaction rates, while higher 5-CQA concentrations led to significant deviations from redness (a* value). The pigment, lacking significant antimicrobial activity, exhibited remarkable thermal stability (pH 3–9), delaying food oxidation and color deterioration. The results indicate that the reaction can be significantly accelerated by ultrasound, which will be useful for the scale-up of the process and giving the produced pigment the potential for use as an alternative to artificial coloring. Full article
(This article belongs to the Special Issue Bioactive Compounds in Foods: Separation, Extraction and Application)
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17 pages, 4728 KiB  
Article
Stability and Reactivity of Guaiacylglycerol-β-Guaiacyl Ether, a Compound Modeling β-O-4 Linkage in Lignin
by Zeinab Rabiei, Andrew Simons, Magdalena Folkmanova, Tereza Vesela, Ondrej Uhlik, Evguenii Kozliak and Alena Kubátová
Separations 2024, 11(2), 59; https://doi.org/10.3390/separations11020059 - 14 Feb 2024
Viewed by 974
Abstract
Lignin, a complex and abundant biopolymer, is a major constituent of plant cell walls. Due to its chemical and structural complexity, lignin degradation is a challenging task for both natural and engineered systems. Therefore, investigation of lignin degradation using so called “model compounds” [...] Read more.
Lignin, a complex and abundant biopolymer, is a major constituent of plant cell walls. Due to its chemical and structural complexity, lignin degradation is a challenging task for both natural and engineered systems. Therefore, investigation of lignin degradation using so called “model compounds” has been the focus of many research efforts in recent years. This study addresses the utility of guaiacylglycerol-β-guaiacyl ether (Gβ2) as a model compound for evaluating the β-O-4 bond cleavage under diverse thermal and aqueous medium conditions. Experimental conditions included varied pH (3–10), microbial biodegradation, subcritical water environment (150–250 °C), and mild pyrolysis (150–250 °C). A high-performance liquid chromatography with high-resolution mass spectrometry was employed for accurate detection and quantification of both Gβ2 and its degradation/modification products in an aqueous environment. Pyrolysis experiments were performed using gas chromatography-mass spectrometry analysis with a pyrolyzer. The results showed that Gβ2 remained stable under exposure to moderate pH and several bacterial strains, which were successfully used previously for biodegradation of other recalcitrant pollutants. We report, for the first time, differing Gβ2 breakdown pathways for subcritical water treatment vs. pyrolysis under an inert atmosphere. The scientific novelty lies in the presentation of differences in the degradation pathways of Gβ2 during subcritical water treatment compared to pyrolysis in an inert atmosphere, with water playing a key role. The observed differences are ascribed to the suppression of homolytic reactions by water as a solvent. Full article
(This article belongs to the Topic Advances in Chemistry and Chemical Engineering)
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15 pages, 4669 KiB  
Article
Cross-Contamination of Ignitable Liquid Residues on Wildfire Debris—Effects of Packaging and Storage on Detection and Characterization
by Nadin Boegelsack, James Walker, Court D. Sandau, Dena W. McMartin, Jonathan M. Withey and Gwen O’Sullivan
Separations 2024, 11(2), 58; https://doi.org/10.3390/separations11020058 - 13 Feb 2024
Viewed by 1270
Abstract
Producing defensible data for legal proceedings requires strict monitoring of sample integrity. In fire debris analysis, various approved packaging and storage solutions are designed to achieve this by preventing cross-contamination. This study examines the efficiency of current practices at preventing cross-contamination in the [...] Read more.
Producing defensible data for legal proceedings requires strict monitoring of sample integrity. In fire debris analysis, various approved packaging and storage solutions are designed to achieve this by preventing cross-contamination. This study examines the efficiency of current practices at preventing cross-contamination in the presence of a sample matrix (charred wood) via analysis by comprehensive multidimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-ToF MS). The transfer of ignitable liquid residue (ILR) was assessed by comparing percentages of the target ILR area relative to the total chromatogram area and applying chemometric tools developed to detect cross-contamination. All practices reduced cross-contamination in comparison to faulty packaging. Individual practices varied in their performance. Nylon-based packaging performed best, whereas commercial polyethylene-based packaging performed worst due to interfering compounds emitted from the material and sealing mechanism. Heat-sealing was the best sealing mechanism when applied correctly, followed by press-fit connections, and lastly, adhesive sealing. Refrigerated storage offered several advantages, with elevated impact for polyethylene-based packaging and adhesive sealing mechanisms. Triple-layer packaging practices did not show significant benefits over double-layers. The recommended packaging approach based on these findings is mixed-material packaging (metal quart can in a heat-sealed nylon bag), offering advanced prevention of cross-contamination and practical advantages with continued refrigeration during transport. Full article
(This article belongs to the Section Forensics/Toxins)
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14 pages, 3078 KiB  
Article
Extraction of Phycocyanin and Chlorophyll from Spirulina by “Green Methods”
by Krastena Nikolova, Nadezhda Petkova, Dasha Mihaylova, Galia Gentscheva, Georgi Gavrailov, Ivaylo Pehlivanov and Velichka Andonova
Separations 2024, 11(2), 57; https://doi.org/10.3390/separations11020057 - 12 Feb 2024
Viewed by 1534
Abstract
Phycocyanin is a pigment–protein complex from the group of phycobiliproteins obtained from Spirulina (Arthrospira platensis), with possibilities for various applications in food and pharmaceutical technologies. It is a natural colorant for food and cosmetic products. This study aimed to investigate the effect [...] Read more.
Phycocyanin is a pigment–protein complex from the group of phycobiliproteins obtained from Spirulina (Arthrospira platensis), with possibilities for various applications in food and pharmaceutical technologies. It is a natural colorant for food and cosmetic products. This study aimed to investigate the effect of ultrasonic and microwave extraction conditions on antioxidant activity (AOA), chlorophyll content, and the content and purity index of phycocyanin in aqueous and alcoholic extracts of Spirulina (Arthrospira platensis). For this purpose, ultrasonic extraction with water or ethanol was performed at 20 °C, 30 °C, and 40 °C for 1, 2, and 3 h at an ultrasonic frequency of 36 kHz, 40 kHz, and 45 kHz. Microwave water extraction was performed for 60 s, 120 s, and 180 s. For each of the obtained samples, three parallel measurements of antioxidant activity were made by DPPH and FRAP methods, and chlorophyll content and phycocyanin yield and purity index were determined spectrophotometrically. Ultrasonic extraction resulted in a higher yield and purity index of phycocyanin compared to microwave extraction. The highest yield of 14.88 mg g−1 with a purity index of 1.60 was achieved at a temperature of 40 °C for one hour and an ultrasonic wave frequency of 40 kHz. A relatively low yield of 4.21 mg g−1, but with a purity index of 2.67, was obtained at a temperature of 30 °C, a time of two hours, and an ultrasonic frequency of 40 kHz. Chlorophyll b content at 20 °C, for two hours and ultrasonic frequency 40 kHz was 1.400 mg g−1. The study proposes ultrasonic extraction as a green method to obtain phycocyanin of varying purity index that may be used for food, cosmetic, or biomedical purposes. Full article
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17 pages, 4787 KiB  
Article
Spatially and Temporally Resolved Analysis of Bleeding in a Centrifugal Partition Chromatography Rotor
by Felix Buthmann, Philip Laby, Djamal Hamza, Jörg Koop and Gerhard Schembecker
Separations 2024, 11(2), 56; https://doi.org/10.3390/separations11020056 - 10 Feb 2024
Cited by 2 | Viewed by 1040
Abstract
Centrifugal Partition Chromatography (CPC) is a separation technique that utilizes immiscible liquid phases to purify compounds. The selection of solvents in Liquid–Liquid Chromatography offers flexibility and optimization possibilities for specific separation tasks. Understanding the hydrodynamics inside the apparatus is crucial for optimizing a [...] Read more.
Centrifugal Partition Chromatography (CPC) is a separation technique that utilizes immiscible liquid phases to purify compounds. The selection of solvents in Liquid–Liquid Chromatography offers flexibility and optimization possibilities for specific separation tasks. Understanding the hydrodynamics inside the apparatus is crucial for optimizing a CPC process. The phase retention ratio (Sf) determines the apparatus’s operating point and separation efficiency. However, stationary phase leakage, known as bleeding, complicates the immobilization of this phase. We used a partly transparent single-disc rotor to investigate the time and space dependency of bleeding inside a CPC apparatus, enabling real-time and localized determination of the phase retention ratio. By tracking the retention values over time, we observed the bleeding phenomenon and its progression from the inlet to the rotor outlet. Depending on the phase system used, the CPC was utilizable for a separation task for only 173–500 dimensionless residence times. Systems with a higher stability parameter (as described in the literature) showed a lower bleeding rate and increased stability over time. Accordingly, our results demonstrate the importance of maintaining an optimal ratio of mobile to stationary phase for efficient separation. Full article
(This article belongs to the Section Purification Technology)
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14 pages, 1692 KiB  
Article
Development and Validation of HPLC-FLD Analysis of Perampanel in MEPS-Processed Rat Plasma Sample
by Ayah Nader Abu-shark, Ashok K. Shakya, Safwan M. Al-Adwan and Rajashri R. Naik
Separations 2024, 11(2), 55; https://doi.org/10.3390/separations11020055 - 08 Feb 2024
Viewed by 970
Abstract
Perampanel, a novel α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, is registered for the adjunctive treatment of patients (aged ≥ 12 years) with refractory partial-onset seizures. A simple high-performance liquid chromatographic method fluorescence detection (HPLC-FLD) was developed to analyze perampanel in rats’ plasma and validated [...] Read more.
Perampanel, a novel α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, is registered for the adjunctive treatment of patients (aged ≥ 12 years) with refractory partial-onset seizures. A simple high-performance liquid chromatographic method fluorescence detection (HPLC-FLD) was developed to analyze perampanel in rats’ plasma and validated for bioanalytical purposes. Rats’ plasma (50 µL) was processed by microextraction packed sorbent (MEPS). The analytes were separated using a Hypersil Gold octadecyl silane column (250 × 4.6 mm internal diameter, 5 μm particle size) with isocratic elution. A mobile phase consisting of acetonitrile–methanol–water (275:275:450, v/v/v; containing 50 µL triethylamine and pH adjusted to 3.25 with orthophosphoric acid) was used in this analysis. The flow rate was 1.25 mL/min. Analytes were monitored at an excitation wavelength of 285 nm and an emission wavelength of 430 nm. The linearity range for this validated method was from 3.75 to 300 ng/mL. No endogenous peaks were found in the elution of analytes in drug-free rats’ plasma. Intra- and inter-batch reproducibility studies demonstrated accuracy and precision within the acceptance criteria. The results indicate that the present method is simple, selective, reproducible, and suitable for the analysis of perampanel in small volume samples. The robustness of the method was accessed using MODDE® design of experiments software version 12.5. Full article
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13 pages, 1676 KiB  
Article
A New Ultra High-Performance Liquid Chromatography-Tandem Mass Spectrometry Method to Monitor 1-Amino-4-Methyl-Piperazine and 1-Methyl-4-Nitroso-Piperazine in Rifampicin Hydrolysis: A Standard Addition Approach to Quantify Nitrosamine in Rifampicin
by Alessia Panusa, Paola Rotundo, Daniele Sadutto, Andrea Rodomonte and Roberto Cirilli
Separations 2024, 11(2), 54; https://doi.org/10.3390/separations11020054 - 07 Feb 2024
Viewed by 1209
Abstract
1-amino-4-methyl-piperazine (AMP) is both a starting material for the synthesis of rifampicin (RIF) and a degradation product of RIF hydrolysis. 1-methyl-4-nitroso-piperazine (MNP) is an oxidation product of AMP as well as a potentially genotoxic N-nitrosamine. The EMA and FDA have approved an ad [...] Read more.
1-amino-4-methyl-piperazine (AMP) is both a starting material for the synthesis of rifampicin (RIF) and a degradation product of RIF hydrolysis. 1-methyl-4-nitroso-piperazine (MNP) is an oxidation product of AMP as well as a potentially genotoxic N-nitrosamine. The EMA and FDA have approved an ad interim limit of 5 ppm for MNP in RIF drug products. As in-house methods for the analysis of MNP in RIF use a wide range of conditions for mobile phases and sample diluents, we decided to investigate whether these conditions affect the formation of MNP and AMP. A UHPLC-MS/MS method was developed to simultaneously quantify AMP and MNP during RIF hydrolysis in buffered aqueous solutions at different pH levels. Analyses were performed in MRM mode; separations were carried out on an InfinityLab Poroshell HPH-C18 (100 mm, 2.1 mm i.d., particle size 1.9 μm). In aqueous RIF solutions, the content of AMP and MNP increases with time; at different pHs, the concentration of AMP increases much faster in acidic than in basic solutions; and the increase in MNP can be reduced by the addition of ascorbic acid. To avoid an overestimation of MNP, water should not be used as a diluent in RIF sample preparations. Methanol is a more suitable diluent than water. A standard addition method has been validated for the quantification of MNP in RIF drug substances. Full article
(This article belongs to the Section Chromatographic Separations)
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16 pages, 3745 KiB  
Article
Analysis of the Lipid Component and the Sterol Ester Fraction for the Detection of Soft Wheat in Durum Wheat Flour and Pasta
by Daniele Naviglio, Angela Perrone, Francesca Varchetta, Paolo Trucillo, Domenico Montesano and Monica Gallo
Separations 2024, 11(2), 53; https://doi.org/10.3390/separations11020053 - 07 Feb 2024
Viewed by 1074
Abstract
Food adulteration consists of changing the original structure of a food, and so, by its definition, it is a process not admitted by law. Adulterations can not only have commercial consequences, but also hygienic and nutritional ones, and in some cases, they can [...] Read more.
Food adulteration consists of changing the original structure of a food, and so, by its definition, it is a process not admitted by law. Adulterations can not only have commercial consequences, but also hygienic and nutritional ones, and in some cases, they can cause a serious danger to public health. Therefore, it is of great interest to understand and identify the modifications that alter the original chemical composition of a food item (nutrition label). Among the food processing sectors, the pasta food chain is a fascinating production process, which finds its roots in a mixture of a few, simple ingredients; in particular, in its basic formulation to produce pasta, exclusively durum wheat mixed with water is used, while soft wheat and therefore the flour obtained from it are destined for bakeries and the confectionery industry. In this work, a procedure was developed that allows the detection of the possible presence of soft wheat in durum wheat-based products, both in the flour and after the pasta-making process. It is to point out that this adulteration is only commercial fraud and there are no consequences for people’s health. In detail, the method was based on the isolation of the lipid fraction of flours and pastas and using the gas chromatographic analysis of the sterol ester fraction, which were not altered during the pasta-making phase, because they have very high boiling points. Based on the evaluation of some specific ratios between sterol esters, it was possible to trace the percentage of soft wheat present in a mixture with durum wheat, both in flour products and pastas. Full article
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14 pages, 3564 KiB  
Article
Content of Acidic Compounds in the Bean of Coffea arabica L., Produced in the Department of Cesar (Colombia), and Its Relationship with the Sensorial Attribute of Acidity
by Luz Fanny Echeverri-Giraldo, Valentina Osorio Pérez, Claudia Tabares Arboleda, Lady Juliet Vargas Gutiérrez and Luis Carlos Imbachi Quinchua
Separations 2024, 11(2), 52; https://doi.org/10.3390/separations11020052 - 07 Feb 2024
Viewed by 1087
Abstract
Cesar, a coffee-growing department in Colombia, has particular characteristics that favor the production of coffees differentiated by sensory profile, for which the acidity attribute stands out. The chemical composition and sensory quality of the coffee produced by 160 coffee growers during two production [...] Read more.
Cesar, a coffee-growing department in Colombia, has particular characteristics that favor the production of coffees differentiated by sensory profile, for which the acidity attribute stands out. The chemical composition and sensory quality of the coffee produced by 160 coffee growers during two production harvests (2021 and 2022) and processed by the wet method were evaluated to correlate the contents of the main acidic chemical compounds present in green coffee beans with the perceived acidity of the beverage. The chemical analysis of coffee samples utilized spectrophotometric methods and HPLC-DAD techniques. Lactic, 3,5-di-CQA and phosphoric acids were good discriminators of acidity classified as excellent; that is, with a score higher than 7.75 on the Specialty Coffee Association (SCA) scale, presenting the highest contents in the green coffee bean. There was a direct linear relationship between acidity and 3,5-di-CQA and 5-CQA and an inverse relationship between acidity and 3-CQA, 4-CQA and 4,5-CQA. These findings contribute to the understanding of the quality and chemistry of Colombian coffee. Full article
(This article belongs to the Special Issue Bioactive Compounds in Foods: Separation, Extraction and Application)
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15 pages, 2158 KiB  
Article
Determination of Topiramate and Carbamazepine in Plasma by Combined Dispersive Liquid–Liquid Microextraction and Gas Chromatography–Mass Spectrometry
by Pamela Cabarcos-Fernández, María Jesús Tabernero-Duque, Iván Álvarez-Freire and Ana María Bermejo-Barrera
Separations 2024, 11(2), 51; https://doi.org/10.3390/separations11020051 - 07 Feb 2024
Viewed by 994
Abstract
Dispersive liquid–liquid microextraction, an environmentally friendly extraction technique, followed by gas chromatography–mass spectrometry operating in selected ion monitoring (SIM) mode, is here presented for the simultaneous determination of two anticonvulsant drugs in plasma, Topiramate and Carbamazepine. Experimental parameters affecting the recovery of the [...] Read more.
Dispersive liquid–liquid microextraction, an environmentally friendly extraction technique, followed by gas chromatography–mass spectrometry operating in selected ion monitoring (SIM) mode, is here presented for the simultaneous determination of two anticonvulsant drugs in plasma, Topiramate and Carbamazepine. Experimental parameters affecting the recovery of the proposed extraction method, such as the extraction and dispersion solvent, the extraction and dispersion volume, the sample amount, the pH of the aqueous phase, the ultrasound time, the centrifugation time and ionic strength, were investigated. The limits of detection for Topiramate and Carbamazepine were 0.01 and 0.025 µg mL−1, and the limits of quantification were 0.025 µg mL−1 and 0.05 µg mL−1, respectively. The method is shown to be selective, accurate, precise and linear over the concentration ranges of 0.025–8 µg mL−1 for Topiramate and 0.05–3 µg mL−1 for Carbamazepine. The extraction recovery of the analytes ranged from 91.5% to 113.9%. The analytical method was successfully applied to real plasma samples received by the Forensic Toxicology Service of the Forensic Science Institute of Santiago de Compostela. Full article
(This article belongs to the Section Chromatographic Separations)
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23 pages, 5556 KiB  
Article
Exploring Bioactive Phytochemicals in Gymnema sylvestre: Biomedical Uses and Computational Investigations
by Uday M. Muddapur, Samiksha Manjunath, Yahya S. Alqahtani, Ibrahim Ahmed Shaikh, Aejaz Abdullatif Khan, Basheerahmed Abdulaziz Mannasaheb, Deepak Yaraguppi and Sunil S. More
Separations 2024, 11(2), 50; https://doi.org/10.3390/separations11020050 - 06 Feb 2024
Viewed by 1338
Abstract
The main objective of this research was to perform Gymnema sylvestre (Asclepiadaceae) extract’s phytochemical screening and identify its therapeutic potential. Using a Soxhlet apparatus, the powdered plant material was extracted using ethyl acetate. The preliminary phytochemical analysis confirmed the presence of alkaloids, flavonoids, [...] Read more.
The main objective of this research was to perform Gymnema sylvestre (Asclepiadaceae) extract’s phytochemical screening and identify its therapeutic potential. Using a Soxhlet apparatus, the powdered plant material was extracted using ethyl acetate. The preliminary phytochemical analysis confirmed the presence of alkaloids, flavonoids, phenols, glycosides, and steroids. Gas chromatography–mass spectroscopy analysis of the extract was performed and confirmed the presence of 11 compounds. As per the quantitative analysis, the extract exhibited a phenolic content of 948 µg gallic acid equivalent/g dry weight, a total flavonoid content of 398 µg quercetin equivalent/g dry weight, and an alkaloid content of 487 µg atropine equivalent/g dry weight. As per the in vitro cytotoxicity test using A549 cells, the IC50 (half-maximal inhibitory concentration) value for the extract was found to be 76.06 ± 1.26 µg/mL, indicating its cytotoxic effect on the cells. The ethyl acetate extract showed significant antibacterial efficacy, as evidenced by a zone of clearance measuring 3 mm against Escherichia coli and 6 mm against Bacillus subtilis. For anthelmintic activity, the earthworm paralysis time induced by G. sylvestre extract (10 mg/mL) was 28.13 ± 0.8 min, and the time of death was 68.21 ± 1.72 min. In comparison, the reference drug, piperazine citrate (10 mg/mL), caused paralysis in 22.18 ± 1.02 min and resulted in death at 66.22 ± 2.35 min. Similarly, the coagulation time was notably prolonged, with blood clot formation observed at 1 min and 40 s, at a concentration of 1 mg/mL, which underscores the potential anticoagulant or hemostatic modulation properties of G. sylvestre extract. The test extract showed good inhibition of alpha-amylase activity and exhibited an IC50 value of 15.59 µg/mL. The IC50 value for DPPH (2,2-diphenyl-1-picrylhydrazyl)-scavenging activity for the extract was 19.19 µg/mL. Based on the GCMS results, the compound 2,7-dimethyl-undecane was selected for its anticancer potential. Docking studies were conducted with the epidermal growth factor receptor (EGFR) protein, specifically the 5WB7 variant associated with lung cancer. The docking score was −4.5, indicating a potential interaction. Key interaction residues such as ASN328, VAL350, and THR358 were identified. Overall, this research provides valuable insights into the phytochemical composition and diverse biological activities of G. sylvestre extract, offering a foundation for further exploration of its medicinal and pharmacological potential. Full article
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13 pages, 1653 KiB  
Article
Chemical Composition and Antistaphylococcal Activity of Essential Oil of Curcuma mangga Rhizome from Indonesia
by Klara Urbanova, Andreas Romulo, Marketa Houdkova, Pavel Novy and Ladislav Kokoska
Separations 2024, 11(2), 49; https://doi.org/10.3390/separations11020049 - 06 Feb 2024
Viewed by 1079
Abstract
This study assessed the antistaphylococcal activity of essential oil (EO) hydrodistilled from the rhizome of Curcuma mangga grown in Indonesia using the broth microdilution volatilization method and standard broth microdilution method modified for evaluation of volatile agents, as well as described its chemical [...] Read more.
This study assessed the antistaphylococcal activity of essential oil (EO) hydrodistilled from the rhizome of Curcuma mangga grown in Indonesia using the broth microdilution volatilization method and standard broth microdilution method modified for evaluation of volatile agents, as well as described its chemical composition using gas chromatography (GC) with mass spectrometry (MS). A fused-silica HP-5MS column and a DB-17MS column were used to separate the components into two columns. The results demonstrated that the EO exhibited antistaphylococcal activity at the minimum inhibitory concentration (MIC) ranging from 128 to 1024 µg/mL. In contrast, the clinical isolate of tetracycline-resistant Staphylococcus aureus was the most sensitive strain (MIC 128 µg/mL). The major constituents of the EO were 15,16-dinorlabda-8(17),11-dien-13-one (24.63/15.78%), followed by ambrial (16.12/10.97%), 13-nor-eremophil-1(10)-en-11-one (7.16/6.21%), 15,16-dinorlabda-8(17),12-dien-14-al (6.61/11.57%), and aromadendrene oxide (5.98/3.77%). These results propose C. mangga rhizome EO as a promising agent for developing natural-based anti-infective preparations. Full article
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10 pages, 3379 KiB  
Communication
CO2 Adsorption by Bamboo Biochars Obtained via a Salt-Assisted Pyrolysis Route
by Xing Xie, Mangmang Li, Dan Lin, Bin Li, Chaoen Li and Dongjing Liu
Separations 2024, 11(2), 48; https://doi.org/10.3390/separations11020048 - 06 Feb 2024
Viewed by 1070
Abstract
Recently, salt-assisted pyrolyzation has been deemed an emerging and efficient method for the preparation of biochars due to its facile operation as well as its good structural and chemical properties. In this work, biochars (MBCx) are prepared by heating bamboo powders [...] Read more.
Recently, salt-assisted pyrolyzation has been deemed an emerging and efficient method for the preparation of biochars due to its facile operation as well as its good structural and chemical properties. In this work, biochars (MBCx) are prepared by heating bamboo powders in eutectic salts (Li2CO3 + K2CO3) at 500–600 °C in the air. Multiple technologies are employed to examine the physiochemical properties of bamboo biochars. Correlations between heating temperature and structural features and carbon dioxide uptakes of bamboo biochars have been investigated. The results show that heating temperature has a significant influence on the physicochemical properties of bamboo biochars. With the elevation of the heating temperature, the defect structures of bamboo biochars gradually ascend, especially when the heating temperature reaches 600 °C. MBCx biochars visibly exceed conventional bamboo biochar prepared via pyrolyzation in a nitrogen stream free of salt addition. Pyrolysis of bamboo in eutectic salts endows biochars with higher oxygen content and more carbon defects, which likely accounts for their better CO2 capture activities. Full article
(This article belongs to the Special Issue Functional Materials for CO2 and Hg0 Removal)
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15 pages, 16528 KiB  
Article
Risk Characterization of Botanical Extracts Containing Hydroxyanthracenes as Determined by a Validated Micronucleus In Vitro Assay
by Gloria Melzi, Corrado L. Galli and Marina Marinovich
Separations 2024, 11(2), 47; https://doi.org/10.3390/separations11020047 - 06 Feb 2024
Viewed by 1121
Abstract
Extracts of Rheum palmatum L., Rhamnus purshiana DC., Rhamnus frangula L., and Cassia senna L. are used in traditional medicine thanks to their beneficial properties. These species contain hydroxyanthracene derivatives, considered genotoxic and possibly related to colorectal cancer development. This research aimed to [...] Read more.
Extracts of Rheum palmatum L., Rhamnus purshiana DC., Rhamnus frangula L., and Cassia senna L. are used in traditional medicine thanks to their beneficial properties. These species contain hydroxyanthracene derivatives, considered genotoxic and possibly related to colorectal cancer development. This research aimed to study, using a micronucleus assay in vitro, the genotoxic potential of Rheum palmatum L., Rhamnus purshiana DC., Rhamnus frangula L. (bark), and Cassia senna L. (leaves and fruits) extracts. The extracts were evaluated at different concentrations: from 0 to 2000 µg/mL for Rhamnus purshiana DC, from 0 to 2500 µg/mL for Rheum palmatum L. and Rhamnus frangula L., and from 0 to 5000 µg/mL for Cassia senna L. The cytokinesis-block proliferation index was calculated to analyse if the used concentrations showed cytotoxicity. The hydroxyanthracene content varied between 0.06% and 0.23% for aloe-emodin, and between 0.07% and 0.16% for emodin and rhein. No cytotoxic effect was detected at any of these concentrations. Micronucleus analyses showed a lack of genotoxicity for all the extracts tested. These results show that Rheum palmatum L., Rhamnus purshiana DC, Rhamnus frangula L., and Cassia senna L. extracts do not induce genotoxicity since no increase in micronuclei formation in human lymphocytes in vitro was detected. Full article
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25 pages, 3820 KiB  
Article
The Impact of Pesticide Residues on Soil Health for Sustainable Vegetable Production in Arid Areas
by Turki Kh. Faraj, Mohamed Hamza EL-Saeid, Mohamed M. M. Najim and Maha Chieb
Separations 2024, 11(2), 46; https://doi.org/10.3390/separations11020046 - 31 Jan 2024
Viewed by 1246
Abstract
The assessment of pesticide residues in agricultural soils is an essential prerogative in maintaining environmental health standards. Intensive vegetable cultivation is practiced in the Al-Kharj area of the eastern Najd region of Saudi Arabia, where excessive applications of agrochemicals are reported to pollute [...] Read more.
The assessment of pesticide residues in agricultural soils is an essential prerogative in maintaining environmental health standards. Intensive vegetable cultivation is practiced in the Al-Kharj area of the eastern Najd region of Saudi Arabia, where excessive applications of agrochemicals are reported to pollute vegetable-growing soils, challenging the sustainable management of soils and groundwater resources. This study aimed to monitor the levels of thirty-two types of pesticide residues in the soils of vegetable fields and the estimated potential health risk for humans due to non-dietary exposure to pesticides in soils in the Al-Kharj region. Pesticide residues were evaluated at 0–10 cm and 10–20 cm depths at 20 sampling sites from Al-Kharj. Gas chromatograph-mass spectrometry, coupled with a quadrupole mass spectrometer with a GC column, was used in the analysis. The results indicated that agrochemical residues show prolonged soil pollution that may cause adverse impacts on human and environment. Herbicides Atrazine, Isoproturpon, and Linuron have been detected in the soils, and these pose many problematic environmental threats. Bromoxynil, Pendimetholin, and Diclofop-methyl could be used as per the recommendations to sustainably manage soil and water resources in the Al-Kharj area. Resmethrin, Methidathion, Ethoprophos, Tetramethrin, Bromophis-methyl, Bifenthion, Permethrin, Fenoxycarb, Cyfluthrin, Phosmet, and Azinophos-methyl can be used safely in the Al-Kharj agricultural area, maintaining sustainable soils and water resources. Applications of Carbaryl require sufficient care, while Endosulfan, Deltamethrin, Lindane, Chlorpyrifos, Chlorpyrifos-methly, Dimethoate, Heptachlor, and Mevinphos, which are detected in soils, require policy guidelines to limit the use to ensure sustainability. Policy interventions need to be formulated to increase the sustainability of soil management and groundwater resources in the Al-Kharj region to ensure the safety of people who are in direct contact with the agrochemicals used and to ensure the safety of agricultural products generated in this region. Full article
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16 pages, 2032 KiB  
Article
HILIC Separation Methods on Poly-Hydroxyl Stationary Phases for Determination of Common Saccharides with Evaporative Light-Scattering Detector and Rapid Determination of Isomaltulose in Protein-Rich Food Supplements
by Tomáš Crha, Grace F. Odedina and Jiří Pazourek
Separations 2024, 11(2), 45; https://doi.org/10.3390/separations11020045 - 30 Jan 2024
Viewed by 1123
Abstract
This article highlights the fundamental aspects of hydrophilic interaction liquid chromatography (HILIC) on poly-hydroxyl stationary phases to analyze non-derivatized mono- and disaccharides, including commonly consumed carbohydrates like glucose, fructose, sucrose, and lactose. The evaporative light-scattering detector (ELSD) is utilized as an alternative to [...] Read more.
This article highlights the fundamental aspects of hydrophilic interaction liquid chromatography (HILIC) on poly-hydroxyl stationary phases to analyze non-derivatized mono- and disaccharides, including commonly consumed carbohydrates like glucose, fructose, sucrose, and lactose. The evaporative light-scattering detector (ELSD) is utilized as an alternative to an MS detector, and the separation system’s selectivity allows the separation of anomers of monosaccharides. The study also includes a rapid method for determining isomaltulose (Palatinose), which was validated and applied to food supplement samples available in the Czech market, even those with high protein content. Additionally, isomaltulose was separated from sucrose in just 13 min. Full article
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16 pages, 1989 KiB  
Article
Phytochemical Content and Anticancer Activity of Jamaican Dioscorea alata cv. White Yam Extracts
by Kenroy Wallace, Racquel Wright, Melisa Williams-Longmore, Sasha-Gay Wright and Helen Asemota
Separations 2024, 11(2), 44; https://doi.org/10.3390/separations11020044 - 30 Jan 2024
Viewed by 1411
Abstract
Dioscorea spp. is known for its myriad medicinal properties. D. alata, specifically crude extracts, have displayed potent anticancer properties. However, the chemical constituents of these extracts have not been examined. The aim of this study is to determine the chemical composition and [...] Read more.
Dioscorea spp. is known for its myriad medicinal properties. D. alata, specifically crude extracts, have displayed potent anticancer properties. However, the chemical constituents of these extracts have not been examined. The aim of this study is to determine the chemical composition and antioxidant characteristics of the active extracts from D. alata tuber. Chemoinformatic profiling of the Jamaican Dioscorea alata cultivar white yam tuber was generated by a sequential Soxhlet extraction of dried milled tuber, producing five crude extracts: hexane (E-1), diethyl ether (E-2), acetone (E-3), ethanol (E-4) and water (E-5). The analytes within the five extracts were dissolved in 0.1% DMSO and their anticancer activity was determined using DU145 prostate cancer cells. Both the acetone and the ethanolic extract were able to induce greater than 50% cell death at 50 µg/mL. The order of growth inhibition of the extracts in DU-145 cell is E3 (IC50, 10.81 µg/mL) > E-4 (IC50 24.17 µg/mL) > E-1 (IC50 > 100 µg/mL) ≥ E-2 (IC50 > 100 µg/mL) ≥ E-5 (IC50 > 100 µg/mL). Phytochemical screening of both E-3 and E-4 revealed the presence of all major classes of secondary metabolites except tannins. Resins were also absent in the E-3 extract. Phenolic quantification indicated that E-3 and E-4 possessed GAEs of 31 ± 1.1 and 72 ± 1.8 mg per g of sample, respectively. Inversely, E-3 displayed greater antioxidant capability with IC50 of 82.9 µg/mL compared to E-4 (166.9 µg/mL); however, neither was comparable to citric acid (33.6 µg/mL). The extract E-3 was further isolated by HPLC into 11 fractions. Fractions 4 and 5 possessed potent cell growth inhibitory effects. GCMs of fractions 4 and 5 showed they possessed numerous saturated fatty acids with pharmacological relevance. The presence of these compounds shows potential for exploitation of D. alata extracts for pharmacological purposes. Full article
(This article belongs to the Special Issue Advances in Chromatographic Analysis of Bioactive Compounds)
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12 pages, 749 KiB  
Article
Development and Validation of an HPLC-DAD Method for the Determination of Seven Antioxidants in a Nano-Emulsion: Formulation and Stability Study
by Georgios Kamaris, Antonia Dalavitsou and Catherine K. Markopoulou
Separations 2024, 11(2), 43; https://doi.org/10.3390/separations11020043 - 29 Jan 2024
Viewed by 1492
Abstract
Oxidative stress degrades skin collagen and elastin and causes inflammatory reactions that affect mitochondrial DNA leading to aging. In the present study, a potential cosmetic nano-emulsion (o/w) of seven substances (chlorogenic acid, caffeine, rutin, hesperidin, quercetin, α-tocopherol and retinol) with antioxidant and anti-aging [...] Read more.
Oxidative stress degrades skin collagen and elastin and causes inflammatory reactions that affect mitochondrial DNA leading to aging. In the present study, a potential cosmetic nano-emulsion (o/w) of seven substances (chlorogenic acid, caffeine, rutin, hesperidin, quercetin, α-tocopherol and retinol) with antioxidant and anti-aging properties was prepared and analyzed. The lipophilic components were entrapped in the dispersed nanoparticles (jojoba) of the emulsion while the hydrophilic ones dissolved in the aqueous phase (glycerol/water). Suitable excipients were selected using an experimental design methodology with two mixtures and two responses (particle size and zeta potential). The quantitative extraction of chlorogenic acid and caffeine from Crithmum maritimum L. plant and coffee beans (Coffea arabica L.) and their stability were also studied. The analysis of the substances was carried out on an HPLC-DAD, with a phenyl column and gradient elution system (solvent A: water with 0.2% formic acid and B: acetonitrile with 0.2% formic acid). Validation of the method was performed in terms of linearity (r2 > 0.998), precision and repeatability (%RSD < 2) while the limits of detection (LLODs) and quantification (LLOQs) were also determined. The antioxidants were quantified after being extracted from the substrate (%recovery 96.7–102.5, %RSD < 2). Full article
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12 pages, 1198 KiB  
Article
Determination of Perfluorinated and Polyfluorinated Alkyl Substances (PFASs) in PM10 Samples: Analytical Method, Seasonal Trends, and Implications for Urban Air Quality in the City of Terni (Central Italy)
by Simone Moretti, Silvia Castellini, Carolina Barola, Elisabetta Bucaletti, Chiara Petroselli, Roberta Selvaggi, Mara Galletti, David Cappelletti and Roberta Galarini
Separations 2024, 11(2), 42; https://doi.org/10.3390/separations11020042 - 28 Jan 2024
Viewed by 1348
Abstract
A quantitative analytical method for PFAS determination in airborne particulate matter (PM) has been developed using liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS), allowing for the determination of 33 compounds. The procedure was applied to ambient PM10 with limits of quantification [...] Read more.
A quantitative analytical method for PFAS determination in airborne particulate matter (PM) has been developed using liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS), allowing for the determination of 33 compounds. The procedure was applied to ambient PM10 with limits of quantification for PFAS in the fg m−3 range. PM10 samples collected during a year-long campaign conducted in an urban site in Umbria (Central Italy) have been characterized for their PFAS content. Among the seven detected PFASs, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) were the most abundant compounds. Furthermore, this work allowed us to obtain the first seasonal trend of airborne PFASs in Central Italy. Seasonal trend analysis shows that PFAS concentration in the atmosphere peaks in summertime. A comparison with trends of other relevant primary and secondary air pollutants determined at the sampling site suggests a secondary nature of the observed PFAS, which are formed in the atmosphere directly from gaseous precursors and can contribute to worsen the urban air quality in summertime. Full article
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12 pages, 647 KiB  
Article
An LC-MS/MS Method for the Simultaneous Quantification of Insulin, Cortisol, Glucagon-like Peptide 1, Ghrelin, and Osteocalcin
by Zhichao Zhang, Hareem Siddiqi, Yu-Ping Huang, Shannon McClorry, Peng Ji, Daniela Barile and Carolyn M. Slupsky
Separations 2024, 11(2), 41; https://doi.org/10.3390/separations11020041 - 27 Jan 2024
Viewed by 1325
Abstract
Hormones are important signaling molecules controlling physiological homeostasis. ELISA kits are commonly used to measure hormones; however, few ELISA kits are multiplex, not all species-specific ELISA kits are commercially available, and ELISA kits typically require a significant volume of biological fluids. Pigs resemble [...] Read more.
Hormones are important signaling molecules controlling physiological homeostasis. ELISA kits are commonly used to measure hormones; however, few ELISA kits are multiplex, not all species-specific ELISA kits are commercially available, and ELISA kits typically require a significant volume of biological fluids. Pigs resemble humans in digestive physiology, making them an excellent model in preclinical research of nutrition and metabolism. In this study, we developed and validated a simple liquid–liquid extraction procedure and LC-MS/MS method for the simultaneous quantification of insulin, cortisol, glucagon-like peptide-1 (GLP-1) (7-37) and (7-36), acyl and des-acyl ghrelin, and carboxylated osteocalcin in pig serum. The proposed method is specific, highly sensitive (LOQ in ng/mL and pg/mL), reasonably accurate (more than 76.2% of all quality control samples within 20% error from nominal values), and precise (intra-day CV ≤ 10% and inter-day CV ≤ 23.1%). The recoveries of all analytes and corresponding internal standards ranged from 83.7 to 116.0%. The method also requires a low serum volume of 50–100 μL, which is invaluable when sample volume is limited. These methods could be easily extended for use in other mammalian species. Full article
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18 pages, 7788 KiB  
Article
Preparation and NH4+ Adsorption Performance of Ultrafine Lignite-Based Porous Materials
by Siyuan Zhang, Yuping Fan, Xianshu Dong, Xiaomin Ma, Maoqing Yang and Wei Xiao
Separations 2024, 11(2), 40; https://doi.org/10.3390/separations11020040 - 27 Jan 2024
Viewed by 1135
Abstract
This study aimed to increase the ammonium nitrogen adsorption capacity of lignite using ultrafine grinding, aiming to reduce eutrophication in water bodies. Ammonium sulfate (NH4)2SO4 was employed as a stand-in for ammonium nitrogen in water solutions. The lignite [...] Read more.
This study aimed to increase the ammonium nitrogen adsorption capacity of lignite using ultrafine grinding, aiming to reduce eutrophication in water bodies. Ammonium sulfate (NH4)2SO4 was employed as a stand-in for ammonium nitrogen in water solutions. The lignite sample for adsorption was processed with varying milling times. Adsorption efficacy was assessed primarily through isothermal adsorption tests and other techniques. Additionally, the study delved into the adsorption mechanisms. The results demonstrate that lignite ground for 50 min follows monolayer adsorption, characterized by minimal pore size and reduced diffusion rates, thereby extending the time to reach equilibrium and maximizing adsorption. BET and SEM analyses show that coal powder is effectively ground by zirconia balls in a vertical stirring mill, diminishing its particle size and forming new micropores. Concurrently, larger native pores are transformed into mesopores and micropores, providing numerous sites for NH4+ adsorption. XPS and FTIR analyses indicate an increase in exposed carbonaceous surfaces and oxygen-containing functional groups in ultrafine lignite. Ammonium ions replace hydrogen in carboxyl groups to form COONH4, and hydrogen bonds may form between NH4+ and C-O groups. Additionally, the electrostatic attraction between NH4+ and the coal surface further enhances adsorption. It can be concluded that the physical grinding process increases the specific surface area and creates more active adsorption sites, which in turn, boosts NH4+ adsorption capacity. The maximum equilibrium adsorption capacity is as high as 550 mg/g. This study suggests that ultrafine lignite is a promising material for treating ammonia-nitrogen wastewater. Full article
(This article belongs to the Special Issue Separation and Extraction Technology in Mineral Processing)
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15 pages, 4833 KiB  
Article
A Hydrothermal Synthesis Process of ZSM-5 Zeolite for VOCs Adsorption Using Desilication Solution
by Zhenhua Sun, Qingxiang Shu, Qikun Zhang, Shaopeng Li, Ganyu Zhu, Chenye Wang, Jianbo Zhang, Huiquan Li and Zhaohui Huang
Separations 2024, 11(2), 39; https://doi.org/10.3390/separations11020039 - 26 Jan 2024
Viewed by 1292
Abstract
ZSM-5 zeolite is a kind of high-value-added porous aluminosilicate zeolite. The use of the coal gasification slag utilization process by-product desilication liquid as a silicon raw material to replace the current raw materials such as water glass will help reduce production costs and [...] Read more.
ZSM-5 zeolite is a kind of high-value-added porous aluminosilicate zeolite. The use of the coal gasification slag utilization process by-product desilication liquid as a silicon raw material to replace the current raw materials such as water glass will help reduce production costs and achieve high-value utilization of solid waste. ZSM-5 zeolites for volatile organic compounds (VOCs) adsorption were prepared by a one-step hydrothermal method using the desilication solution prepared from coal gasification slag as the main silicon source and sodium source. The effects of crystallization reaction time, the crystallization temperature, the Na2O/SiO2 molar ratio, and the SiO2/Al2O3 molar ratio on the relative crystallinity and the specific surface area of the ZSM-5 zeolite were investigated and optimized. The optical reaction conditions were as follows: a crystallization time of 12 h, a crystallization temperature of 170 °C, a Na2O/SiO2 molar ratio of 0.2, and a SiO2/Al2O3 molar ratio of 200. The optimal ZSM-5 zeolite synthesized is hexagonal, with regular grains, a relative crystallinity of 101.48%, a specific surface area of 337.48 m2·g−1, and a pore volume of 0.190 cm3·g−1. And the optimal ZSM-5 zeolite was composed of SiO2 content of 97.52 wt%, Al2O3 content of 1.58 wt%, Na2O content of 0.33 wt%, and SiO2/Al2O3 molar ratio of 104.93. Na2O/SiO2 molar ratio is 0.0033. The results of static adsorption experiments show that the static adsorption capacities of ZSM-5 zeolite for p-xylene, benzene, toluene, and butyl acetate were 118.85, 69.98, 68.74, and 95.85 mg·g−1, respectively, which can effectively adsorb VOCs. The synthetic process of the ZSM-5 zeolite is a simple preparation process and short in synthesis time. The results of this study not only help to realize the high-value utilization of silicon components in solid waste, but also provide an economical and effective way to synthesize VOCs adsorption materials. Full article
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18 pages, 1766 KiB  
Article
HPLC and SFC Enantioseparation of (±)-Trans-β-Lactam Ureas on Immobilized Polysaccharide-Based Chiral Stationary Phases—The Introduction of Dimethyl Carbonate as an Organic Modifier in SFC
by Mladenka Jurin, Darko Kontrec and Marin Roje
Separations 2024, 11(2), 38; https://doi.org/10.3390/separations11020038 - 25 Jan 2024
Viewed by 1119
Abstract
A series of nine racemic trans-β-lactam ureas were analyzed for enantiomer separation by high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC). The separations were performed on three immobilized polysaccharide-based chiral analytical columns (CHIRAL ART Amylose-SA, CHIRAL ART Cellulose-SB and CHIRAL ART [...] Read more.
A series of nine racemic trans-β-lactam ureas were analyzed for enantiomer separation by high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC). The separations were performed on three immobilized polysaccharide-based chiral analytical columns (CHIRAL ART Amylose-SA, CHIRAL ART Cellulose-SB and CHIRAL ART Cellulose-SC). In HPLC mode, a normal-phase consisting of n-hexane/2-PrOH (90/10, v/v), a polar organic mobile phase consisting of 100% MeOH or 100% EtOH, and a non-standard mobile phase consisting of 100% dimethyl carbonate (DMC) were investigated. In SFC mode, the mobile phases CO2/alcohol (80/20, v/v) and CO2/DMC/alcohol (MeOH or EtOH; 70/24/6, v/v/v or 60/32/8, v/v/v) were investigated. The best achieved enantioseparation of trans-β-lactam ureas was obtained with an Amylose-SA column. We have shown that the green solvent dimethyl carbonate (DMC) can be efficiently used as a mobile phase in HPLC mode as well as in SFC mode along with the addition of polar organic modifiers (MeOH or EtOH). Full article
(This article belongs to the Special Issue Advances in Chromatographic Analysis of Bioactive Compounds)
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14 pages, 1674 KiB  
Article
The Simulation and Optimization of the Tetrafluoroethylene Rectification Process
by Limin Yang, Yue Chen, Jinzhi Wang, Yongzhen Luo, Pengfei Zhou and Xiaolai Zhang
Separations 2024, 11(2), 37; https://doi.org/10.3390/separations11020037 - 25 Jan 2024
Viewed by 1342
Abstract
In the R22 (chlorodifuoromethane) steam-cracking process, which is used to produce a TFE (tetrafluoroethylene) monomer, distillation is employed to separate the high-purity TFE monomer from the cracked gas generated during this procedure. Traditionally, this distillation process is carried out using five towers. In [...] Read more.
In the R22 (chlorodifuoromethane) steam-cracking process, which is used to produce a TFE (tetrafluoroethylene) monomer, distillation is employed to separate the high-purity TFE monomer from the cracked gas generated during this procedure. Traditionally, this distillation process is carried out using five towers. In this study, the traditional five-tower distillation method was transformed into a four-tower distillation method through the Aspen Plus simulation software, and this process was simulated and optimized. Meanwhile, a double-effect distillation process was designed for the transformed four-tower distillation process. The transformed distillation process not only meets the requirements of 99.999% purity for the TFE monomer and 99.99% purity for R22 recycling, but it also reduces the footprint by eliminating one distillation tower and saves 112.9002 kW of tower load, thus reducing the operating costs. This research provides valuable guidance for practical production. Full article
(This article belongs to the Topic Advances in Chemistry and Chemical Engineering)
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