Editor’s Choice Articles

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

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Article
A New Method for the Determination of Amisulpride in a Small Volume (200 μL) of Human Saliva Using LC-DAD Supported by SPE
Separations 2023, 10(5), 277; https://doi.org/10.3390/separations10050277 - 25 Apr 2023
Cited by 1 | Viewed by 735
Abstract
(1) Background: The concentration of amisulpride, an atypical antipsychotic drug, is most often determined in the blood, with many inconveniences. An alternative may be to use saliva as a diagnostic material for this purpose. The development of a method to determine amisulpride in [...] Read more.
(1) Background: The concentration of amisulpride, an atypical antipsychotic drug, is most often determined in the blood, with many inconveniences. An alternative may be to use saliva as a diagnostic material for this purpose. The development of a method to determine amisulpride in saliva using a small volume of biological material could significantly improve patient comfort during Therapeutic Drug Monitoring (TDM). (2) Methods: Therefore, the aim of this study was to develop a method to determine amisulpride in 200 μL of saliva using solid-phase extraction for isolation and liquid chromatography with a diode array detector (LC-DAD) for quantitative analysis. (3) Results: The method was validated by determining its linearity in the concentration range 5–500 ng/mL (R2 > 0.99), and the intra- and inter-day precision expressed as coefficient of variation (CV%) did not exceed 9%. (4) Conclusions: The developed method was used to determine the salivary concentration of amisulpride in patients treated with the studied compound, confirming its usefulness in TDM. Full article
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Article
Phenolic Profile of Castanea Bee Pollen from the Northwest of the Iberian Peninsula
Separations 2023, 10(4), 270; https://doi.org/10.3390/separations10040270 - 21 Apr 2023
Cited by 2 | Viewed by 865
Abstract
Bee pollen is a rich bee product, from the point of view of its nutritional and functional chemical characteristics. The chemical composition of bee pollen and its properties make this product an excellent food supplement for the human diet, due to its various [...] Read more.
Bee pollen is a rich bee product, from the point of view of its nutritional and functional chemical characteristics. The chemical composition of bee pollen and its properties make this product an excellent food supplement for the human diet, due to its various functional bioactivities, such as having antioxidant, antibacterial, antifungal, and anti-inflammatory properties. These properties depend on the botanical origin of the bee pollen. Castanea sativa bee pollen is one of the most important types of pollen collected in the northwest of the Iberian Peninsula. Thus, the phenolic profile of Castanea bee pollen was featured in this study. For this, 11 samples of Castanea were selected through prior colorimetric separation using the CIELab* scale and verified with palynological analysis. Identification of the main phenol compounds was performed through LC/DAD/ESI-MSn analysis. The phenols compounds were quantified using calibration curves for caffeic acid, quercetin, and naringenin. The main results showed a profile formed of 19 compounds for all samples, although quantitative differences were found. Most of these compounds were phenolamides, with N1, N5, and N10-tricaffeoylspermidine being significantly (p < 0.05) the most abundant. Three isorhamnetin glycoside derivatives and one naringenin were also identified. The richness in phenolamides of Castanea bee pollen identified in this study suggests Castanea bee pollen as a functional food, owing to its healthy properties. Full article
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Article
Development and Validation of a Confirmatory Method for the Determination of 12 Coccidiostat Residues in Eggs and Muscle by Means of Liquid Chromatography Coupled to Hybrid High Resolution Mass Spectrometry
Separations 2023, 10(3), 202; https://doi.org/10.3390/separations10030202 - 14 Mar 2023
Cited by 1 | Viewed by 1009
Abstract
A confirmatory, highly selective multi-residue method based on liquid chromatography coupled to hybrid high resolution mass spectrometry (LC-Q-Orbitrap) was developed and validated for the determination of 12 regulated coccidiostats in eggs and muscle. Particularly, ionophore antibiotics (lasalocid, maduramicin, monensin, narasin, salinomycin and semduramicin) [...] Read more.
A confirmatory, highly selective multi-residue method based on liquid chromatography coupled to hybrid high resolution mass spectrometry (LC-Q-Orbitrap) was developed and validated for the determination of 12 regulated coccidiostats in eggs and muscle. Particularly, ionophore antibiotics (lasalocid, maduramicin, monensin, narasin, salinomycin and semduramicin) and synthetic coccidiostats (diclazuril, halofuginone, nicarbazin as 4,4′-dinitrocarbanilide fraction, robenidine and toltrazuril as toltrazuril-sulphone) were included in the method. The sample preparation consisted in the extraction of the analytes from the matrix with acetonitrile, followed by a clean-up step with Oasis® PRiME HLB SPE and a defatting procedure with n-hexane. Validation was successfully performed according to Commission Implementing Regulation (EU) 2021/808, starting from 1 µg kg−1. The procedure was verified through the analysis of a certified reference material (CRM) and the occurrence of the residues was assessed in the context of the Italian National Residue Control Plan (NRCP). Full article
(This article belongs to the Special Issue Application of Separation Technology in Chemistry)
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Article
Characterization of the Aroma Profile of Food Smoke at Controllable Pyrolysis Temperatures
Separations 2023, 10(3), 176; https://doi.org/10.3390/separations10030176 - 06 Mar 2023
Cited by 1 | Viewed by 1167
Abstract
Smoking is used to give food its typical aroma and to obtain the desired techno-functional properties of the product. To gain a deeper knowledge of the whole process of food smoking, a controllable smoking process was developed, and the influence of wood pyrolysis [...] Read more.
Smoking is used to give food its typical aroma and to obtain the desired techno-functional properties of the product. To gain a deeper knowledge of the whole process of food smoking, a controllable smoking process was developed, and the influence of wood pyrolysis temperature (150–900 °C) on the volatile compounds in the smoking chamber atmosphere was investigated. The aroma profile of smoke was decoded by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). Subsequently, the correlations in the most important substance classes, as well as in individual target components, were investigated by the Pearson test. Phenols and lactones showed an increase over the entire applied temperature range (rT = 0.94 and rT = 0.90), whereas furans and carbonyls showed no strict temperature dependence (rT < 0.6). Investigations on single aroma compounds showed that not all compounds of one substance class showed the same behavior, e.g., guaiacol showed no significant increase over the applied pyrolysis temperature, whereas syringol and hydoxyacetone showed a plateau after 450 °C, and phenol and cyclotene increased linear over the applied temperature range. These findings will help to better understand the production of aroma-active compounds during smoke generation in order to meet consumers preferences. Full article
(This article belongs to the Special Issue Application of Chromatography in Analytical Chemistry)
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Article
Effect of Surfactants on Reverse Osmosis Membrane Performance
Separations 2023, 10(3), 168; https://doi.org/10.3390/separations10030168 - 02 Mar 2023
Cited by 1 | Viewed by 1265
Abstract
The aim of this study was to evaluate the performance of a reverse osmosis (RO) membrane in surfactant removal using various surfactant model aqueous solutions. The separation tests were performed with laboratory scale units in a dead-end configuration. Cellulose Acetate (CA) and Polyamide [...] Read more.
The aim of this study was to evaluate the performance of a reverse osmosis (RO) membrane in surfactant removal using various surfactant model aqueous solutions. The separation tests were performed with laboratory scale units in a dead-end configuration. Cellulose Acetate (CA) and Polyamide (PA) RO membranes were used with nonionic, anionic, or cationic surfactants at a wide range of concentrations. Membrane performance was evaluated using permeate flux and total organic carbon (TOC) rejection. The effects of surfactant type and concentration on RO membranes were assessed. Permeate flux of the PA membrane depended on the surfactant type and concentration. The separation of cationic surfactant aqueous solutions yielded the lowest permeate flux, followed by nonionic and anionic surfactant aqueous solutions, respectively. Surfactant adsorption on the membrane surface occurred at very low concentration of cationic and nonionic surfactants due to electrostatic and hydrophobic interactions, respectively, which affected permeate flux, and micelles did not affect the permeate flux of PA membrane. However, for CA membrane the permeate flux was not affected by the feed solution. Both membranes exhibited satisfactory TOC rejection (92–99%). This study highlights the importance of assessing interactions between membrane material and surfactant molecules to mitigate membrane fouling and guarantee a better performance of the RO membrane. Full article
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Review
Potential of Advanced Oxidation as Pretreatment for Microplastics Biodegradation
Separations 2023, 10(2), 132; https://doi.org/10.3390/separations10020132 - 15 Feb 2023
Cited by 3 | Viewed by 1808
Abstract
In the last two decades, microplastics (MP) have been identified as an emerging environmental pollutant. Due to their small size, MP particles may easily enter the food chain, where they can have adverse effects on organisms and the environment in general. The common [...] Read more.
In the last two decades, microplastics (MP) have been identified as an emerging environmental pollutant. Due to their small size, MP particles may easily enter the food chain, where they can have adverse effects on organisms and the environment in general. The common methods for the removal of pollutants from the environment are not fully effective in the elimination of MP; thus, it is necessary to find a more suitable treatment method(s). Among the various approaches tested, biodegradation is by far the most environmentally friendly and economically acceptable remediation approach. However, it has serious drawbacks, generally related to the rather low removal rate and often insufficient efficiency. Therefore, it would be beneficial to use some of the less economical but more efficient methods as pretreatment prior to biodegradation. Such pretreatment would primarily serve to increase the roughness and hydrophilicity of the surface of MP, making it more susceptible to bioassimilation. This review focuses on advanced oxidation processes (AOPs) as treatment methods that can enhance the biodegradation of MP particles. It considers MP particles of the six most commonly used plastic polymers, namely: polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate and polyurethane. The review highlights organisms with a high potential for biodegradation of selected MP particles and presents the potential benefits that AOP pretreatment can provide for MP biodegradation. Full article
(This article belongs to the Special Issue Separation and Analysis of Micro- and Nanoplastics in the Environment)
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Article
Screening the Efficacy of a Microbial Consortium of Bacteria and Fungi Isolated from Different Environmental Samples for the Degradation of LDPE/TPS Films
Separations 2023, 10(2), 79; https://doi.org/10.3390/separations10020079 - 24 Jan 2023
Cited by 1 | Viewed by 1732
Abstract
In this study, a screening of the efficacy of a microbial consortium of bacteria and fungi isolated from activated sludge, river sediment, and compost for the degradation of LDPE/TPS was performed. According to the morphological and biochemical characterization, eight bacteria, Bacillus sonorensis, [...] Read more.
In this study, a screening of the efficacy of a microbial consortium of bacteria and fungi isolated from activated sludge, river sediment, and compost for the degradation of LDPE/TPS was performed. According to the morphological and biochemical characterization, eight bacteria, Bacillus sonorensis, Bacillus subtilis, Lysinibacillus massiliensis, Bacillus licheniformis, Bacillus indicus, Bacillus megaterium, Bacillus cereus, and Pseudomonas alcaligenes, five molds, Aspergillus sp. 1, Aspergillus sp. 2, Trichoderma sp., Rhizopus sp., Penicillium sp., and Alternaria sp., and a yeast, Candida parapsilosis, were identified. The first experiment E1 was inoculated with microorganisms isolated from activated sludge and river sediment, and E2 with microorganisms isolated from compost. In both experiments, different types of polymeric materials, low density polyethylene (E1-1 and E2-1), thermoplastic starch (E1-2 and E2-2), low density polyethylene + thermoplastic starch (E1-3 and E2-3), low density polyethylene + thermoplastic starch + styrene-ethylene-styrene (E1-4 and E2-4) were added. The obtained results, weight loss, SEM, and FTIR analysis showed that the microorganisms in both experiments were able to degrade polymeric materials. The mixed culture of microorganisms in experiments E1-2 and E2-2 completely degraded TPS (thermoplastic starch). The percent weight losses of LDPE, LDPE+20% TPS, and LDPE+20% TPS+SEBS in experiment E1 were 3.3184%, 14.1152%, and 16.0062% and in experiment E2 were 3.9625%, 20.4520% and 21.9277%, respectively. SEM microscopy shows that the samples with a LDPE matrix exhibited moderate surface degradation and negligible oxidative degradation under the given conditions. FTIR/ATR data demonstrate that degradation was more intense in E2 than in E1. Full article
(This article belongs to the Special Issue Separation and Analysis of Micro- and Nanoplastics in the Environment)
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Article
Multiple Heart-Cutting Two-Dimensional HPLC-UV Achiral–Chiral Analysis of Branched-Chain Amino Acids in Food Supplements under Environmentally Friendly Conditions
Separations 2023, 10(1), 45; https://doi.org/10.3390/separations10010045 - 11 Jan 2023
Cited by 2 | Viewed by 1460
Abstract
A multiple heart-cutting (mLC-LC) two-dimensional HPLC-UV achiral–chiral method for the direct analysis of branched-chain amino acids (BCAAs) in food supplements under environmentally friendly conditions was developed to cope with the very well-known limited chemoselectivity of chromatographic media for enantioselective analysis. Both achiral and [...] Read more.
A multiple heart-cutting (mLC-LC) two-dimensional HPLC-UV achiral–chiral method for the direct analysis of branched-chain amino acids (BCAAs) in food supplements under environmentally friendly conditions was developed to cope with the very well-known limited chemoselectivity of chromatographic media for enantioselective analysis. Both achiral and chiral methods were developed in compliance with the main principles of green chromatography. The achiral analysis was performed isocratically with an optimized ion-pair reversed-phase (IP-RP) method based on a water/EtOH (95:5, v/v) mobile phase containing heptafluorobutyric acid (7 mM) as the IP agent. The achiral method was characterized by a very appreciable performance and was validated before the analysis of the real sample. High recovery values for all compounds (from 97% to 101%) were found in the interday evaluation. Additionally, low RSD% values in the long-term period were measured, in the range between 1.1% and 4.8%. Still, an LOQ value of 0.06 mg/mL was established for all compounds. The quantitative analysis of a commercial food supplement revealed that BCAAs were present in amounts very close to those declared by the producer. The enantioselective analysis was carried out through the application of the chiral ligand-exchange chromatography (CLEC) approach, using O-benzyl-(S)-serine ((S)-OBS, 0.5 mM) as the chiral selector and Cu(II) nitrate (0.25 mM) as the metal source in the eluent. Resolution and separation factor values up to 2.31 and 1.43, respectively, were obtained. The two chromatographic systems were connected through a six-port switching valve, and the developed two-dimensional mLC-LC method confirmed the absence of D-enantiomers of BCAAs in the food supplement, as reported in the manufacturer’s label. Full article
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Article
Study of Different Chiral Columns for the Enantiomeric Separation of Azoles Using Supercritical Fluid Chromatography
Separations 2023, 10(1), 9; https://doi.org/10.3390/separations10010009 - 23 Dec 2022
Cited by 1 | Viewed by 1375
Abstract
The enantiomeric separation of antifungal compounds is an arduous task in pharmaceutical and biomedical fields due to the different properties that each diastereoisomer presents. The enantioseparation of a group of fungicides (sulconazole, bifonazole, triadimefon and triadimenol) using supercritical fluid chromatography was achieved in [...] Read more.
The enantiomeric separation of antifungal compounds is an arduous task in pharmaceutical and biomedical fields due to the different properties that each diastereoisomer presents. The enantioseparation of a group of fungicides (sulconazole, bifonazole, triadimefon and triadimenol) using supercritical fluid chromatography was achieved in this work. For this goal, four different chiral columns based on polysaccharide derivatives, as well as the effect of different chromatographic parameters such as temperature, type and percentage of organic modifier (methanol, ethanol and isopropanol), were thoroughly investigated. The inversion of the elution order of enantiomers as a result of a change in the stationary phase or organic modifier was also evaluated by employing a circular dichroism detector. The best separation conditions, in terms of the enantioresolution and analysis time, were obtained with the Lux® Cellulose-2 column using isopropanol as the organic modifier. Full article
(This article belongs to the Special Issue Women in Separations)
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Article
Phytochemical, Antimicrobial, Antioxidant, and In Vitro Cytotoxicity Evaluation of Echinops erinaceus Kit Tan
Separations 2022, 9(12), 447; https://doi.org/10.3390/separations9120447 - 16 Dec 2022
Cited by 5 | Viewed by 1477
Abstract
Wild plants are used by many cultures for the treatment of diverse ailments. However, they are formed from mixtures of many wanted and unwanted phytochemicals. Thus, there is a necessity to separate the bioactive compounds responsible for their biological activity. In this study, [...] Read more.
Wild plants are used by many cultures for the treatment of diverse ailments. However, they are formed from mixtures of many wanted and unwanted phytochemicals. Thus, there is a necessity to separate the bioactive compounds responsible for their biological activity. In this study, the chemical composition as well as antimicrobial and cytotoxic activities of Echinops erinaceus Kit Tan (Asteraceae) were investigated. This led to the isolation and identification of seven compounds, two of which are new (erinaceosin C3 and erinaceol C5), in addition to methyl oleate (C1) and ethyl oleate (C2), loliolide (C4), (E)-p-coumaric acid (C6), and 5,7,3`,5`-tetrahydroxy flavanone (C7). The structures of the isolated compounds were elucidated by 1D, 2D NMR, and HR-ESI-MS. The methanol extract showed the highest antimicrobial activity among the tested extracts and fractions. The n-hexane and EtOAc extracts showed remarkable antimicrobial activity against B. subtilus, P. aeruginosa, E. coli, and C. albicans. A cytotoxicity-guided fractionation of the most bioactive chloroform extract resulted in the isolation of bioactive compounds C1/C2, which showed significant cytotoxicity against HCT-116 and CACO2 cell lines (IC50 24.95 and 19.74 µg/mL, respectively), followed by compounds C3 (IC50 82.82 and 76.70 µg/mL) and C5 (IC50 99.09 and 87.27 µg/mL), respectively. The antioxidant activity of the bioactive chloroform fractions was screened. Molecular docking was used to explain the results of the antimicrobial and anticancer activities against five protein targets, including DNA gyrase topoisomerase II, enoyl-acyl carrier protein reductase of S. aureus (FabI), dihydrofolate reductase (DHFR), β-catenin, and human P-glycoprotein (P-gp). Full article
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Review
Metabolites of Serratula L. and Klasea Cass. (Asteraceae): Diversity, Separation Methods, and Bioactivity
Separations 2022, 9(12), 448; https://doi.org/10.3390/separations9120448 - 16 Dec 2022
Cited by 3 | Viewed by 1194
Abstract
Serratula L. and Klasea Cass. are two systematically related genera of the family Asteraceae, which are distributed in most of the Eurasia area and are used as food and colorants and in traditional medicines as a drug. Since 1967, 261 metabolites have been [...] Read more.
Serratula L. and Klasea Cass. are two systematically related genera of the family Asteraceae, which are distributed in most of the Eurasia area and are used as food and colorants and in traditional medicines as a drug. Since 1967, 261 metabolites have been isolated and identified from five Serratula species and 21 Klasea species. This review provides information on the chemodiversity of the terpenes, penolics, lipids, and other compounds found in both genera and their occurrence in individual species. Among the studied species, the most studied are S. coronata subsp. coronata, K. centauroides, and K. centauroides subsp. centauroides. This review also provides information on the methods of extraction, isolation, and analysis of ecdysteroids and flavonoids as the most valuable metabolites. For the first time, we provide general information about the biological activity of these extracts and individual compounds. The data presented in this review demonstrate the prospects of Serratula and Klasea species as sources of bioactive metabolites. Full article
(This article belongs to the Special Issue Feature Papers in Separations from Editorial Board Members)
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Article
Capsule Phase Microextraction Combined with Chemometrics for the HPLC Determination of Amphotericin B in Human Serum
Separations 2022, 9(12), 433; https://doi.org/10.3390/separations9120433 - 12 Dec 2022
Viewed by 1311
Abstract
This article discusses the use of a sorbent-based microextraction technique employing a capsule device to isolate amphotericin B (AMB) from human serum before analysis by high performance liquid chromatography (HPLC). AMB is a macrocyclic compound used for the treatment of invasive fungal infections. [...] Read more.
This article discusses the use of a sorbent-based microextraction technique employing a capsule device to isolate amphotericin B (AMB) from human serum before analysis by high performance liquid chromatography (HPLC). AMB is a macrocyclic compound used for the treatment of invasive fungal infections. Before determining AMB in human serum by HPLC, a sample preparation step is required. Capsule phase microextraction (CPME) integrates the stirring and filtration mechanisms in a single unit, simplifying the sample preparation procedure. Moreover, it results in fast extraction kinetics and high extraction efficiency, while it has proved to be a powerful tool for bioanalysis. Different sol–gel sorbent encapsulated microextraction capsules were investigated, and sol–gel Carbowax 20 M was finally chosen as the basis for the microextraction device. Accordingly, the sample preparation protocol was investigated using a face-centered central composite design to achieve good extraction performance. The optimum protocol was validated in terms of linearity, selectivity, limit of detection (LOD), limit of quantitation (LOQ), precision, and accuracy. The linear range of the developed approach was 0.10–10.0 μg mL−1. The LOD value was 0.03 μg mL−1, and the LOQ value was 0.10 μg mL−1. Method accuracy (expressed as relative recovery) was 87–113%, while the relative standard deviation of the repeatability (sr) and within-laboratory reproducibility (sR) were <12.4%. The sol–gel sorbent encapsulated microextraction capsules were reusable for at least 10 extraction cycles. All things considered, the proposed method exhibited good overall performance, and it could be used in bioanalysis for quality control, therapeutic drug monitoring and research purposes. Full article
(This article belongs to the Collection Feature Paper Collection in Section Chromatographic Separations)
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Article
Impact of Sunflower Meal Protein Isolate Supplementation on Pasta Quality
Separations 2022, 9(12), 429; https://doi.org/10.3390/separations9120429 - 10 Dec 2022
Cited by 3 | Viewed by 1483
Abstract
Globally, there is an increased demand for plant- and animal-derived proteins. However, animal-derived proteins are still expensive and expected to negatively impact the environment. Sunflower seeds, an excellent source of proteins, are one of the most critical oilseeds produced in the world markets. [...] Read more.
Globally, there is an increased demand for plant- and animal-derived proteins. However, animal-derived proteins are still expensive and expected to negatively impact the environment. Sunflower seeds, an excellent source of proteins, are one of the most critical oilseeds produced in the world markets. This study used sunflower meal protein isolate (SMPI), wheat flour (WF), and their blends to make pasta with good sensory features and higher nutritional value. The chemical and amino acid compositions, rheological properties, color attributes, cooking quality, sensory properties, and texture analysis of pasta were evaluated. SMPI showed a high protein content (87.12%) compared to WF (10.90%). The pasta was made from WF with supplementing SMPI at three concentrations (3.0, 6.0, and 9.0% w/w) to improve the nutritional quality. Farinograph parameters showed that water absorption, arrival time, dough development time, mixing tolerance index, dough weakening, and dough stability increased as the percentage of SMPI in the blends increased. The results also showed that the color (L*, a*, and b*) of pasta samples was darker as the mixing level of SMPI increased. The obtained sensorial results confirmed this result. The cooking quality of pasta revealed that the weight, volume, and cooking loss of prepared pasta with SMPI (3.0–9.0%) increased compared to the control sample (pasta with 100% WF). Moreover, sensory evaluation of pasta revealed that all samples were acceptable. Nonetheless, mouth feel and overall acceptability of pasta reinforced with 3.0 and 6.0% SMPI did not notably impact the pasta compared to the control sample, while flavor did not significantly influence the pasta with 3.0% SMPI. These findings demonstrated that pasta supplemented with SMPI could benefit the pasta industry, which requires a suitable technological process to obtain novel products. Full article
(This article belongs to the Special Issue Extraction and Utilization of Bioactive Compounds in Food)
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Article
Valorization of Raw Coffee Beans (Coffea arabica and Coffea canephora) through Solvent Development and Extraction of Bioactive Compounds
Separations 2022, 9(12), 423; https://doi.org/10.3390/separations9120423 - 09 Dec 2022
Viewed by 1041
Abstract
Raw coffee beans are seen as valuable sources of bioactive compounds, such as alkaloids and chlorogenic acids. In this study, an efficient and eco-friendly method for the simultaneous extraction of caffeine, trigonelline, and chlorogenic acids from raw beans of two coffee species was [...] Read more.
Raw coffee beans are seen as valuable sources of bioactive compounds, such as alkaloids and chlorogenic acids. In this study, an efficient and eco-friendly method for the simultaneous extraction of caffeine, trigonelline, and chlorogenic acids from raw beans of two coffee species was developed, using green solvents and an unconventional method of extraction (assisted by ultrafast rotary disintegrator/homogenizer (UT-AE)). The experimental extraction conditions were optimized according to a completely randomized design (CRD), considering the following variables: solvent type (four deep eutectic solvents (DESs), water, and aqueous choline chloride solution (50 wt.%); temperature (25, 45, and 65 °C); and extraction technique (solid-liquid extraction with agitated heating and assisted by ultrafast rotary disintegrator/homogenizer). The extract obtained with choline chloride solution (50 wt.%) exhibited high total phenolic compounds and the highest antioxidant capacity. An analysis using high-performance liquid chromatography with a diode array detector (HPLC-DAD) indicated the presence of chlorogenic acids, caffeine, and trigonelline in all the extracts, in different amounts. The results obtained by the analysis of phenolic compounds and HPLC indicated that the aqueous solution of choline chloride (50% wt.%) was the most suitable solvent for the extraction of chlorogenic acids, while the water-based extracts showed high values of caffeine and trigonelline. DESs, in turn, seems to promote a protective effect on the antioxidant activity of biomolecules. Full article
(This article belongs to the Special Issue Research on Sustainable Extraction and Purification of Compounds)
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Article
Advanced Treatment of Direct Dye Wastewater Using Novel Composites Produced from Hoshanar and Sunny Grey Waste
Separations 2022, 9(12), 425; https://doi.org/10.3390/separations9120425 - 09 Dec 2022
Cited by 12 | Viewed by 1168
Abstract
The present project is designed to investigate the potential of hoshanar and sunny grey marble wastes to remove direct violet 51 dye from wastewater using adsorption process. The effect of different parameters such as pH, adsorbent dose, initial dye concentration, and contact time [...] Read more.
The present project is designed to investigate the potential of hoshanar and sunny grey marble wastes to remove direct violet 51 dye from wastewater using adsorption process. The effect of different parameters such as pH, adsorbent dose, initial dye concentration, and contact time were studied to optimize the results of adsorption process. Different isothermic models (Temkin, Langmuir isotherm, Freundlich isotherm, Harkin Jura, and Dubinin-Radushkevich models) and kinetic models (pseudo-first order and pseudo-second order) were employed to adsorption data to find out the best fit model, i.e., Langmuir isotherm and pseudo-second order model. Marble waste composites were also characterized by using different techniques such as scanning electron microscopy (SEM) for surface morphology and Fourier transform infrared spectroscopy (FTIR) to determine chemical arrangements, structure, and functional groups of adsorbents. Hoshanar treated with a mixture of potassium ferricyanide, and sodium meta silicate showed maximum adsorption capacity of 105.31 mg/g as compared to untreated hoshanar (67.19.45 mg/g). So, the conversion of HM into HMPS makes it an affordable, efficient, and available adsorbent for wastewater treatment. Full article
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Review
Mass Spectrometric Methods for Non-Targeted Screening of Metabolites: A Future Perspective for the Identification of Unknown Compounds in Plant Extracts
Separations 2022, 9(12), 415; https://doi.org/10.3390/separations9120415 - 07 Dec 2022
Cited by 1 | Viewed by 2210
Abstract
Phyto products are widely used in natural products, such as medicines, cosmetics or as so-called “superfoods”. However, the exact metabolite composition of these products is still unknown, due to the time-consuming process of metabolite identification. Non-target screening by LC-HRMS/MS could be a technique [...] Read more.
Phyto products are widely used in natural products, such as medicines, cosmetics or as so-called “superfoods”. However, the exact metabolite composition of these products is still unknown, due to the time-consuming process of metabolite identification. Non-target screening by LC-HRMS/MS could be a technique to overcome these problems with its capacity to identify compounds based on their retention time, accurate mass and fragmentation pattern. In particular, the use of computational tools, such as deconvolution algorithms, retention time prediction, in silico fragmentation and sophisticated search algorithms, for comparison of spectra similarity with mass spectral databases facilitate researchers to conduct a more exhaustive profiling of metabolic contents. This review aims to provide an overview of various techniques and tools for non-target screening of phyto samples using LC-HRMS/MS. Full article
(This article belongs to the Special Issue Application of Separation Technology in Chemistry)
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Review
Heterogeneous Catalytic Ozonation: Solution pH and Initial Concentration of Pollutants as Two Important Factors for the Removal of Micropollutants from Water
Separations 2022, 9(12), 413; https://doi.org/10.3390/separations9120413 - 06 Dec 2022
Cited by 3 | Viewed by 919
Abstract
There are several publications on heterogeneous catalytic ozonation; however, their conclusions and the comparisons between them are not always consistent due to the variety of applied experimental conditions and the different solid materials used as catalysts. This review attempts to limit the major [...] Read more.
There are several publications on heterogeneous catalytic ozonation; however, their conclusions and the comparisons between them are not always consistent due to the variety of applied experimental conditions and the different solid materials used as catalysts. This review attempts to limit the major influencing factors in order to reach more vigorous conclusions. Particularly, it highlights two specific factors/parameters as the most important for the evaluation and comparison of heterogeneous catalytic ozonation processes, i.e., (1) the pH value of the solution and (2) the initial concentration of the (micro-)pollutants. Based on these, the role of Point of Zero Charge (PZC), which concerns the respective solid materials/catalysts in the decomposition of ozone towards the production of oxidative radicals, is highlighted. The discussed observations indicate that for the pH range 6–8 and when the initial organic pollutants’ concentrations are around 1 mg/L (or even lower, i.e., micropollutant), then heterogeneous catalytic ozonation follows a radical mechanism, whereas the applied solid materials show their highest catalytic activity under their neutral charge. Furthermore, carbons are considered as a rather controversial group of catalysts for this process due to their possible instability under intense ozone oxidizing conditions. Full article
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Article
Interactions between Hazelnut (Corylus avellana L.) Protein and Phenolics and In Vitro Gastrointestinal Digestibility
Separations 2022, 9(12), 406; https://doi.org/10.3390/separations9120406 - 02 Dec 2022
Cited by 2 | Viewed by 1369
Abstract
In this study, we investigated the formation of protein–phenolic complexes from dephenolized hazelnut meal protein isolates (dHPI) and hazelnut skin phenolic extracts (HSE) and their effects on the bioaccessibility of both hazelnut proteins and phenolics. The dHPI–HSE complexes were of considerable size and [...] Read more.
In this study, we investigated the formation of protein–phenolic complexes from dephenolized hazelnut meal protein isolates (dHPI) and hazelnut skin phenolic extracts (HSE) and their effects on the bioaccessibility of both hazelnut proteins and phenolics. The dHPI–HSE complexes were of considerable size and were dependent on HSE concentration due to aggregation. Although catechin was the main component of HSE, it did not cause aggregation, except for a slight rise in particle size. According to fluorescence quenching, the hazelnut protein–phenolic extract complex had a linear Stern–Volmer plot expressing static quenching between 0–0.5 mM concentration; the interaction was mainly dependent on hydrogen bonding and van der Waals forces (ΔH < 0 and ΔS < 0), and the reaction was spontaneous (ΔG < 0). According to Fourier transform infrared (FTIR) spectroscopy results, higher phenolic extract concentration caused an increase in irregular structures in hazelnut protein, while the lowest catechin and phenolic concentration altered the regular structure. Skin extracts did not alter the digestibility of dephenolized proteins, but dephenolization reduced the degree of hydrolysis by pancreatin. The formation of the protein–phenolic complex had a beneficial effect on the bioaccessibility of hazelnut skin phenols, predominantly those on the galloylated form of the catechins, such as gallocatechin gallate and epigallocatechin gallate. Thus, the bioaccessibility and antioxidant activity analysis results showed that protein–phenolic complexes obtained from hazelnut meal and skin may promote the transition of phenolic compounds from the gastrointestinal tract without degradation. Full article
(This article belongs to the Special Issue Extraction and Application of Functional Components in Food)
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Validation of a Rapid Ultrasound-Assisted Extraction Coupled with Anion Exchange Chromatography Method for the Determination of D-Psicose in Raisin Matrices
Separations 2022, 9(12), 408; https://doi.org/10.3390/separations9120408 - 02 Dec 2022
Viewed by 958
Abstract
D-psicose is a rare sugar, used as an alternative to the natural sweetener that provides 70% of sucrose’s sweetness, with low-calorie absorption in the human body. Considering the health-beneficial effect and high availability of D-psicose in raisins (the world’s most consumed dried fruit), [...] Read more.
D-psicose is a rare sugar, used as an alternative to the natural sweetener that provides 70% of sucrose’s sweetness, with low-calorie absorption in the human body. Considering the health-beneficial effect and high availability of D-psicose in raisins (the world’s most consumed dried fruit), it is of interest to establish a reliable analytical method to determine D-psicose content in these matrices. Herein, a new method for determining D-psicose content in raisins, using ultrasound-assisted extraction in conjunction with anion exchange chromatography with pulsed amperometric detection (UAE-HPAEC-PAD) systems, has been developed and validated. The stability of D-psicose and its precursor was priorly assessed by applying a specific ultrasound power (100 W) and pulse duty cycle (0.5 s−1), with varying extraction temperatures (10, 25, 40, 55, 70, and 85 °C) and times (5, 10, 15, 20, and 25 min). The method was validated with high linearity (R2 > 0.999), accuracy (89.78–101.06%), and precision (4.8% intra-day and 4.34% inter-day). A number of raisin products were checked during the method applicability assessment. A concentration of 520 mg kg−1 was found in a specimen of commercial raisin matrix. Full article
(This article belongs to the Special Issue Separation and Chemical Analysis of Bioactive Ingredients in Food)
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Review
Preparation and Application of Graphene–Based Materials for Heavy Metal Removal in Tobacco Industry: A Review
Separations 2022, 9(12), 401; https://doi.org/10.3390/separations9120401 - 01 Dec 2022
Cited by 2 | Viewed by 2018
Abstract
Heavy metals are nondegradable in the natural environment and harmful to the ecological system and human beings, causing an increased environmental pollution problem. It is required to remove heavy metals from wastewater urgently. Up until now, various methods have been involved in the [...] Read more.
Heavy metals are nondegradable in the natural environment and harmful to the ecological system and human beings, causing an increased environmental pollution problem. It is required to remove heavy metals from wastewater urgently. Up until now, various methods have been involved in the heavy metal removals, such as chemical precipitation, chemical reduction, electrochemical, membrane separation, ion exchange, biological, and adsorption methods. Among them, adsorption by graphene–based materials has attracted much more attentions for the removal of heavy metals from wastewater systems in recent years, arising due to their large specific surface area, high adsorption capacity, high removal efficiency, and good recyclability. Therefore, it is quite important to review the heavy metal removal with the graphene–based material. In this review, we have summarized the physicochemical property and preparation methods of graphene and their adsorption property to heavy metals. The influencing parameters for the removal of heavy metals by graphene–based materials have been discussed. In addition, the modification of graphene–based materials to enhance their adsorption capability for heavy metal removal is also reviewed. The heavy metal removal by modified graphene–based materials in the tobacco industry has been especially described in detail. Finally, the future trend for graphene–based materials in the field of heavy metal wastewater treatment is proposed. This knowledge will have great impacts on the field and facilitate the researchers to seek the new functionalization method for graphene–based materials with high adsorption capacity to heavy metals in the tobacco industry in the future. Full article
(This article belongs to the Special Issue Advances in Separation Engineering)
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Review
In-Tube Solid-Phase Microextraction Directly Coupled to Mass Spectrometric Systems: A Review
Separations 2022, 9(12), 394; https://doi.org/10.3390/separations9120394 - 26 Nov 2022
Cited by 4 | Viewed by 1037
Abstract
Since it was introduced in 1997, in-tube solid-phase microextraction (in-tube SPME), which uses a capillary column as extraction device, has been continuously developed as online microextraction coupled to LC systems (in-tube SPME-LC). In the last decade, new couplings have been evaluated on the [...] Read more.
Since it was introduced in 1997, in-tube solid-phase microextraction (in-tube SPME), which uses a capillary column as extraction device, has been continuously developed as online microextraction coupled to LC systems (in-tube SPME-LC). In the last decade, new couplings have been evaluated on the basis of state-of-the-art LC instruments, including direct coupling of in-tube SPME to MS/MS systems, without chromatographic separation, for high-throughput analysis. In-tube SPME coupling to MS/MS has been possible thanks to the selectivity of capillary column coatings and MS/MS systems (SRM mode). Different types of capillary columns (wall-coated open-tubular, porous-layer open-tubular, sorbent-packed, porous monolithic rods, or fiber-packed) with selective stationary phases have been developed to increase the sorption capacity and selectivity of in-tube SPME. This review focuses on the in-tube SPME principle, extraction configurations, current advances in direct coupling to MS/MS systems, experimental parameters, coatings, and applications in different areas (food, biological, clinical, and environmental areas) over the last years. Full article
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Article
Rapid Determination of Metribuzin and Three Major Transformation Products in Soil and Plant by Gas Chromatography–Tandem Mass Spectrometry
Separations 2022, 9(12), 386; https://doi.org/10.3390/separations9120386 - 23 Nov 2022
Cited by 2 | Viewed by 1332
Abstract
Metribuzin is a pre- and post-emergence triazinone herbicide used in a variety of crops. This herbicide is degraded in the environment into three major metabolites that have high water solubility, high to very high soil mobility, and low to moderate persistence in soil. [...] Read more.
Metribuzin is a pre- and post-emergence triazinone herbicide used in a variety of crops. This herbicide is degraded in the environment into three major metabolites that have high water solubility, high to very high soil mobility, and low to moderate persistence in soil. This paper describes the development of an analytical method based on ultrasound-assisted extraction and GC-MS/MS determination for the determination metribuzin and its main metabolites in soil and plants. The developed method provided good recoveries for all compounds in soil and plants (from 73 to 121%). The quantitation limits obtained from plants (2.6 to 18 µg/kg) allow determining the presence of these compounds at trace levels. To evaluate the applicability of the developed methods, bean plants were grown in plastic pots with soil treated with metribuzin and collected after 23 days. At the end of the assay, only 11% of the initial concentration of metribuzin remained in soil. Metribuzin and its three metabolites were detected in plants, desamino-diketo-metribuzin is the most abundant metabolite. It is expected that the application of these methods can provide more data to monitor metribuzin residues due to herbicide treatments. Full article
(This article belongs to the Special Issue Chromatography-Mass Spectrometry Technology Research)
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Article
Mesoporous Activated Carbon from Bamboo Waste via Microwave-Assisted K2CO3 Activation: Adsorption Optimization and Mechanism for Methylene Blue Dye
Separations 2022, 9(12), 390; https://doi.org/10.3390/separations9120390 - 23 Nov 2022
Cited by 6 | Viewed by 1248
Abstract
Bamboo waste (BW) was activated with a K2CO3 precursor in a microwave process for the adsorption of MB dye from an aqueous solution. The prepared bamboo-waste-activated carbon (BWAC) was analyzed by instrumental techniques such as FTIR, SEM, and BET analysis. [...] Read more.
Bamboo waste (BW) was activated with a K2CO3 precursor in a microwave process for the adsorption of MB dye from an aqueous solution. The prepared bamboo-waste-activated carbon (BWAC) was analyzed by instrumental techniques such as FTIR, SEM, and BET analysis. The surface of the BWAC was mesoporous with a surface area of 107.148 m2/g. The MB dye removal was optimized with the three variables of adsorbent dose, pH, and contact time using the Box–Behnken design (BBD) model. Up to 87% of MB was removed in the optimized conditions of adsorbent dose of 0.08 g/100 mL, pH of 7.62, time of 8 min, and concentration of 50 mg/L. Here, the most effective parameter for MB removal was found to be adsorbent dose with an F-value of 121.70, while time and pH showed a smaller effect. The maximum adsorption capacity of BWAC in the optimized conditions was found to be 85.6 mg/g. The adsorption of MB on BWAC’s surface was through chemisorption and a spontaneous process. The adsorption mechanism study showed that three types of interactions are responsible for the removal of MB dye from aqueous solutions by BWAC, i.e., electrostatic interactions, H-bonding, and pi–pi interactions. Hence, BWAC can be considered a highly efficient adsorbent for MB removal from wastewater. Full article
(This article belongs to the Special Issue Applications of Porous Materials in Adsorption)
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Article
Development of an HPLC-DAD Method for the Extraction and Quantification of 5-Fluorouracil, Uracil, and 5-Fluorodeoxyuridin Monophosphate in Cells and Culture Media of Lactococcus lactis
Separations 2022, 9(11), 376; https://doi.org/10.3390/separations9110376 - 17 Nov 2022
Cited by 2 | Viewed by 2186
Abstract
The drug 5-fluorouracil (5-FU) is a common cancer chemotherapeutic, presenting toxicity. Mild toxicity is treated with administration of probiotics. The interaction of these probiotics with the drug may have a crucial effect on its therapeutic efficacy. In the present work, a method for [...] Read more.
The drug 5-fluorouracil (5-FU) is a common cancer chemotherapeutic, presenting toxicity. Mild toxicity is treated with administration of probiotics. The interaction of these probiotics with the drug may have a crucial effect on its therapeutic efficacy. In the present work, a method for the quantification of uracil, 5-FU, and its active metabolite 5-fluorodeoxyuridin monophosphate in cells and culture medium of the probiotic L. lactis is presented. Extraction using H2O containing 0.05% v/v formic acid (1:5 v/v) was followed by ammonium sulphate protein precipitation and SPE. Analysis was conducted in a Nucleosil column using a gradient of water, formic acid, and acetonitrile. Calibration curves were constructed for 5-FU (5–100 μg/mL), uracil (5–20 μg/mL), and 5-fluorodeoxyuridin monophosphate (5–20 μg/mL) using 5-bromouracil as the internal standard (R2 ≥ 0.999). The photodegradation of 5-FU amounted to 36.2% at 96 h. An administration experiment in the dark revealed a decline in 5-FU concentration in the culture media (88.3%) and uptake by the cells, while the uracil and FdUMP levels increased in the cells. The inactive metabolite 5,6 dihydrofluorouracil was detected in the medium. Our results demonstrate that uptake and metabolism of 5-FU in L. lactis cells leads to a decline in the drug levels and in the formation of both the active and the inactive metabolites of the drug. Full article
(This article belongs to the Special Issue Women in Separations)
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Article
Solid-Phase Extraction and Characterization of Quercetrin-Rich Fraction from Melastoma malabathricum Leaves
Separations 2022, 9(11), 373; https://doi.org/10.3390/separations9110373 - 15 Nov 2022
Cited by 1 | Viewed by 1171
Abstract
This study was focused on the recovery of quercetrin from the crude extract of Melastoma malabathricum leaves using the technique of solid-phase extraction. The process variables and their ranges were screened using one-factor-at-a-time and statistically optimized using the response surface methodology. The results [...] Read more.
This study was focused on the recovery of quercetrin from the crude extract of Melastoma malabathricum leaves using the technique of solid-phase extraction. The process variables and their ranges were screened using one-factor-at-a-time and statistically optimized using the response surface methodology. The results found that 9.13 mg/mL of crude extract required 18.24 mL of 70.5% methanol as the eluent to yield an 86.6% w/w fraction containing 36.02 mg/g of quercetrin. The process increased quercetrin from 1% w/w in the crude extract to 4% w/w in the fraction. Quercetrin was likely to be the compound contributing to antiradical and antidiabetic activities. In silico simulation showed that quercetrin had low binding energy and mostly bound with charged (Glu and Arg) and aromatic (Tyr and Phe) amino acids via hydrogen bonds. Its inhibitory progress against DPP-IV was faster than crude extract at low concentration (<100 µg/mL). Full article
(This article belongs to the Special Issue Advanced Methods for Separation and Analysis of Natural Products)
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Review
Metal-Chelating Peptides Separation Using Immobilized Metal Ion Affinity Chromatography: Experimental Methodology and Simulation
Separations 2022, 9(11), 370; https://doi.org/10.3390/separations9110370 - 14 Nov 2022
Cited by 4 | Viewed by 2217
Abstract
Metal-Chelating Peptides (MCPs), obtained from protein hydrolysates, present various applications in the field of nutrition, pharmacy, cosmetic etc. The separation of MCPs from hydrolysates mixture is challenging, yet, techniques based on peptide-metal ion interactions such as Immobilized Metal Ion Affinity Chromatography (IMAC) seem [...] Read more.
Metal-Chelating Peptides (MCPs), obtained from protein hydrolysates, present various applications in the field of nutrition, pharmacy, cosmetic etc. The separation of MCPs from hydrolysates mixture is challenging, yet, techniques based on peptide-metal ion interactions such as Immobilized Metal Ion Affinity Chromatography (IMAC) seem to be efficient. However, separation processes are time consuming and expensive, therefore separation prediction using chromatography modelling and simulation should be necessary. Meanwhile, the obtention of sorption isotherm for chromatography modelling is a crucial step. Thus, Surface Plasmon Resonance (SPR), a biosensor method efficient to screen MCPs in hydrolysates and with similarities to IMAC might be a good option to acquire sorption isotherm. This review highlights IMAC experimental methodology to separate MCPs and how, IMAC chromatography can be modelled using transport dispersive model and input data obtained from SPR for peptides separation simulation. Full article
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Article
Development of a Chemiluminescent Method in a Microfluidic Device for Ultrasensitive Determination of Okadaic Acid with Highly Efficient Aptamer-Based Isolation
Separations 2022, 9(11), 350; https://doi.org/10.3390/separations9110350 - 07 Nov 2022
Viewed by 1091
Abstract
Rapid detection of okadaic acid (OA) in shellfish is crucial for practical application in food safety analysis. In order to establish a rapid, delicate detection scheme, an OA aptamer was utilized to quickly capture OA from the sample solution with polystyrene microspheres as [...] Read more.
Rapid detection of okadaic acid (OA) in shellfish is crucial for practical application in food safety analysis. In order to establish a rapid, delicate detection scheme, an OA aptamer was utilized to quickly capture OA from the sample solution with polystyrene microspheres as solid phase carriers, and an inner-microchannel dam structure was designed to intercept the aptamer-functionalized microspheres to achieve the separation of OA for detection. Horseradish peroxidase (HRP) is utilized to catalyze the luminescence reaction of luminol-H2O2 solution. Through the direct competition for the aptamer between OA and OA-HRP, the rapid detection of OA can be achieved. The dynamic range of this detection method is 41.3–4.02 ng/mL, and the limit of detection (LOD) and lowest limit of quantitation (LOQ) are 12.4 pg/mL and 41.3 pg/mL, respectively. This miniaturized device enables rapid, ultrasensitive detection of OA, and demonstrates the merits of its field portability and low reagent consumption. The device can be deployed for on-site detection and analysis of marine biotoxins thereof. Full article
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Article
Development and Validation of an HPLC-FLD Method for the Determination of NDMA and NDEA Nitrosamines in Lisinopril Using Pre-Column Denitrosation and Derivatization Procedure
Separations 2022, 9(11), 347; https://doi.org/10.3390/separations9110347 - 04 Nov 2022
Viewed by 1506
Abstract
In order to meet the analytical requirements of the European Medicines Agency (EMA), a new HPLC-FLD method was successfully developed using dansyl chloride for the derivatization and determination of the genotoxic impurities N-Nitrosodimethylamine (NDMA) and N-Nitrosodiethylamine (NDEA) in Lisinopril API and [...] Read more.
In order to meet the analytical requirements of the European Medicines Agency (EMA), a new HPLC-FLD method was successfully developed using dansyl chloride for the derivatization and determination of the genotoxic impurities N-Nitrosodimethylamine (NDMA) and N-Nitrosodiethylamine (NDEA) in Lisinopril API and its final product. Samples’ pretreatment includes liquid–liquid microextraction, denitrosation, and derivatization steps. To optimize the process, the parameters contributing to high sensitivity and yielding reliable results were thoroughly studied and optimized using one-factor-at-a-time and experimental design approaches. The analytes were pre-column derivatized with Dansyl-Cl and analyzed by HPLC-fluorescence (λemem = 340/530) using a C18 column and a mixture of phosphate buffer (pH = 2.8; 20 mM)/acetonitrile 55:45 v/v as the mobile phase. The six-level concentration calibration was shown to be linear, with R equal to 0.9995 for both analytes. The limit of detection (LOD) was satisfactory and equal to 4.7 and 0.04 ng/mL for NDMA and NDEA, respectively. Precision was less than 13.4% in all cases, and the average recoveries were equal to 109.2 and 98.1% for NDMA and NDEA, respectively. The proposed procedure is relatively easy, rapid, and suitable for the determination of the two nitrosamines in routine analysis tests. Full article
(This article belongs to the Special Issue Women in Separations)
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Article
Carbon Dioxide Chemical Absorption Using Diamines with Different Types of Active Centers
Separations 2022, 9(11), 343; https://doi.org/10.3390/separations9110343 - 03 Nov 2022
Viewed by 1180
Abstract
The present research analyzes chemical solvents based on the use of diamines (Ethylenediamine-EDA, 1,2-Dimethylethylenediamine-DMEDA and Tetramethylethylenediamine-TMEDA) for carbon dioxide absorption, taking into account the type of amino centers in the molecules. The presence and type of radicals can affect amine solubility in water, [...] Read more.
The present research analyzes chemical solvents based on the use of diamines (Ethylenediamine-EDA, 1,2-Dimethylethylenediamine-DMEDA and Tetramethylethylenediamine-TMEDA) for carbon dioxide absorption, taking into account the type of amino centers in the molecules. The presence and type of radicals can affect amine solubility in water, reaction mechanism, reaction kinetics, etc. Diamines have been considered interesting candidates for carbon dioxide chemical absorption, observing a high influence of the molecule structure. The present work analyzes a series of solvents based on diamines with the same chain length between amino centers, but different types of radicals. This study shows an important variability in the behavior of these solvents. EDA-based solvents have shown high absorption rates and stability, but carbamate hydrolysis is relatively low, avoiding an increase in carbon dioxide loading. Full article
(This article belongs to the Special Issue Perspectives on CO2 Separation and Capture Technologies)
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Review
Magnetic Technologies and Green Solvents in Extraction and Separation of Bioactive Molecules Together with Biochemical Objects: Current Opportunities and Challenges
Separations 2022, 9(11), 346; https://doi.org/10.3390/separations9110346 - 03 Nov 2022
Cited by 3 | Viewed by 1539
Abstract
Currently, magnetic technology and green solvents are widely used in chemical engineering, environmental engineering and other fields as they are environmentally friendly, easy to operate and highly efficient. Moreover, a magnetic field has positive effect on many physicochemical processes. However, related new methods, [...] Read more.
Currently, magnetic technology and green solvents are widely used in chemical engineering, environmental engineering and other fields as they are environmentally friendly, easy to operate and highly efficient. Moreover, a magnetic field has positive effect on many physicochemical processes. However, related new methods, materials, strategies and applications in separation science still need to be developed. In this review, a series of meaningful explorations of magnetic technologies for the separation of natural products and biologic objects, including magnetic ionic liquids and other magnetic solvents and fluids, magnetic nanoparticles and magnetic fields, and the development of magnetic separators were reviewed. Furthermore, the difficulties in the application and development of magnetic separation technology were discussed on the basis of comparison and data analysis, especially for the selection of magnetic materials and magnetic field sources. Finally, the progress in the development of magnetic separators was also elaborated for researchers, mainly including that of the new high-efficiency magnetic separator through multi-technology integration and the optimization of traditional magnetic separators, which help current techniques break through their bottleneck as a powerful driving force. Full article
(This article belongs to the Section Purification Technology)
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Article
Chemical Composition, Antioxidant, Antimicrobial and Anti-Proliferative Activities of Essential Oils of Rosmarinus officinalis from five Different Sites in Palestine
Separations 2022, 9(11), 339; https://doi.org/10.3390/separations9110339 - 03 Nov 2022
Cited by 4 | Viewed by 1223
Abstract
The chemical profiles of Rosmarinus officinalis L. essential oils, collected from five distinct geographical regions in Palestine, were determined using GC-MS. The major phytochemical classes of R. officinalis EOs were monoterpene hydrocarbon (24.81–78.75%) and oxygenated monoterpenoids (19.01–73.78%), with 1,8-cineole (4.81–37.83%), α-pinene (13.07–51.36%), and [...] Read more.
The chemical profiles of Rosmarinus officinalis L. essential oils, collected from five distinct geographical regions in Palestine, were determined using GC-MS. The major phytochemical classes of R. officinalis EOs were monoterpene hydrocarbon (24.81–78.75%) and oxygenated monoterpenoids (19.01–73.78%), with 1,8-cineole (4.81–37.83%), α-pinene (13.07–51.36%), and camphor (11.95–24.30%) being the most abundant components of the studied oils. Using the DPPH assay, the antioxidant activity of EOs revealed that EO from the Jenin region had the highest antioxidant activity, with an IC50 value of 10.23 ± 0.11 µg/mL, followed by samples from Tulkarm (IC50 = 37.15 ± 2.3 µg/mL) and Nablus (IC50= 38.9 ± 0.45 µg/mL). With MICs of 12.5, 12.5, 6.25, 6.25, and 6.25 µg/mL against MRSA, S. aureus, E. coli, K. pneumonia, and P. vulgaris, respectively, the EO extracted from the Jenin region of Palestine had the greatest antibacterial activity. Furthermore, EOs from Jenin and Nablus demonstrated stronger anti-candida action than the pharmaceutical formulation Fluconazole, with MICs of 0.781, 0.781, and 1.56 µg/mL, respectively. Full article
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Article
Solubility of CO2 in 2-Amino-2-methyl-1-propanol (AMP) and 3-(Methylamino)propylamine (MAPA): Experimental Investigation and Modeling with the Cubic-Plus-Association and the Modified Kent-Eisenberg Models
Separations 2022, 9(11), 338; https://doi.org/10.3390/separations9110338 - 02 Nov 2022
Cited by 2 | Viewed by 1332
Abstract
CO2 capture attracts significant research efforts in order to reduce the volume of greenhouse gases emitted from fossil fuels combustion. Among the studied processes, chemical absorption represents a mature approach and, in this direction, new solvents, alternatives to monoethanolamine (MEA), have been [...] Read more.
CO2 capture attracts significant research efforts in order to reduce the volume of greenhouse gases emitted from fossil fuels combustion. Among the studied processes, chemical absorption represents a mature approach and, in this direction, new solvents, alternatives to monoethanolamine (MEA), have been suggested. In this work, the solubility of CO2 in aqueous solutions of 2-amino-2-methyl-1-propanol (AMP) and 3-(methylamino)propylamine (MAPA), which were recently suggested as constituents of novel phase change solvent mixtures, is experimentally measured at 298, 313, 323, and 333 K and in a wide range of pressures, up to approximately 7 bar. As the available literature experimental data for MAPA aqueous solutions are very limited, the experimental results of this study were compared to respective literature data for AMP, and a very satisfactory agreement was observed. The new experimental data were correlated with the cubic-plus-association (CPA) and the modified Kent-Eisenberg models. It was observed that both models rather satisfactorily correlate the experimental data, with the Kent-Eisenberg model presenting more accurate correlations. Full article
(This article belongs to the Special Issue Perspectives on CO2 Separation and Capture Technologies)
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Article
Ultrahigh-Sensitivity Capillary Electrophoresis Analysis of Trace Amounts of Nitrate and Nitrite in Environmental Water Samples
Separations 2022, 9(11), 333; https://doi.org/10.3390/separations9110333 - 01 Nov 2022
Cited by 3 | Viewed by 1129
Abstract
The role of nitrite (NO2) and nitrate (NO3) is essential in the global nitrogen cycle. Monitoring their concentration in environmental and industrial aqueous samples, surface water, soil, food and agricultural products are of high importance. Especially, the [...] Read more.
The role of nitrite (NO2) and nitrate (NO3) is essential in the global nitrogen cycle. Monitoring their concentration in environmental and industrial aqueous samples, surface water, soil, food and agricultural products are of high importance. Especially, the effect of anthropogenic emission, i.e., intensified agriculture is essential due to the overuse of nitrogen, phosphorus and potassium fertilizers. The most widely utilized methods for nitrate and nitrite determination are colorimetry, potentiometry, UV absorption and liquid chromatography. Among them, UV spectroscopy is the most frequently used technique due to the fact of its versatility and simplicity. However, there are industrial and academic needs to develop new methods to overcome some drawbacks of the currently used techniques such as an inadequate limit of detection and potential interferences with organic compounds in the sample. In this paper, we report on the development of a new analytical method based on capillary electrophoresis separation with high-sensitivity UV detection, capable of measuring trace concentrations of nitrite and nitrate well below the current limits of UV spectroscopy methods. During the development process special attention was paid to practical aspects, i.e., the method was tested to quantify nitrate and nitrite in various surface water samples. Full article
(This article belongs to the Special Issue Feature Papers in Separations from Editorial Board Members)
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Article
Appreciatively Efficient Sorption Achievement to U(VI) from the El Sela Area by ZrO2/Chitosan
Separations 2022, 9(10), 311; https://doi.org/10.3390/separations9100311 - 14 Oct 2022
Cited by 5 | Viewed by 1236
Abstract
The need to get uranium out of leaching liquid is pushing scientists to come up with new sorbents. This study uses the wet technique to improve the U(VI) sorption properties of ZrO2/chitosan composite sorbent. To validate the synthesis of ZrO2 [...] Read more.
The need to get uranium out of leaching liquid is pushing scientists to come up with new sorbents. This study uses the wet technique to improve the U(VI) sorption properties of ZrO2/chitosan composite sorbent. To validate the synthesis of ZrO2/CS composite with Zirconyl-OH, -NH, and -NH2 for U(VI) binding, XRD, FTIR, SEM, EDX, and BET are used to describe the ZrO2/chitosan wholly formed. To get El Sela leaching liquid, it used 150 g/L H2SO4, 1:4 S:L ratio, 200 rpm agitation speed, four hours of leaching period, and particle size 149–100 µm. In a batch study, the sorption parameters are evaluated at pH 3.5, 50 min of sorbing time, 50 mL of leaching liquid (200 mg/L U(VI)), and 25 °C. The sorption capability is 175 mg/g. Reusing ZrO2/CS for seven cycles with a slight drop in performance is highly efficient, with U(VI) desorption using 0.8 M acid and 75 min of desorption time. The selective U(VI) recovery from El Sela leachate was made possible using ZrO2/CS. Sodium diuranate was precipitated and yielded a yellow cake with a purity level of 94.88%. Full article
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Article
Potential Use of Low-Cost Agri-Food Waste as Biosorbents for the Removal of Cd(II), Co(II), Ni(II) and Pb(II) from Aqueous Solutions
Separations 2022, 9(10), 309; https://doi.org/10.3390/separations9100309 - 14 Oct 2022
Cited by 2 | Viewed by 1591
Abstract
We evaluated the potential use of agri-food waste for the removal of heavy metal ions from aqueous solutions and its application in different processes (e.g., water remediation, in the production of biomass enriched in nutritionally significant elements, etc.). Biomasses from grape seed, grape [...] Read more.
We evaluated the potential use of agri-food waste for the removal of heavy metal ions from aqueous solutions and its application in different processes (e.g., water remediation, in the production of biomass enriched in nutritionally significant elements, etc.). Biomasses from grape seed, grape pomace, loquat seed, Calabrese broccoli stem, empty pods of carob and broad bean pods, unripe bitter orange peel, kumquat, orange pulp and Canary Island banana pulp were prepared. The percentages and biosorption capacities were evaluated and compared with those refe-renced using Valencia orange peel (Citrus sinensis Valencia late). These studies allow for easily providing added value to different agri-food wastes. The results show that the proposed biomasses were able to retain the studied metal ions and obtained different percentages, being in some cases above 90%. The highest values were obtained using broad bean pod (Pb(II) (91.5%), Cd(II) (61.7%), Co(II) (40.7%) and Ni(II) (39.7%)). Similar values were observed using grape seed, broccoli stem, carob pod and unripe bitter orange peel. Carob pod for biosorption of Cd(II) is also of great interest. These studies suggest that the agri-food residues evaluated can be applied to prepare effective biosorbents of divalent metal ions from aqueous solutions. Full article
(This article belongs to the Special Issue Removal of Emerging Pollutants and Environmental Analysis)
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Article
Plant Poisons in the Garden: A Human Risk Assessment
Separations 2022, 9(10), 308; https://doi.org/10.3390/separations9100308 - 13 Oct 2022
Cited by 1 | Viewed by 1941
Abstract
A study of the plants, and their associated poisons, in the Poison Garden at The Alnwick Garden was undertaken across a calendar year. By selecting 25 plants in the Poison Garden, we have been able to develop a single chromatographic method for the [...] Read more.
A study of the plants, and their associated poisons, in the Poison Garden at The Alnwick Garden was undertaken across a calendar year. By selecting 25 plants in the Poison Garden, we have been able to develop a single chromatographic method for the determination and quantification of 15 plant toxins by liquid chromatography mass spectrometry (LC-MS). Chromatographic separation was achieved on a C18 column (3.5 µm, 100 × 4.6 mm) with a gradient method using water +0.1% formic acid and methanol +0.1% formic acid. The developed method was validated for precision, linearity, limits of detection and quantification and extraction recoveries. The method showed good linearity with a R2 value of >0.995 for all 15 compounds with good precision of 10.7%, 6.7% and 0.3% for the low, medium and high calibration points, respectively. The LC-MS method was used to analyse 25 plant species, as well as their respective parts (i.e., bulb, flower, fruit, leaf, pollen, seed, stem and root), to assess the human risk assessment to children (aged 1 to <2 years) in relation to the plant toxin and its respective LD50. The analysis found that the greatest potential health risks were due to the ingestion of Colchicum autumnale and Atropa belladonna. As a caution, all identified plants should be handled with care with additional precautionary steps to ensure nil contact by children because of the potential likelihood of hand-to-mouth ingestion. Full article
(This article belongs to the Special Issue Investigating the Urban Environment Using Chemical Analysis)
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Article
In Vitro Cytotoxicity and Spectral Analysis-Based Phytochemical Profiling of Methanol Extract of Barleria hochstetteri, and Molecular Mechanisms Underlying Its Apoptosis-Inducing Effect on Breast and Lung Cancer Cell Lines
Separations 2022, 9(10), 298; https://doi.org/10.3390/separations9100298 - 09 Oct 2022
Cited by 6 | Viewed by 1644
Abstract
The objectives of this research were to carry out GC–MS and LC–MS-based phytochemical profiling of Barleria hochstetteri, as well as flow cytometry-based mechanistic investigations of the cytotoxic effect of its extracts against breast and lung cancer cell lines. This preclinical in vitro [...] Read more.
The objectives of this research were to carry out GC–MS and LC–MS-based phytochemical profiling of Barleria hochstetteri, as well as flow cytometry-based mechanistic investigations of the cytotoxic effect of its extracts against breast and lung cancer cell lines. This preclinical in vitro study was carried out in Saudi Arabia and India, from 11 August to 15 January 2022. Barleria hochstetteri was sequentially extracted using the Soxhlet extraction technique. Utilizing LC–MS and GC–MS methods, the phytochemical profiling was performed. Additionally, the total phenolic compounds and flavonoids were quantified in the plant extract using spectrophotometric techniques. In this study, we first examined the cytotoxicity of the plant extract on non-malignant L929 cells and on the carcinogenic MCF-7 and A549 cell lines. Then, we studied the underlying molecular pathways by means of Anti-Bcl-2, caspase-3, and DNA fragmentation (TUNEL) assays, using flow cytometry. The results revealed phenolic compounds and flavonoids to be the two major components in the methanolic extract of B. hochstetteri, with concentrations of 3210 µg GAE/g dwt and 1863 µg QE/g dwt, respectively. Results from GC–MS and LC–MS analyses revealed the presence of bioactive phytochemicals with known cytotoxicity. From the MTT assay on cell viability, the IC50 of the methanol extract for the MCF-7 and A549 cell lines were 219.67 and 144.30 µg/mL, respectively. With IC50 values of 324.24 and 266.66 µg/mL, respectively, the aqueous and methanol extracts were less toxic when tested against the non-cancerous L929 cell line. The extract caused early and late apoptosis in the tested breast and lung cancer cells by activating caspase-3 and inhibiting Bcl-2 protein, and it also caused cell death via DNA damage, based on flow cytometric and molecular marker analyses. These findings indicate that the methanol extract of B. hochstetteri was cytotoxic on breast cancer and lung cancer cell lines. To uncover cancer-fighting chemicals, there is a need for further research on B. hochstetteri, as it is a promising source of anti-cancer chemotherapeutic drugs. Full article
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Article
Increasing the Accuracy and Optimizing the Structure of the Scale Thickness Detection System by Extracting the Optimal Characteristics Using Wavelet Transform
Separations 2022, 9(10), 288; https://doi.org/10.3390/separations9100288 - 05 Oct 2022
Cited by 1 | Viewed by 908
Abstract
Loss of energy, decrement of efficiency, and decrement of the effective diameter of the oil pipe are among the consequences of scale inside oil condensate transfer pipes. To prevent these incidents and their consequences and take timely action, it is important to detect [...] Read more.
Loss of energy, decrement of efficiency, and decrement of the effective diameter of the oil pipe are among the consequences of scale inside oil condensate transfer pipes. To prevent these incidents and their consequences and take timely action, it is important to detect the amount of scale. One of the accurate diagnosis methods is the use of non-invasive systems based on gamma-ray attenuation. The detection method proposed in this research consists of a detector that receives the radiation sent by the gamma source with dual energy (radioisotopes 241Am and 133Ba) after passing through the test pipe with inner scale (in different thicknesses). This structure was simulated by Monte Carlo N Particle code. The simulation performed in the test pipe included a three-phase flow consisting of water, gas, and oil in a stratified flow regime in different volume percentages. The signals received by the detector were processed by wavelet transform, which provided sufficient inputs to design the radial basis function (RBF) neural network. The scale thickness value deposited in the pipe can be predicted with an MSE of 0.02. The use of a detector optimizes the structure, and its high accuracy guarantees the usefulness of its use in practical situations. Full article
(This article belongs to the Special Issue New Strategies for Oil-Water Separation)
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Article
Anti-Allergic and Antioxidant Potential of Polyphenol-Enriched Fractions from Cyclopia subternata (Honeybush) Produced by a Scalable Process
Separations 2022, 9(10), 278; https://doi.org/10.3390/separations9100278 - 01 Oct 2022
Cited by 1 | Viewed by 1394
Abstract
Anti-allergic activity was previously demonstrated for extracts of Cyclopia subternata Vogel plant material, containing substantial amounts of xanthones, benzophenones, dihydrochalcones, flavanones and flavones. Fractionation of a hot water extract on macroporous resin was performed aiming to increase its potency. Operating conditions for scaled-up [...] Read more.
Anti-allergic activity was previously demonstrated for extracts of Cyclopia subternata Vogel plant material, containing substantial amounts of xanthones, benzophenones, dihydrochalcones, flavanones and flavones. Fractionation of a hot water extract on macroporous resin was performed aiming to increase its potency. Operating conditions for scaled-up fractionation of the extract were determined, using small-scale static and dynamic sorption/desorption experiments. The anti-allergic potential of the fractions was assessed based on inhibition of β-hexosaminidase release from IgE-sensitized RBL-2H3 cells. Given the role of oxidative stress in allergic reactions, the extract and fractions were also tested for their ability to scavenge the superoxide anion radical and inhibit xanthine oxidase (XO), an enzyme involved in its generation. The routine DPPH and ORAC assays were used for determination of the antioxidant capacity of the fractions. 3-β-D-Glucopyranosyl-4-O-β-D-glucopyranosyliriflophenone (IDG) had the lowest affinity for the resin, dictating selection of the optimal separation conditions. The extract was separated into four fractions on XAD1180N, using step-wise gradient elution with EtOH-water solutions. The major phenolic compounds present in the fractions were IDG and 3-β-D-glucopyranosyliriflophenone (fraction 1), mangiferin, isomangiferin, 3′,5′-di-β-D-glucopyranosyl-3-hydroxyphloretin and vicenin-2 (fraction 2), 3′,5′-di-β-D-glucopyranosylphloretin, eriocitrin and scolymoside (fraction 3) and hesperidin and p-coumaric acid (fraction 4). Fractionation was only partially effective in increasing activity compared to the extract, i.e., fractions 2, 3 and 4 in the DPPH and XO assays, fractions 1 and 2 in the ORAC assay and fraction 1 in the β-hexosaminidase release assay. In vivo testing will be required to determine whether the increased activity of fractions is worth the effort and expense of fractionation. Full article
(This article belongs to the Special Issue Isolation, Elucidation and Synthesis of Bioactive Natural Products)
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Article
Synthesis, Characterization, and Performance Evaluation of Hybrid Waste Sludge Biochar for COD and Color Removal from Agro-Industrial Effluent
Separations 2022, 9(9), 258; https://doi.org/10.3390/separations9090258 - 13 Sep 2022
Cited by 21 | Viewed by 1671
Abstract
Agro-waste management processes are evolving through the development of novel experimental approaches to understand the mechanisms in reducing their pollution levels efficiently and economically from industrial effluents. Agro-industrial effluent (AIE) from biorefineries that contain high concentrations of COD and color are discharged into [...] Read more.
Agro-waste management processes are evolving through the development of novel experimental approaches to understand the mechanisms in reducing their pollution levels efficiently and economically from industrial effluents. Agro-industrial effluent (AIE) from biorefineries that contain high concentrations of COD and color are discharged into the ecosystem. Thus, the AIE from these biorefineries requires treatment prior to discharge. Therefore, the effectiveness of a continuous flow bioreactor system (CFBS) in the treatment of AIE using hybrid waste sludge biochar (HWSB) was investigated. The use of a bioreactor with hydraulic retention time (HRT) of 1–3 days and AIE concentrations of 10–50% was used in experiments based on a statistical design. AIE concentration and HRT were optimized using response surface methodology (RSM) as the process variables. The performance of CFBS was analyzed in terms of COD and color removal. Findings indicated 76.52% and 66.97% reduction in COD and color, respectively. During biokinetic studies, the modified Stover models were found to be perfectly suited for the observed measurements with R2 values 0.9741 attained for COD. Maximum contaminants elimination was attained at 30% AIE and 2-day HRT. Thus, this study proves that the HWSB made from biomass waste can potentially help preserve nonrenewable resources and promote zero-waste attainment and principles of circular economy. Full article
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Article
Design of an Experimental Study for the Simultaneous Determination of Cefepime, Piperacillin and Tazobactam Using Micellar Organic Solvent-Free HPLC
Separations 2022, 9(8), 215; https://doi.org/10.3390/separations9080215 - 11 Aug 2022
Cited by 8 | Viewed by 1396
Abstract
Application of Sustainable analytical chemistry concepts has become crucial in order to remove the environmentally harmful impacts originating from the routine use of analytical techniques. Here, a new LC method is developed and its parameters are analyzed, depending on a mixed micellar mobile [...] Read more.
Application of Sustainable analytical chemistry concepts has become crucial in order to remove the environmentally harmful impacts originating from the routine use of analytical techniques. Here, a new LC method is developed and its parameters are analyzed, depending on a mixed micellar mobile phase. This was primarily aimed at getting rid of the use of organic solvents in conventional routine analyses. Combinations of tazobactam (TZB) with piperacillin (PPC) or cefepime (CFM) are commonly used as effective antimicrobial therapies, especially for resistant strains. Therefore, the three drugs were separated and quantified using an organic solvent-free mobile phase. The mixed micellar mobile phase was comprised of 15 mM Brij-35 with 38 mM SDS, adjusted to pH 3.5. Separation was performed by HPLC on monolithic RP-C18 column Chromolith® Performance RP-18e (100 mm × 4.6 mm) at a rate of 1 mL per minute of flow in conjunction with a measurement wavelength 210 nm. The method was found valid and applicable in accordance of precision, and accuracy within ranges of 5–100 µg mL−1 for PPC and CFM and of 0.625–12.5 µg mL−1 for TZB. The quality-by-design technique was used to analyze the effect of modifying the mixed micellar ratios on separation efficiency and conclude their behavior. Finally, the suggested approach was assessed applying the green analytical procedure index against the greenest published methodology to show superiority. Full article
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Article
Metabolomic and Proteomic Profile of Dried Hop Inflorescences (Humulus lupulus L. cv. Chinook and cv. Cascade) by SPME-GC-MS and UPLC-MS-MS
Separations 2022, 9(8), 204; https://doi.org/10.3390/separations9080204 - 06 Aug 2022
Cited by 9 | Viewed by 1836
Abstract
Hop (Humulus lupulus L.) is grown mainly for the production of beer. The flowers of the female plant give it the bitter taste and pungent aroma. There are a large number of hop varieties differing in their α-acid content, essential oil levels [...] Read more.
Hop (Humulus lupulus L.) is grown mainly for the production of beer. The flowers of the female plant give it the bitter taste and pungent aroma. There are a large number of hop varieties differing in their α-acid content, essential oil levels and odor profiles. Aside from their use in brewing, more recently, hops have been used for the pharmacological properties of its derivatives that are of great importance to the pharmaceutical industry. Hop is known to have a fairly complex chemistry characterized by the presence of a variety of sesquiterpenoids, diterpenoids and triterpenoids, phytoestrogens and flavonoids. Additionally, considering the countless applications in the pharmacological sector in recent years, a chemical characterization of the different cultivars is essential to better identify the source of specific secondary metabolites. For this purpose, the dried inflorescences of two hop cultivars, Chinook and Cascade, were investigated using Solid-Phase Microextraction-Gas Chromatography-Mass Spectrometry and Liquid Chromatography-Tandem Mass Spectrometry (SPME-GC-MS and LC-MS-MS) to describe their metabolomic and proteomic profile. Furthermore, thanks to an in-depth statistical survey, it was possible to carry out a comparative study highlighting interesting implications deriving from this investigative study. Full article
(This article belongs to the Special Issue Feature Papers in Separations from Editorial Board Members)
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Article
Simultaneous Extraction of Four Antibiotic Compounds from Soil and Water Matrices
Separations 2022, 9(8), 200; https://doi.org/10.3390/separations9080200 - 02 Aug 2022
Cited by 5 | Viewed by 1560
Abstract
The incidence of antibiotic resistance is on the rise and becoming a major health concern. Analyzing the presence of antibiotic compounds in the environment is critical for determining the potential health effects for humans, animals, and ecosystems. For this study, methods were developed [...] Read more.
The incidence of antibiotic resistance is on the rise and becoming a major health concern. Analyzing the presence of antibiotic compounds in the environment is critical for determining the potential health effects for humans, animals, and ecosystems. For this study, methods were developed to simultaneously isolate and quantify four antibiotics important in human medicine (sulfamethoxazole—SMX, trimethoprim—TMP, lincomycin—LIN, and ofloxacin—OFL) in water and soil matrices. For water analysis, different solid phase extraction (SPE) cartridges (Oasis HLB plus and Phenomenex Strata-X) were compared. The Oasis HLB Plus SPE cartridge provided the highest and most consistent recoveries with 118 ± 5%, 86 ± 4%, 83 ± 5%, and 75 ± 1% for SMX, TMP, LIN, and OFL, respectively. For soil analysis, different pre-treatments (grinding and freeze-drying) and soil extraction methodologies (liquid-solid extraction and accelerated solvent extraction (ASE)) were compared. The ASE system resulted in the highest overall recoveries of SMX, TMP, LIN, and OFL with an optimal extracting solution of acetonitrile/water (v/v, 50:50, pH 2.8). When the soil was ground and freeze-dried, trimethoprim recovery increased and when soil was ground, but not freeze-dried, LIN and OFL recoveries increased, while sulfamethoxazole recoveries decreased when soil was ground and freeze-dried. Based on this research, matrix characteristics, especially pH, as well as the pKa’s and functional groups of the antibiotics need to be carefully considered when attempting to extract antibiotic compounds from a water or soil environment. Full article
(This article belongs to the Special Issue Analytical Separation Techniques for Environmental Analysis)
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Article
Amaranth Oilseed Composition and Cosmetic Applications
Separations 2022, 9(7), 181; https://doi.org/10.3390/separations9070181 - 19 Jul 2022
Cited by 6 | Viewed by 1793
Abstract
Amaranth (Amaranthus cruentus) is a possible alternative to high-nutritional-value crops. Amaranth seeds are considered to be one of the few sources of phytosqualene (up to 8%). The use of squalene and its hydrogenated form squalane in skincare formulations has been steadily [...] Read more.
Amaranth (Amaranthus cruentus) is a possible alternative to high-nutritional-value crops. Amaranth seeds are considered to be one of the few sources of phytosqualene (up to 8%). The use of squalene and its hydrogenated form squalane in skincare formulations has been steadily increasing, and the demand for these compounds is expected to rise continuously. The aim of this study was to investigate the amaranth oilseed as a potential ingredient for cosmetic applications. First, an experimental design and optimization were carried out in order to obtain amaranth oil rich in squalane instead of squalene through catalytic hydrogenation. Under the optimal conditions, the resulting oil was fully hydrogenated, with higher stability, and more suitable for cosmetic uses. Furthermore, the effect of the addition of amaranth oil and squalane on the rheological and sensory characteristics of moisturizing cream formulations was assessed. As expected, higher contents of oil and polyunsaturated fatty acids were obtained by supercritical CO2 extraction, and were used for the next step of the experiment. Optimization of the experimental conditions resulted in fully hydrogenated amaranth oil, with higher stability and rich in squalane. Better quality of moisturizing cream formulations was achieved when W/O formulations were enriched with 2% oil, or by adding 1% oil and 1% squalane. The formulation rich in squalane showed a better overall quality compared to other formulations. Full article
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Article
Zostera marina L.: Supercritical CO2-Extraction and Mass Spectrometric Characterization of Chemical Constituents Recovered from Seagrass
Separations 2022, 9(7), 182; https://doi.org/10.3390/separations9070182 - 19 Jul 2022
Cited by 6 | Viewed by 2132
Abstract
Three types of Zostera marina L. collection were extracted using the supercritical CO2-extraction method. For the purposes of supercritical CO2-extraction, old seagrass ejection on the surf edge, fresh seagrass ejection on the surf edge and seagrass collected in water [...] Read more.
Three types of Zostera marina L. collection were extracted using the supercritical CO2-extraction method. For the purposes of supercritical CO2-extraction, old seagrass ejection on the surf edge, fresh seagrass ejection on the surf edge and seagrass collected in water were used. Several experimental conditions were investigated in the pressure range 50–350 bar, with the used volume of co-solvent ethanol in the amount of 1% in the liquid phase at a temperature in the range of 31–70 °C. The most effective extraction conditions are: pressure 250 Bar and temperature 60 °C for Z. marina collected in sea water. Z. marina contain various phenolic compounds and sulfated polyphenols with valuable biological activity. Tandem mass-spectrometry (HPLC-ESI–ion trap) was applied to detect target analytes. 77 different biologically active components have been identified in Z. marina supercritical CO2-extracts. 38 polyphenols were identified for the first time in Z. marina. Full article
(This article belongs to the Special Issue Metabolite Identification via Liquid Chromatography-Mass Spectrometry)
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Review
Single Cell Protein Production Using Different Fruit Waste: A Review
Separations 2022, 9(7), 178; https://doi.org/10.3390/separations9070178 - 18 Jul 2022
Cited by 19 | Viewed by 5650
Abstract
The single cell protein (SCP) technique has become a popular technology in recent days, which addresses two major issues: increasing world protein deficiency with increasing world population and the generation of substantial industrial wastes with an increased production rate. Global fruit production has [...] Read more.
The single cell protein (SCP) technique has become a popular technology in recent days, which addresses two major issues: increasing world protein deficiency with increasing world population and the generation of substantial industrial wastes with an increased production rate. Global fruit production has increased over the decades. The non-edible parts of fruits are discarded as wastes into the environment, which may result in severe environmental issues. These fruit wastes are rich in fermentable sugars and other essential nutrients, which can be effectively utilized by microorganisms as an energy source to produce microbial protein. Taking this into consideration, this review explores the use of fruit wastes as a substrate for SCP production. Many studies reported that the wastes from various fruits such as orange, sweet orange, mango, banana, pomegranate, pineapple, grapes, watermelon, papaya, and many others are potential substrates for SCP production. These SCPs can be used as a protein supplement in human foods or animal feeds. This paper discusses various aspects in regard to the potential of fruit wastes as a substrate for SCP production. Full article
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Article
CO2 Capture over Activated Carbon Derived from Pulverized Semi-Coke
Separations 2022, 9(7), 174; https://doi.org/10.3390/separations9070174 - 13 Jul 2022
Cited by 7 | Viewed by 1036
Abstract
Pulverized semi-coke was employed as raw material to prepare activated carbon via steam activation and evaluated as a CO2 adsorbent. The effects of the preparation parameters including demineralization, activation temperature, activation time and steam flow on the structure and performance of the [...] Read more.
Pulverized semi-coke was employed as raw material to prepare activated carbon via steam activation and evaluated as a CO2 adsorbent. The effects of the preparation parameters including demineralization, activation temperature, activation time and steam flow on the structure and performance of the synthesized activated carbon were investigated. It was found that the microporous structure of activated carbon was greatly influenced by demineralization order and activation conditions. Demineralization before activation significantly increased the microporous structure of the activated carbon, which was ascribed to the removal of the inorganic fraction. Compared to the commercial activated carbon, activated carbon obtained by employing 150 mL/min steam to treat the demineralized pulverized semi-coke at 700 °C for 70 min possessed a higher CO2/N2 selectivity of 34.4 and good cyclic performance, which was due to its narrow microporosity of 0.55 nm. Furthermore, it was proved that a pore size of smaller than 1 nm is favorable for CO2 sorption. Full article
(This article belongs to the Special Issue Pollution Gas Toxicity Analysis and Purification Technology)
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Article
Fog Droplet Collection by Corona Discharge in a Needle–Cylinder Electrostatic Precipitator with a Water Cooling System
Separations 2022, 9(7), 169; https://doi.org/10.3390/separations9070169 - 06 Jul 2022
Cited by 9 | Viewed by 1666
Abstract
In this study, a needle–cylinder electrostatic precipitator with a water cooling system was designed to enhance the harvest of atmospheric water in wet flue gas. The effects of flow rate, temperature and particles on the collection of fog droplets were investigated. Meanwhile, the [...] Read more.
In this study, a needle–cylinder electrostatic precipitator with a water cooling system was designed to enhance the harvest of atmospheric water in wet flue gas. The effects of flow rate, temperature and particles on the collection of fog droplets were investigated. Meanwhile, the energy efficiency of water collection was analyzed at different voltages. The results show that the current decreases with the increase of air relative humidity under the same voltage, and the breakdown voltage increases obviously. Concurrently, by appropriately reducing the wet flue gas flow velocity, the residence time of fog droplets in the electric field can be increased, fully charging the droplets and improving the water collection efficiency. Moreover, experiments revealed that through decreasing the flue gas temperature, both the water collection rate and energy efficiency can be improved. In addition, the presence of particles in wet gas can improve the water collection rate by 5~8% at different discharge voltages. Finally, based on energy efficiency analysis, with the increase of voltage, although the water collection rate increased, the energy efficiency decreased. Full article
(This article belongs to the Special Issue Separation and Purification Technology in Environmental Remediation)
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Article
Extraction and Evaluation of the Antimicrobial Activity of Polyphenols from Banana Peels Employing Different Extraction Techniques
Separations 2022, 9(7), 165; https://doi.org/10.3390/separations9070165 - 29 Jun 2022
Cited by 11 | Viewed by 4222
Abstract
Polyphenols are natural antioxidants and play a vital role in inhibiting oxidative stress induced by the body’s free radicals. Banana peels are a significant agro-industrial waste. This waste could be utilized to extract polyphenols to process various functional foods and nutraceuticals. An investigation [...] Read more.
Polyphenols are natural antioxidants and play a vital role in inhibiting oxidative stress induced by the body’s free radicals. Banana peels are a significant agro-industrial waste. This waste could be utilized to extract polyphenols to process various functional foods and nutraceuticals. An investigation was executed to extract polyphenols from banana peel using the sonication and maceration techniques. Three different polar solvents, methanol, ethanol and acetone, were used at four different concentrations: 25%, 50%, 75% and 100%. Yield (%), Total Polyphenolic Content (TPC), Total Flavonoid Content (TFC) and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) Radical Scavenging assays were performed. The results from the current study articulate that extraction by sonication yields a higher quantity of polyphenols than the maceration technique. The study also concludes that ethanol leads to better extraction than other solvents used in this study. Full article
(This article belongs to the Special Issue Isolation and Structure Elucidation of Antibacterial Compound)
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Article
A Study of Copper (II) Ions Removal by Reverse Osmosis under Various Operating Conditions
Separations 2022, 9(6), 155; https://doi.org/10.3390/separations9060155 - 20 Jun 2022
Cited by 7 | Viewed by 1842
Abstract
The study aims to treat artificial wastewater contaminated with copper (II) ions by reverse osmosis using (SEPA CF042 Membrane Test Skid-TFC BW30XFR). Several concentrations of feedstock were prepared. Different operating pressure, temperature, and flow rate were applied. The effect of these operating conditions [...] Read more.
The study aims to treat artificial wastewater contaminated with copper (II) ions by reverse osmosis using (SEPA CF042 Membrane Test Skid-TFC BW30XFR). Several concentrations of feedstock were prepared. Different operating pressure, temperature, and flow rate were applied. The effect of these operating conditions on both the amount of Cu (II) removal and the permeate flux was monitored. The results of the study revealed that both the permeate flux and Cu (II) removal amount were directly proportional to the operating pressure and feed temperature but inversely proportional to the feed concentration. In contrast, the feed flow rate showed a negligible effect on the permeate flux and Cu (II) removal amount. The temperature correction factor (TCF) of the membrane was calculated and was found to be directly proportional to the feed temperature but inversely proportional to the applied pressure. It was seen that the concentration and flow rate of that feed did not affect the temperature correction factor. Mathematical models have been developed based on these experimental data for both permeate flux and the Cu (II) removal. It was noted that the permeate flux model matched the experimental data, while the Cu (II) removal model did not show a perfect match. In addition to the above, the research highlights for subsequent studies the possibility of a deep link between experimental work and mathematical models. Full article
(This article belongs to the Special Issue Modeling, Simulation, and Optimization of Membrane Processes)
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