Editorial

6 pages, 177 KiB

Open AccessEditorial

Is Chromatographic Efficiency Possible Using Molecularly Imprinted Stationary Phases?

by W. Rudolf Seitz

Separations 2023, 10(6), 327; https://doi.org/10.3390/separations10060327 - 25 May 2023

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Molecularly imprinted polymers are prepared in the presence of a template. They have been shown to resolve enantiomers when used as stationary phases for liquid chromatography. However, the separation efficiency is not as good as that observed with silica stationary phases. This manuscript [...] Read more.

Molecularly imprinted polymers are prepared in the presence of a template. They have been shown to resolve enantiomers when used as stationary phases for liquid chromatography. However, the separation efficiency is not as good as that observed with silica stationary phases. This manuscript identifies the main problems as the slow transfer kinetics between the mobile and stationary phase and the heterogeneity of the stationary phase binding sites. It suggests that preparing templated polymers that have predominantly or exclusively noncovalent crosslinks is the most promising approach for improving efficiency. Full article

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Research

Jump to: Editorial, Review

15 pages, 2676 KiB

Open AccessArticle

Headspace Solid-Phase Micro-Extraction Method Optimization and Evaluation for the Volatile Compound Extraction of Bronchoalveolar Lung Lavage Fluid Samples

by Antao Gao, Nina Nouri, Keisean Stevenson, Edith T. Zemanick, Jerry A. Nick and Jane E. Hill

Separations 2024, 11(1), 27; https://doi.org/10.3390/separations11010027 - 11 Jan 2024

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Abstract

Headspace solid-phase micro-extraction (HS-SPME) is a prevalent technique in metabolomics and volatolomics research. However, the performance of HS-SPME can vary considerably depending on the sample matrix. As a result, fine-tuning the parameters for each specific sample matrix is crucial to maximize extraction efficacy. [...] Read more.

Headspace solid-phase micro-extraction (HS-SPME) is a prevalent technique in metabolomics and volatolomics research. However, the performance of HS-SPME can vary considerably depending on the sample matrix. As a result, fine-tuning the parameters for each specific sample matrix is crucial to maximize extraction efficacy. In this context, we conducted comprehensive HS-SPME optimization for bronchoalveolar lavage fluid (BALF) samples using two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-ToFMS). Our exploration spanned several HS-SPME parameters, including vial size, dilution factor, extraction time, extraction temperature, and ionic strength. The 10 mL vial size, no sample dilution, extraction time of 50 min, extraction temperature of 45 °C, and 40% salt were identified as the optimized parameters. The optimized method was then evaluated by a pair-wise comparison of ten sets of samples. The results revealed that the optimized method yielded an increase of 340% in total peak area and an increase of 80% in total peak number. Moreover, enhancements were observed across nine major chemical classes in both peak area and number. Notably, the optimized method also doubled the number of volatile compounds consistently detected across BALF samples, from 52 to 108. Full article

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14 pages, 4776 KiB

Open AccessArticle

Investigation of a Hydraulic Channel for Plastic Particles Sorting via Experimental and Numerical Tools

by Monica Moroni

Separations 2024, 11(1), 5; https://doi.org/10.3390/separations11010005 - 20 Dec 2023

Viewed by 1172

Abstract

In recent decades, the versatility of fossil-based polymers has led them to become one of the most used materials for the production of several consumer goods. The destiny of post-consumer plastics is crucial for environmental sustainability. Two are the alternatives to landfilling: (i) [...] Read more.

In recent decades, the versatility of fossil-based polymers has led them to become one of the most used materials for the production of several consumer goods. The destiny of post-consumer plastics is crucial for environmental sustainability. Two are the alternatives to landfilling: (i) energy recovery, i.e., replacement of traditional fuel with plastic litter, and (ii) recycling, i.e., processing of plastic wastes to produce secondary raw materials that may substitute primary raw materials. This work presents the investigation of a device for the hydraulic separation of heterogeneous plastic wastes, which, when properly upscaled, may be efficiently used within recycling plants. This apparatus is suitable for the separation of granules or flakes of plastics with a density higher than 1000 Kg/m³ and may replace existing technologies for mechanical recycling. The purpose of the device is to separate the useful fraction from a mixture of plastics and water introduced inside. The separation procedure efficacy relies on the difference in density, dimension, and shape of the processed plastic particles and on the flow features within the device. Experiments were carried out to test the efficacy of the device as a function of those factors. To increase the range of variation in the key parameters influencing the apparatus’s working principles, Computational Fluid Dynamics was employed to build a numerical model of the device. The validated numerical model suitable to fully characterize the apparatus performance features a hybrid grid with an inner mesh of 3·10⁻³ m size, a careful modeling of the near-wall region, and the k-ω SST turbulent model. Full article

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12 pages, 313 KiB

Open AccessArticle

Chemical Profiling on Bioactive Stilbenoids in the Seeds of Paeonia Species Growing Wild in Greece

by Eleni Dimitropoulou, Konstantia Graikou, Vithleem Klontza and Ioanna Chinou

Separations 2023, 10(10), 540; https://doi.org/10.3390/separations10100540 - 13 Oct 2023

Cited by 1 | Viewed by 1336

Abstract

The seeds of Paeonia clusii Stern subsp. clusii and Paeonia mascula (L.) Mill. subsp. mascula growing wild in Greece, though not previously investigated, has been studied as a source of bioactive stilbenoids and other phenolics. Their methanol extracts were analyzed using ultra high-performance [...] Read more.

The seeds of Paeonia clusii Stern subsp. clusii and Paeonia mascula (L.) Mill. subsp. mascula growing wild in Greece, though not previously investigated, has been studied as a source of bioactive stilbenoids and other phenolics. Their methanol extracts were analyzed using ultra high-performance liquid chromatography—high-resolution mass spectrometry (UHPLC-HRMS), and among the identified metabolites (62), 19 paeoniflorin’s derivatives, 17 flavonoids and 12 stilbenes were detected. Moreover, through classic phytochemical separation procedures, twelve among them were isolated and fully spectrally determined as trans-resveratrol, trans-resveratrol-4′-O-β-D-glucopyranoside, cis-resveratrol-4′-O-β-D-glucopyranoside, trans-gnetin-H, trans-ε-viniferin, luteolin, luteolin-3′-O-β-D-glucopyranoside, luteolin-3′,4′-di-O-β-D-glucopyranoside, apigenin, hispidulin, paeoniflorin and benzoyl-paeoniflorin. All seed extracts were measured for their total phenolic content (TPC), appearing as a rich source (116.04 and 103.63 mg GAE/g extract, respectively), followed by free radical (DPPH) scavenging capacity (75.24% and 91.54% inhibition at the concentration of 200 μg/mL). The evaluation of tyrosinase inhibition for both extracts (61% and 70%, respectively) confirmed the potential for their future application in skin health care, comparable with other paeonies of Chinese origin, which are well-known as skin whitening and anti-aging promoters. Full article

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14 pages, 2556 KiB

Open AccessArticle

Evaluation of BPA and Bis-GMA Release from Recent Dental Composite Materials by LC-MS/MS

by Lígia Lopes-Rocha, Virgínia M. F. Gonçalves, Sara C. Cunha, José O. Fernandes, Teresa Pinho and Maria Elizabeth Tiritan

Separations 2023, 10(8), 455; https://doi.org/10.3390/separations10080455 - 18 Aug 2023

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Abstract

Bisphenol-A (BPA) is a xenoestrogen widely used as a synthetic precursor of resin monomers. There is arise need to acquire BPA-free resin-matrix composites to prevent the health effects of BPA. Six composites with distinctive manufacturer specifications were considered to evaluate the degree of [...] Read more.

Bisphenol-A (BPA) is a xenoestrogen widely used as a synthetic precursor of resin monomers. There is arise need to acquire BPA-free resin-matrix composites to prevent the health effects of BPA. Six composites with distinctive manufacturer specifications were considered to evaluate the degree of release of BPA and bisphenol A-Diglycidyl Methacrylate (Bis-GMA) in a dental composite. The light-cured resin-matrix specimens (n = 5 for each composite type) were incubated at 37 °C in 1 mL of a 75% ethanol–water solution in a sealed amber glass vial for 7 days. The 75% ethanol–water solution was replaced daily and immediately frozen (−20 °C) until liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. BPA was not detected in any studied resin-based materials. However, Bis-GMA was detected in almost all the studied samples during the experiment, except AF and BF. The highest Bis-GMA concentration was released from ED at 67.43 ng/mL, followed by BE, FS, and NC with 40.75 ng/mL, 8.30 ng/mL, and 0.94 ng/mL, respectively. There is a clear need for more precise and standardized analytical methods to assess the short- and long-term release of resin-based materials. Furthermore, manufacturers should be obliged to provide complete details of the chemical composition of dental products and to promote the development of materials without estrogenic potential. Full article

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18 pages, 8195 KiB

Open AccessArticle

Removal of Azo Dyes Orange II and Reactive Black 5 from Aqueous Solutions by Adsorption on Chitosan Beads Modified with Choline Chloride: Urea Deep Eutectic Solvent and FeO

by Óscar Martínez-Rico, Lucía Blanco, Ángeles Domínguez and Begoña González

Separations 2023, 10(8), 426; https://doi.org/10.3390/separations10080426 - 27 Jul 2023

Cited by 1 | Viewed by 780

Abstract

The removal of the azo dyes Orange II (OII) and Reactive Black 5 (RB5) from aqueous solutions was studied using three types of adsorbents derived from chitosan: unmodified chitosan beads (un-Ch), chitosan beads tuned with a deep eutectic solvent (DES) composed of choline [...] Read more.

The removal of the azo dyes Orange II (OII) and Reactive Black 5 (RB5) from aqueous solutions was studied using three types of adsorbents derived from chitosan: unmodified chitosan beads (un-Ch), chitosan beads tuned with a deep eutectic solvent (DES) composed of choline chloride:urea at a 1:2 molar ratio (Ch-DES), along with FeO nanoparticles added to chitosan and modified with DES (Ch-FeO-DES). Both dyes were effectively removed in 3–4 h when Ch-DES beads were used, at a dye concentration range of 25–50 mg/L. The modification with DES improved the removal efficiency to achieve increases of around 32% for OII and 17% for RB5. The adsorbent dosage and the initial dye concentration influenced the adsorption process. Isotherm adsorption models (Langmuir, Freundlich, and Temkin) and kinetic models (pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich models) were applied to identify the adsorption behavior. The process could be characterized by employing the pseudo-second-order kinetic model and fitting it to the monolayer Langmuir isotherm. The adsorption occurred on a monolayer with no interaction among dye molecules when electrostatic forces would determine the attaching of dye molecules on the adsorbent. OII was efficiently desorbed by an alkaline solution, while RB5 was more strongly attached. The adsorbent could be recycled, after regeneration with an acid solution, for at least 5 reuse cycles while still achieving effective OII removal. Reactivation with a diluted EDTA solution allowed the authors to recycle RB5-attached beads, achieving optimum removal in two further uses. Full article

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11 pages, 1826 KiB

Open AccessArticle

Enantioselective Separation of Synthetic Cathinones by Capillary Electrophoresis with Ionic Liquid and Cyclodextrin Buffer Co-Additives

by Jennifer Buchanan Roberts and Christa L. Colyer

Separations 2023, 10(7), 417; https://doi.org/10.3390/separations10070417 - 24 Jul 2023

Viewed by 821

Abstract

The enantioselective separation of synthetic cathinones via capillary electrophoresis with ultraviolet detection (CE-UV) was successfully achieved using an acidic formate buffer with the ionic liquid tetrabutylammonium chloride (TBAC) and beta-cyclodextrin (β-CD) as co-additives. Synthetic cathinones (also known as “bath salts”) belong to a [...] Read more.

The enantioselective separation of synthetic cathinones via capillary electrophoresis with ultraviolet detection (CE-UV) was successfully achieved using an acidic formate buffer with the ionic liquid tetrabutylammonium chloride (TBAC) and beta-cyclodextrin (β-CD) as co-additives. Synthetic cathinones (also known as “bath salts”) belong to a class of unregulated drugs labeled new psychoactive substances (NPS). These drugs are readily available and can cause paranoia, confusion, violence, and suicidal thoughts. The stereochemistry of synthetic cathinones, as with other drugs, can influence their potency, toxicity, metabolism, and interaction with other molecules. Thus, it is important to be able to effectively separate different types of synthetic cathinone as well as to resolve enantiomers of each. A study of buffer additives, pH, and counter ions was conducted to identify a system yielding complete enantioselective separation of synthetic cathinones by capillary electrophoresis. Buffer additives TBAC and β-CD, when used separately, did not afford the desired separation; however, when employed as co-additives, enantiomers of each of six different bath salt standards (pentylone, 4-MEC, methylone, MDPBP, MDPV, and naphyrone) were resolved. Achieving this separation of a complex mixture of closely related illicit drugs by CE using an ionic liquid and cyclodextrin together, as buffer co-additives, may provide a new starting point from which to approach the enantiomeric analysis of other drug samples as syntheses of NPS continue to rapidly evolve to evade regulation and law enforcement. Full article

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14 pages, 1396 KiB

Open AccessArticle

Hollow-Fiber Liquid-Phase Microextraction (HF-LPME) Coupled On-Line to Liquid Chromatography for the Determination of the Herbicides 2,4-Dichlorophenoxyacetic Acid and 2-Methyl-4-chlorophenoxyacetic Acid and Their Main Metabolites in Soil Samples

by Sònia Moret, Manuela Hidalgo and Juan M. Sanchez

Separations 2023, 10(5), 273; https://doi.org/10.3390/separations10050273 - 23 Apr 2023

Cited by 3 | Viewed by 1461

Abstract

The use of hollow-fiber liquid-phase microextraction (HF-LPME) is very promising for the clean-up, enrichment, and analysis of chlorophenoxyacetic acid herbicides and their metabolites from environmental and biological samples. An on-line methodology coupling HF-LPME (using a hydrophobic polypropylene hollow fiber of 57 cm length, [...] Read more.

The use of hollow-fiber liquid-phase microextraction (HF-LPME) is very promising for the clean-up, enrichment, and analysis of chlorophenoxyacetic acid herbicides and their metabolites from environmental and biological samples. An on-line methodology coupling HF-LPME (using a hydrophobic polypropylene hollow fiber of 57 cm length, 0.3 mm i.d., 0.2 μm pore size, and 75% porosity) and HPLC-UV has been developed for the analysis of these compounds in soil samples taken from environments treated with these herbicides. Di-hexyl ether was found to be the best solvent for the enrichment of the target herbicides. The use of supported liquid membranes has shown a high and efficient clean-up of the dissolved organic matter present in soil extracts. The enrichment factors achieved with the on-line methodology have allowed us to reach the detection limits of 0.1–0.3 µg·kg⁻¹ soil, by analyzing 20 mL of alkaline extract as a donor solution and using 1 mL of stripping solution, which has permitted us to detect and follow the presence of these compounds in soil samples until nine days after the application of the herbicide. The on-line method has been applied in a preliminary study to assess the mobility of the chlorophenoxyacetic acid herbicides through soils. It has also been found that degradation of these compounds in soil is relatively fast and some metabolites were detected in soils just one day after the application of the herbicide. The high enrichment factors obtained with the HF-LPME procedure allow for the obtainment of low detection limits, which permits the use of a simple HPLC detector, such as UV, which simplifies and reduces the cost of analyses. Full article

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12 pages, 2443 KiB

Open AccessFeature PaperArticle

SFC and CE—A Comparison of Two Orthogonal Methods for the Analysis of Dihydrochalcones in Apple Leaves

by Michael Zwerger, Sarah Contratti, Valentina Mariano and Markus Ganzera

Separations 2023, 10(4), 239; https://doi.org/10.3390/separations10040239 - 04 Apr 2023

Viewed by 1215

Abstract

In recent years the analysis of natural products has been carried out using a range of approaches, but mainly utilizing liquid chromatography (LC) or gas chromatography (GC). However, alternative approaches with orthogonal selectivity like capillary electrophoresis (CE) and supercritical fluid chromatography (SFC) have [...] Read more.

In recent years the analysis of natural products has been carried out using a range of approaches, but mainly utilizing liquid chromatography (LC) or gas chromatography (GC). However, alternative approaches with orthogonal selectivity like capillary electrophoresis (CE) and supercritical fluid chromatography (SFC) have increasingly been employed as well, even though they are often considered niche techniques only. In this study, we intended to confirm and compare their suitability as reliable state-of-the-art methods for the analysis of bioactive compounds by developing CE and SFC for the analysis of dihydrochalcones (DHCs) in apple leaves. The analytes were chosen as they have shown interesting pharmacological effects, such as anti-inflammatory, anti-tumor and immunomodulatory activities, and also present an interesting analytical challenge due to their structural similarity and polarity range. Both methods were well capable to separate the five standard compounds within short separation times and fulfilling the demands for an environmentally friendly “green” technology. CE as well as the SFC assay were validated for linearity, sensitivity, accuracy and precision according to ICH guidelines and met all respective requirements. Using the optimized methods, several Malus sp. samples were analyzed whereby a significant difference in the qualitative as well as quantitative DHC profile was revealed, with overall DHC concentrations ranging from 5.47% to 17.24%. Full article

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14 pages, 1871 KiB

Open AccessArticle

Cost-Effective Simultaneous Determination of τ- and π-Methylhistidine in Dairy Bovine Plasma from Large Cohort Studies Using Hydrophilic Interaction Ultra-High Performance Liquid Chromatography Coupled to Tandem Mass Spectrometry

by Ioannis Sampsonidis, Maria Marinaki, Anastasia Pesiridou, Helen Gika, Georgios Theodoridis, Nektarios Siachos, Georgios Arsenos and Stavros Kalogiannis

Separations 2023, 10(2), 144; https://doi.org/10.3390/separations10020144 - 20 Feb 2023

Cited by 1 | Viewed by 1763

Abstract

The isomeric metabolites τ- and π-methylhistidine (formerly referred to as 3- and 1-methylhistidine) are known biomarkers for muscle protein breakdown and meat protein intake, frequently used in studies involving humans and animals. In the present study, we report the development and validation of [...] Read more.

The isomeric metabolites τ- and π-methylhistidine (formerly referred to as 3- and 1-methylhistidine) are known biomarkers for muscle protein breakdown and meat protein intake, frequently used in studies involving humans and animals. In the present study, we report the development and validation of a simple HILIC-MS/MS method for individual determination of τ-MH and π-MH in a large cohort of blood plasma samples from dairy cows. Their separate determination was achieved mainly through a mass spectrometry fragment ion study, which revealed that the two isomers exhibited distinct mass spectrometric behaviors at different collision energies. Chromatographic conditions were optimised to achieve better separation, minimizing inter-channel interference to less than 1% in both directions. A simple and effective sample clean-up method facilitated low laboratory manual workload. The analytical method was validated for the determination of τ-MH and π-MH in bovine plasma within a concentration range of 80 to 1600 μg/L and provided good linearity (>0.99 for both curves) and precision (<10%). Overall, the developed method enabled the determination of the two isomers in an efficient and economic-friendly manner suitable for large cohort bovine studies (involving hundreds to thousands of samples) mainly to provide data for statistical use. Full article

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15 pages, 2762 KiB

Open AccessArticle

The Potential of Membrane Contactors in the Pre-Treatment and Post-Treatment Lines of a Reverse Osmosis Desalination Plant

by Alessandra Criscuoli

Separations 2023, 10(2), 129; https://doi.org/10.3390/separations10020129 - 14 Feb 2023

Viewed by 1239

Abstract

The flexibility of membrane contactors (MCs) is highlighted for a reverse osmosis (RO) desalination plant. MCs are applied as pre-treatment for the oxygen removal and the pH reduction of seawater, also as post-treatment for the pH increase of the RO permeate and the [...] Read more.

The flexibility of membrane contactors (MCs) is highlighted for a reverse osmosis (RO) desalination plant. MCs are applied as pre-treatment for the oxygen removal and the pH reduction of seawater, also as post-treatment for the pH increase of the RO permeate and the reduction of the RO brine volume. A decrease of the seawater pH down to neutral values, as needed when coagulation is used in the pre-treatment line of RO, together with an increase of the RO permeate pH up to 7.58, matching the target of produced water, can be obtained without the use of chemicals. Direct Contact Membrane Distillation (DCMD) and Vacuum Membrane Distillation (VMD) are investigated as function of the feed concentration (ranging from 40 g/L to 80 g/L) and temperature (40 °C–80° C). Their performance is compared at parity of operating conditions and in terms of applied driving force. Both distillation systems are able to efficiently reject salts (rejection > 99.99%), while higher distillate fluxes are obtained when a vacuum is applied at the permeate side (15 kg/m²h vs. 6.6 kg/m²h for the 80 g/L feed). Full article

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10 pages, 1550 KiB

Open AccessCommunication

Microbead-Beating Extraction of Polycyclic Aromatic Compounds from Seabird Plasma and Whole Blood

by Vida Moradi, Thor Halldorson, Ifeoluwa Idowu, Zhe Xia, Nipuni Vitharana, Chris Marvin, Philippe J. Thomas and Gregg T. Tomy

Separations 2023, 10(1), 48; https://doi.org/10.3390/separations10010048 - 12 Jan 2023

Cited by 1 | Viewed by 1288

Abstract

Seabirds are widely regarded as an invaluable bioindicator of environmental health. Matrices including eggs and feathers have been used as non-lethal means to assess contaminant burdens. We have developed a new approach for extraction of polycyclic aromatic compounds (PACs) from seabird plasma and [...] Read more.

Seabirds are widely regarded as an invaluable bioindicator of environmental health. Matrices including eggs and feathers have been used as non-lethal means to assess contaminant burdens. We have developed a new approach for extraction of polycyclic aromatic compounds (PACs) from seabird plasma and serum based on automated microbead-beating homogenization and extraction. Commercially available bovine serum and plasma were purposely fortified with a suite of PACs separately at three dosing levels, placed inside a custom-made stainless-steel tube containing ceramic microbeads, and subjected to an extraction process using a Precellys tissue homogenizer. Tubes were shaken forcefully in three-dimensions, facilitating high mass-transfer of PACs from the matrix into the hexane extraction solvent. The accuracy of the method ranged from 55 to 120% and limits of detection and quantitation ranged from 0.1 to 8 and 0.2 to 27 pg/μL, respectively. The method exhibited good repeatability with both inter- and intra-day repeatability < 30%. The developed method represents an effective and efficient approach to extraction of PACs from important biological matrices. Full article

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7 pages, 853 KiB

Open AccessArticle

Ultrahigh-Sensitivity Capillary Electrophoresis Analysis of Trace Amounts of Nitrate and Nitrite in Environmental Water Samples

by Robert Farsang, Zsofia Kovacs, Gabor Jarvas and Andras Guttman

Separations 2022, 9(11), 333; https://doi.org/10.3390/separations9110333 - 01 Nov 2022

Cited by 6 | Viewed by 1617

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

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11 pages, 14504 KiB

Open AccessArticle

Gas Chromatography—High-Temperature Proton-Transfer Reaction Mass Spectrometry as a Novel Tool for Forensic Drug Testing

by Vera Reinstadler, Rene Gutmann, Florian Pitterl, Klaus Winkler and Herbert Oberacher

Separations 2022, 9(11), 328; https://doi.org/10.3390/separations9110328 - 26 Oct 2022

Cited by 1 | Viewed by 1603

Abstract

Proton-transfer reaction mass spectrometry (PTR-MS) is a versatile tool for the mass spectrometric analysis of organic molecules in gaseous samples. Due to its operation principle, PTR-MS is a soft ionization technique generating spectral data typically rich in protonated molecule information. Most of the [...] Read more.

Proton-transfer reaction mass spectrometry (PTR-MS) is a versatile tool for the mass spectrometric analysis of organic molecules in gaseous samples. Due to its operation principle, PTR-MS is a soft ionization technique generating spectral data typically rich in protonated molecule information. Most of the currently reported PTR-MS applications are designed to determine volatile compounds. Herein, we present a redesigned instrumental setup termed “high-temperature (HT)-PTR-MS” with improved capabilities for the analysis of low-volatile compounds. The developed HT-PTR-MS prototype was successfully hyphenated with gas chromatography (GC) to enable qualitative and quantitative analysis of licit and illicit drugs in human blood/plasma samples. Different kinds of spiked and authentic samples were used to evaluate the performance of the GC-HT-PTR-MS in forensic drug testing. Benchmarking against GC-MS with electron ionization demonstrated the improved detection capabilities of GC-HT-PTR-MS in screening applications. On average, one order of magnitude lower limits of detection/identification were reached. Clearly, GC-HT-PTR-MS has the vast potential to complement or even replace established mass spectrometric techniques in forensic drug analysis. Full article

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13 pages, 1486 KiB

Open AccessArticle

Determination of the Loading Capacity and Recovery of Extracellular Vesicles Derived from Human Embryonic Kidney Cells and Urine Matrices on Capillary-Channeled Polymer (C-CP) Fiber Columns

by Lacey S. Billotto, Kaylan K. Jackson and R. Kenneth Marcus

Separations 2022, 9(9), 251; https://doi.org/10.3390/separations9090251 - 07 Sep 2022

Cited by 2 | Viewed by 1404

Abstract

Extracellular vesicles (EVs) are 50–1000 nm membranous vesicles secreted from all cells that play important roles in many biological processes. Exosomes, a smaller-sized subset of EVs, have become of increasing interest in fundamental biochemistry and clinical fields due to their rich biological cargos [...] Read more.

Extracellular vesicles (EVs) are 50–1000 nm membranous vesicles secreted from all cells that play important roles in many biological processes. Exosomes, a smaller-sized subset of EVs, have become of increasing interest in fundamental biochemistry and clinical fields due to their rich biological cargos and their roles in processes such as cell-signaling, maintaining homeostasis, and regulating cellular functions. To be implemented effectively in fundamental biochemistry and clinical diagnostics fields of study, and for their proposed use as vectors in gene therapies, there is a need for new methods for the isolation of large concentrations of high-purity exosomes from complex matrices in a timely manner. To address current limitations regarding recovery and purity, described here is a frontal throughput and recovery analysis of exosomes derived from human embryonic kidney (HEK) cell cultures and human urine specimens using capillary-channeled polymer (C-CP) fiber stationary phases via high performance liquid chromatography (HPLC). Using the C-CP fiber HPLC method for EV isolations, the challenge of recovering purified EVs from small sample volumes imparted by the traditional techniques was overcome while introducing significant benefits in processing, affordability (~5 $ per column), loading (~10¹² particles), and recovery (10¹¹–10¹² particles) from whole specimens without further processing requirements. Full article

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14 pages, 1038 KiB

Open AccessArticle

Homemade Pipette Tip Solid-Phase Extraction for the Simultaneous Determination of 40 Drugs of Abuse in Urine by Liquid Chromatography–Tandem Mass Spectrometry

by Sergi Pascual-Caro, Francesc Borrull, Marta Calull and Carme Aguilar

Separations 2022, 9(9), 233; https://doi.org/10.3390/separations9090233 - 01 Sep 2022

Cited by 3 | Viewed by 2373

Abstract

Pipette tip solid-phase extraction facilitates the handling of low-volume samples and organic solvents in order to achieve more environmentally friendly pre-treatment sample techniques. The use of pipette tip extraction was examined for the quick and simple determination of a heterogeneous group of 40 [...] Read more.

Pipette tip solid-phase extraction facilitates the handling of low-volume samples and organic solvents in order to achieve more environmentally friendly pre-treatment sample techniques. The use of pipette tip extraction was examined for the quick and simple determination of a heterogeneous group of 40 drugs of abuse and some of their metabolites in urine by liquid chromatography coupled to tandem mass spectrometry. Several parameters were studied and optimized, including those which can affect extraction efficiencies, such as the amount of sorbent and the volumes and number of aspirating/dispensing cycles of the sample and organic solvents. The linear range of this method was between the quantification limit and 75 or 100 ng mL⁻¹. Detection limits between 0.025 and 0.500 ng mL⁻¹ and quantification limits from 0.100 to 1.500 ng mL⁻¹ were achieved, which are adequate to determine the studied compounds in urine from drug users. Finally, in order to prove its suitability in toxicological and forensic analyses, the method was successfully applied to 22 urine specimens from women who were starting a detoxification program. Cocaine was the most frequently detected substance, as its presence or the presence of its main metabolite was found in 86% of the analyzed samples. Full article

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17 pages, 2477 KiB

Open AccessArticle

Aqueous Extracts of Fish Roe as a Source of Several Bioactive Compounds

by Marta Guedes, Virgínia M. F. Gonçalves, Maria Elizabeth Tiritan, Rui L. Reis, Helena Ferreira and Nuno M. Neves

Separations 2022, 9(8), 210; https://doi.org/10.3390/separations9080210 - 09 Aug 2022

Cited by 3 | Viewed by 2005

Abstract

Regular consumption of seafood and, in particular, fish has been associated with important health benefits. A fish product that has been increasingly included in the human nutrition is roe. Despite its nutritional value has been established (fatty acid profile and protein content), the [...] Read more.

Regular consumption of seafood and, in particular, fish has been associated with important health benefits. A fish product that has been increasingly included in the human nutrition is roe. Despite its nutritional value has been established (fatty acid profile and protein content), the knowledge of the composition of its aqueous extracts is still limited. This work describes the bioactive compounds profile in the roe-derived aqueous extracts of three different marine species (sardine, horse mackerel and sea bass) using a method based on liquid chromatography coupled to high-resolution mass spectrometry with an electrospray ionisation source (LC-ESI/HRMS). The presence of substances with well-known nutritional and functional properties (e.g., antioxidant and anti-inflammatory properties) was demonstrated, namely essential amino acids (e.g., taurine), peptides (e.g., anserine and carnosine), B-group vitamins (e.g., nicotinamide) and gadusol. Therefore, roe-derived aqueous extracts are excellent sources of bioactive compounds and may be used as a font of functional components for several medical and veterinary applications. Full article

(This article belongs to the Special Issue Feature Papers in Separations from Editorial Board Members)

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18 pages, 4429 KiB

Open AccessEditor’s ChoiceArticle

Metabolomic and Proteomic Profile of Dried Hop Inflorescences (Humulus lupulus L. cv. Chinook and cv. Cascade) by SPME-GC-MS and UPLC-MS-MS

by Paola Nezi, Vittoria Cicaloni, Laura Tinti, Laura Salvini, Matteo Iannone, Sara Vitalini and Stefania Garzoli

Separations 2022, 9(8), 204; https://doi.org/10.3390/separations9080204 - 06 Aug 2022

Cited by 14 | Viewed by 2525

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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Review

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16 pages, 907 KiB

Open AccessReview

Health-Promoting Potential of Millet: A Review

by Ashfak Ahmed Sabuz, Md Rahmatuzzaman Rana, Tanvir Ahmed, Mohammad Mainuddin Molla, Nazmul Islam, Hafizul Haque Khan, Golam Ferdous Chowdhury, Qingyu Zhao and Qun Shen

Separations 2023, 10(2), 80; https://doi.org/10.3390/separations10020080 - 24 Jan 2023

Cited by 6 | Viewed by 10817

Abstract

Being a key source of animal food, millet production has been sharply increasing over the last few years in order to cope with the dietary requirements of the ever-increasing world population. It is a splendid source of essential nutrients such as protein, carbohydrates, [...] Read more.

Being a key source of animal food, millet production has been sharply increasing over the last few years in order to cope with the dietary requirements of the ever-increasing world population. It is a splendid source of essential nutrients such as protein, carbohydrates, fat, minerals, vitamins, and also some other bioactive compounds that eventually help through multiple biological activities, including antioxidant, anti-hyperglycemic, anti-cholesterol, anti-hypertensive, anthropometric effects and regulation of gut microbiota composition. These bioactive compounds, nutrients, and functions of cereal grains can be affected by processing techniques such as decortication, soaking, malting, milling, fermentation, etc. This study discusses the nutritional and functional properties of millet-incorporated foods and their impact on health, based on around 150 articles between 2015 and 2022 from the Web of Science, Google Scholar, Food and Agriculture Organization of the United Nations (FAO), Breeding Bid Survey (BBS), and FoodData Central (USDA) databases. Analyzing literature reviews, it is evident that the incorporation of millet and its constituents into foodstuffs could be useful against undernourishment and several other health diseases. Additionally, this review provides crucial information about the beneficial features of millet, which can serve as a benchmark of guidelines for industry, consumers, researchers, and nutritionists. Full article

(This article belongs to the Special Issue Feature Papers in Separations from Editorial Board Members)

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17 pages, 964 KiB

Open AccessReview

New Challenges in (Bio)Analytical Sample Treatment Procedures for Clinical Applications

by Valentina Greco, Marcello Locatelli, Fabio Savini, Ugo de Grazia, Ottavia Montanaro, Enrica Rosato, Miryam Perrucci, Luigi Ciriolo, Abuzar Kabir, Halil Ibrahim Ulusoy, Cristian D’Ovidio, Imran Ali and Alessandro Giuffrida

Separations 2023, 10(1), 62; https://doi.org/10.3390/separations10010062 - 16 Jan 2023

Cited by 5 | Viewed by 2269

Abstract

The primary cause of poor and ambiguous results obtained from the bioanalytical process is the sample pre-treatment, especially in clinical analysis because it involves dealing with complex sample matrices, such as whole blood, urine, saliva, serum, and plasma. So, the aim of this [...] Read more.

The primary cause of poor and ambiguous results obtained from the bioanalytical process is the sample pre-treatment, especially in clinical analysis because it involves dealing with complex sample matrices, such as whole blood, urine, saliva, serum, and plasma. So, the aim of this review is to focus attention on the classical and new techniques of pre-treatment for biological samples used in the bioanalytical process. We discussed the methods generally used for these types of complex samples. Undoubtedly, it is a daunting task to deal with biological samples because the analyst may encounter a substantial loss of the analytes of interest, or the overall analysis may be too time-consuming. Nowadays, we are inclined to use green solvents for the environment, but without sacrificing analytical performance and selectivity. All the characteristics mentioned above should be added to the difficulty of the withdrawal of samples like blood because it can be an invasive practice. For these reasons, now we can also find in the literature the use of saliva as alternative biological samples and new techniques that do not require substantial sample pre-treatment, such as fabric phase sorptive extraction (FPSE). The text has been divided into the following two distinct parts: firstly, we described clinical applications under different subsections, such as anticancer drugs, antibiotics, vitamins, antivirals, non-steroidal anti-inflammatory drugs, statin, imidazoles, and triazoles. The second part is dedicated to sample preparation techniques for diagnostic purposes and is divided into the following different sample preparation techniques: solid-phase microextraction (SPME), microextraction by packed sorbent (MEPS), dispersive liquid–liquid microextraction (DDLME), and fabric phase sorptive extraction (FPSE). Full article

(This article belongs to the Special Issue Feature Papers in Separations from Editorial Board Members)

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35 pages, 3943 KiB

Open AccessReview

Metabolites of Serratula L. and Klasea Cass. (Asteraceae): Diversity, Separation Methods, and Bioactivity

by Daniil N. Olennikov

Separations 2022, 9(12), 448; https://doi.org/10.3390/separations9120448 - 16 Dec 2022

Cited by 3 | Viewed by 1649

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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