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Separations, Volume 9, Issue 8 (August 2022) – 44 articles

Cover Story (view full-size image): Food Contact Materials (FCMs) are an undervalued source of food contamination and a potential route of human exposure to chemicals that are harmful to the endocrine system. Food and water are the main sources of exposure due to their contact with polymeric packaging materials.
European Regulation 10/2011 on plastics in contact with food requires migration tests on FCMs to evaluate the presence of the listed substances and of not intentionally added substances (NIASs) not listed in the regulation and not subjected to restrictions. NIAS are defined as impurities present in the substances used or reaction intermediates formed during the production process, a reaction, or a product’s decomposition. The presence of NIAS in samples tested implies safety risks. The safety risks associated with these compounds must be assessed in line with internationally recognized principles on risk assessment. View this paper
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Article
Enhancing the Stability of Aerobic Granular Sludge Process Treating Municipal Wastewater by Adjusting Organic Loading Rate and Dissolved Oxygen Concentration
Separations 2022, 9(8), 228; https://doi.org/10.3390/separations9080228 - 22 Aug 2022
Viewed by 366
Abstract
Aerobic granular sludge (AGS) application in treating municipal wastewater has been greatly restricted due to its low stability. It has been found that operation parameters have a great impact on stability. The organic loading rate (OLR) and dissolved oxygen (DO) concentration are two [...] Read more.
Aerobic granular sludge (AGS) application in treating municipal wastewater has been greatly restricted due to its low stability. It has been found that operation parameters have a great impact on stability. The organic loading rate (OLR) and dissolved oxygen (DO) concentration are two very important parameters that impact stability. In this study, the organic loading rate (OLR) and aeration rate were studied to verify their influence on AGS system stability, which is indicated by determining pollutant removal performance, including chemical oxygen demand (COD), ammonia nitrogen, and total nitrogen (TN). The physical and chemical property changes of AGS and the effects of pollutant removal during the formation of AGS were systematically investigated. The AGS was formed after about 25 days and remained stable for about 45–50 days. The AGS was light-yellow globular sludge with an average particle size of 1.25 mm and a sludge volume index (SVI) of 33.9 mL/g. The optimal condition was obtained at an OLR of 4.2 kg COD/m3·d, aeration rate of 4 L/min, and a hydraulic retention time (HRT) of 4 h. The corresponding removal efficiencies of COD, ammonia nitrogen, and TN were 94.1%, 98.4% and 74.1%, respectively. The study shows that the AGS system has great potential for pollutant removal from wastewater. Full article
(This article belongs to the Special Issue Novel Methods and Technology for Wastewater and Sludge Treatment)
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Article
Research into Gas Chromatography–Mass Spectrometry (GC-MS) for Ensuring the Effect of 1 MeV-Accelerated Electrons on Volatile Organic Compounds in Turkey Meat
Separations 2022, 9(8), 227; https://doi.org/10.3390/separations9080227 - 19 Aug 2022
Viewed by 246
Abstract
One of the most important tasks in the food industry is the search for alternative biochemical markers of radiation treatment in dietary, chilled meat products such as chicken and turkey. Major organic volatile chemicals found in meat products can be precisely identified using [...] Read more.
One of the most important tasks in the food industry is the search for alternative biochemical markers of radiation treatment in dietary, chilled meat products such as chicken and turkey. Major organic volatile chemicals found in meat products can be precisely identified using gas chromatography coupled with mass spectrometry. In the response to the needs of the food industry, our research team conducted a series of experiments involving the irradiation of chilled poultry meat using an electron accelerator. The experiments showed that the concentration of pure volatile organic compounds in saline solution dropped exponentially with an increase in the irradiation dose, which proves that these chemicals decomposed when exposed to ionizing radiation. However, when turkey meat was exposed to an electron beam with doses up to 1 kGy, the concentration of alcohols, aldehydes, and ketones peaked, only to decrease with an increase in the irradiation dose up to 2 kGy, and then went up slightly when the irradiation dose was within the range from 2 kGy to 10 kGy. To determine the reason behind the nonlinear dependencies of organic compound concentrations in turkey meat on the irradiation dose, we developed a mathematical model that acknowledges the presence of two opposing processes, those of decomposition and accumulation of organic compounds as a result of the decomposition of other compounds that can be found in turkey meat. Full article
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Article
Preparation of Thermodesorption Tube Standards: Comparison of Usual Methods Using Accuracy Profile Evaluation
Separations 2022, 9(8), 226; https://doi.org/10.3390/separations9080226 - 18 Aug 2022
Viewed by 306
Abstract
In order to quantify organic impurities in gas produced from renewable sources, thermal desorption coupled with GC-MS or GC×GC-MS is very useful. However, the preparation of the standard tubes appears not to be trivial. For that, different strategies, based on commercial setups, have [...] Read more.
In order to quantify organic impurities in gas produced from renewable sources, thermal desorption coupled with GC-MS or GC×GC-MS is very useful. However, the preparation of the standard tubes appears not to be trivial. For that, different strategies, based on commercial setups, have been developed. The goal of this study was to compare the classical manual deposit of a liquid standard solution with other commercial methods such as gas stream assisted deposit and vaporization followed by adsorption assisted by gas stream. A standard mixture of 48 compounds from different families was used for the comparison of the performances of the three strategies using the accuracy profile methodology. A global validation score was attributed to each strategy as well as a score according to family of compounds and boiling point range, in order to provide a detailed comparison of the techniques. On the set of studied molecules, commercial setups were found to be more efficient than the manual deposit. Full article
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Article
The Quality Control of Midecamycin and the Predictive Demarcation between Its Impurities and Components
Separations 2022, 9(8), 225; https://doi.org/10.3390/separations9080225 - 17 Aug 2022
Viewed by 251
Abstract
Midecamycin is a 16-membered macrolide antibiotic. It can inhibit the synthesis of bacterial proteins by blocking up the activity of peptidyl transferase in the 50S ribosome. We used high-resolution mass spectrometry to analyze midecamycin, and quantitatively analyzed of each component of midecamycin produced [...] Read more.
Midecamycin is a 16-membered macrolide antibiotic. It can inhibit the synthesis of bacterial proteins by blocking up the activity of peptidyl transferase in the 50S ribosome. We used high-resolution mass spectrometry to analyze midecamycin, and quantitatively analyzed of each component of midecamycin produced by 18 different companies. The developed methods were validated by assessing linearity, limit of quantitation (LOQ), accuracy, precision, and robustness. Good separations were achieved for all components. Ten components of midecamycin were identified, and the contents of these components were determined in midecamycin produced by different companies. The demarcation between impurities and components of midecamycin was not clear. A ligand-docking model was used for predicting the impurities and components of midecamycin. Components and impurities were docked with the target. The results reported in this article may be important for quality control and the predictive demarcation between impurities and components of midecamycin. Full article
(This article belongs to the Special Issue Isolation and Structure Elucidation of Antibacterial Compound)
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Review
An Overview of Methods for L-Dopa Extraction and Analytical Determination in Plant Matrices
Separations 2022, 9(8), 224; https://doi.org/10.3390/separations9080224 - 17 Aug 2022
Viewed by 309
Abstract
L-dopa is a precursor of dopamine used as the most effective symptomatic drug treatment for Parkinson’s disease. Most of the L-dopa isolated is either synthesized chemically or from natural sources, but only some plants belonging to the Fabaceae family contain significant amounts of [...] Read more.
L-dopa is a precursor of dopamine used as the most effective symptomatic drug treatment for Parkinson’s disease. Most of the L-dopa isolated is either synthesized chemically or from natural sources, but only some plants belonging to the Fabaceae family contain significant amounts of L-dopa. Due to its low stability, the unambiguous determination of L-dopa in plant matrices requires appropriate technologies. Several analytical methods have been developed for the determination of L-dopa in different plants. The most used for quantification of L-dopa are mainly based on capillary electrophoresis or chromatographic methods, i.e., high-performance liquid chromatography (HPLC), coupled to ultraviolet-visible or mass spectrometric detection. HPLC is most often used. This paper aims to give information on the latest developments in the chemical study of L-dopa, emphasizing the extraction, separation and characterization of this compound by chromatographic, electrochemical and spectral techniques. This study can help select the best possible strategy for determining L-dopa in plant matrices using advanced analytical methods. Full article
(This article belongs to the Special Issue New Analytical Techniques in Plant Active Components Analysis)
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Article
Development and Validation of a Sensitive HPLC Assay for Determination of Sparfloxacin According to the European Medicines Agency Guideline
Separations 2022, 9(8), 223; https://doi.org/10.3390/separations9080223 - 17 Aug 2022
Viewed by 177
Abstract
Sparfloxacin, a synthetic antibiotic belonging to the third-generation fluoroquinolones, has numerous pharmacokinetic and microbiological advantages which can make it an excellent candidate for the treatment of infections in sheep. The objective of this study was to develop and validate an analytical HPLC method [...] Read more.
Sparfloxacin, a synthetic antibiotic belonging to the third-generation fluoroquinolones, has numerous pharmacokinetic and microbiological advantages which can make it an excellent candidate for the treatment of infections in sheep. The objective of this study was to develop and validate an analytical HPLC method to quantify sparfloxacin in sheep plasma, following the recommendations set out in the Guideline on Bioanalytical Method Validation of the European Union (EMEA/CHMP/EWP/192217/2009). The HPLC mobile phase consisted of acetonitrile and monopotassium phosphate buffer (1.36 g/L) 49:51 (v/v). Genabilic acid was used as internal standard. Mean retention times for sparfloxacin and genabilic acid were 2.6 and 5.8 min, respectively. The method met all specifications of the EMA guideline, being selective and linear in the range of 0.2–10 µg/mL (R2 ≥ 0.99). Within-run precision ranged between 0.00 and 0.88%, with an accuracy of 90.3–118.0% for the lower limit of quantitation (LLOQ). The LLOQ was 0.2 µg/mL, and no interference from the biological matrix was found. The stability of sparfloxacin in the biological matrix was demonstrated under different storage conditions. Therefore, the method can be used to determine sparfloxacin concentrations in sheep plasma in different types of studies. Full article
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Article
Unlocking the Treasure Box: The Role of HEPES Buffer in Disassembling an Uncommon Ferritin Nanoparticle
Separations 2022, 9(8), 222; https://doi.org/10.3390/separations9080222 - 17 Aug 2022
Viewed by 265
Abstract
Ferritins are ideal nanoparticles as drug delivery systems due to their hollow-sphere structure and the ability to target specific receptors on the cell surface. Here, we develop and characterize a new ferritin derived from the chimeric humanized A. fulgidus one, already designed to [...] Read more.
Ferritins are ideal nanoparticles as drug delivery systems due to their hollow-sphere structure and the ability to target specific receptors on the cell surface. Here, we develop and characterize a new ferritin derived from the chimeric humanized A. fulgidus one, already designed to recognize the TfR1 receptor. Starting from the synthetic gene of this chimeric protein, we replaced two positively charged amino acids with two alanine residues to close the large triangular pores on its surface. These mutations make the protein nanoparticle suitable to incorporate even small therapeutics without leakage. Size-exclusion chromatography shows that the assembling/disassembling of this new protein cage can be easily fine-tuned by varying the HEPES buffer and MgCl2 concentration. The protein cage can be opened using 150 mM HEPES buffer without magnesium ions. Adding this divalent cation to the solution promotes the quick assembly of the ferritin as a 24-mer. The development of this new protein cage paves the way for encapsulation and delivery studies of small molecules for therapeutic and diagnostic purposes. Full article
(This article belongs to the Special Issue New Insights in Natural/Recombinant Protein and Peptide Purification)
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Article
New Approach for Trace Thallium Removal in High Purity Ammonium Rhenate Solution by P204 Extraction
Separations 2022, 9(8), 221; https://doi.org/10.3390/separations9080221 - 17 Aug 2022
Viewed by 242
Abstract
Thallium (Tl) is an extremely toxic rare metal to the eco-environment. Trace thallium impurity in ammonium perrhenate is harmful to the high-temperature mechanical properties of rhenium metal used for aeroengine single crystal blade. The di(2-ethylhexyl) phosphoric acid (P204) extraction to remove thallium in [...] Read more.
Thallium (Tl) is an extremely toxic rare metal to the eco-environment. Trace thallium impurity in ammonium perrhenate is harmful to the high-temperature mechanical properties of rhenium metal used for aeroengine single crystal blade. The di(2-ethylhexyl) phosphoric acid (P204) extraction to remove thallium in ammonium perrhenate solution without additive was innovatively proposed. The migration behavior of trace thallium with the concentration of P204, saponification degree and organic/aqueous phase (O/A) ratio, distribution law of thallium in the extraction system of P204, and mechanism of thallium removal were revealed. It was found Tl removal was rapidly increased to 98.5%, at conditions of P204 0.75 mol/L saponified 70% by ammonia, Tl 3.27 mg/L, O/A 1:1, T 298.15 ± 2 K, 250 rpm, and 3 min. McCabe-Thiele Tl extraction equilibrium isotherms indicates Tl concentration of raffinate less than 18.7 μg/L, a theoretical extraction of two stages and a theoretical stripping of two stages are required when both O/A work lines were at 1.0. Therefore, the method of the P204 solvent extraction system can effectively extract Tl in the forms of TlA(org), TlA3(org), TlOHA2(org), and Tl(OH)2A(org). Meanwhile, the new approach can be a promising process for ammonium rhenate refining. Full article
(This article belongs to the Collection State of the Art in Analysis of Energies)
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Article
Two New HPLC Methods, Assessed by GAPI, for Simultaneous Determination of Four Antipsychotics in Pharmaceutical Formulations: A Comparative Study
Separations 2022, 9(8), 220; https://doi.org/10.3390/separations9080220 - 15 Aug 2022
Viewed by 377
Abstract
Antipsychotics are widely used to treat various mental disorders. Combination therapies were approved by the FDA to treat manic states. Quetiapine fumarate, aripiprazole, asenapine maleate, and chlorpromazine HCl are frequently used for treatment of these disorders. Green analytical chemistry is primarily concerned with [...] Read more.
Antipsychotics are widely used to treat various mental disorders. Combination therapies were approved by the FDA to treat manic states. Quetiapine fumarate, aripiprazole, asenapine maleate, and chlorpromazine HCl are frequently used for treatment of these disorders. Green analytical chemistry is primarily concerned with reducing waste generated during sample preparation or analysis. Green solvents, such as ethanol, are being used in HPLC as an alternative to acetonitrile. To this purpose, two new chromatographic methods were developed to determine these four drugs simultaneously in their bulk and pharmaceutical formulations. The greenness of both methods was assessed by the green analytical procedure index (GAPI)—one of them was found to be green ecofriendly, and the other had some environmental hazards (conventional)—and this helps laboratories to choose a method that suits their capabilities. The chromatographic separation for both methods was carried out on a Thermo® C18 column. The total separation times were about 11 min and 9 min for the green and the conventional methods, respectively. Using the Student’s t-test and the F-ratio, there was no significant difference between the results of the two methods. These methods have been validated and successfully applied to the analysis of commercial pharmaceutical formulations. Our study could successfully be used in central quality control laboratories, which need a single analytical method to separate more than one compound with similar pharmacological action. Full article
(This article belongs to the Special Issue Application of Chromatography in Analytical Chemistry)
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Article
Selective Accumulation of Rare-Earth and Heavy Metal Ions by a Fucoidan-Inorganic Composite Material
Separations 2022, 9(8), 219; https://doi.org/10.3390/separations9080219 - 14 Aug 2022
Viewed by 310
Abstract
The accumulation of rare-earth and heavy metal ions from wastewater is important for industrial technology. However, practical accumulators of metal ions are expensive with respect procurement of raw materials, synthesis, and preparation. Therefore, it is preferable to accumulate metal ions using sustainable resources, [...] Read more.
The accumulation of rare-earth and heavy metal ions from wastewater is important for industrial technology. However, practical accumulators of metal ions are expensive with respect procurement of raw materials, synthesis, and preparation. Therefore, it is preferable to accumulate metal ions using sustainable resources, such as natural polymers. Fucoidan, a water-soluble natural polymer, is a sulfated polysaccharide from the cell-wall of brown algae. Therefore, fucoidan behaves as an acidic polysaccharide in an aqueous solution. We prepared a fucoidan-inorganic composite material by mixing fucoidan and a silane coupling reagent, bis(3-(trimethoxysilyl)propyl)amine (SiNSi). This fucoidan-SiNSi (F-SiNSi) composite material showed a water-insoluble property. This is due to the encapsulation of fucoidan into a three-dimensional network of SiNSi with siloxane bonding. When the F-SiNSi composite material is immersed in a metal ion-containing aqueous solution, the composite material accumulated the metal ions. The binding affinity of each metal ion was Ca(II), Mg(II) << Nd(III) < Cu(II), Zn(II), Ni(II), La(III) < In(III) < Y(III). Additionally, the maximum-accumulated amounts of the Nd(III), Cu(II), Zn(II), Ni(II), La(III), In(III), and Y(III) ions were 140, 200, 190, 200, 200, 230, and 270 nmol per mg of fucoidan, respectively. Furthermore, the molar ratios of the acidic groups (the sulfate and carboxyl groups) in the fucoidan and accumulated metal ions, were 0.081–0.156. Therefore, the F-SiNSi composite material showed a selectivity for rare-earth and heavy metal ions. The accumulation mechanism of the rare-earth and heavy metal ions was related to the carboxyl groups in the fucoidan. Full article
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Article
LC-MS/TOF Characterization and Stability Study of Artesunate in Different Solvent Systems
Separations 2022, 9(8), 218; https://doi.org/10.3390/separations9080218 - 13 Aug 2022
Viewed by 349
Abstract
Artemisinin (ART) is a sesquiterpene lactone and a popular malaria drug used in many parts of the world. Artesunate (ARTS) is a semi-synthetic derivative of ART with improved pharmacokinetic properties. However, the half-life of ARTS is less than an hour in vivo. The [...] Read more.
Artemisinin (ART) is a sesquiterpene lactone and a popular malaria drug used in many parts of the world. Artesunate (ARTS) is a semi-synthetic derivative of ART with improved pharmacokinetic properties. However, the half-life of ARTS is less than an hour in vivo. The analysis of this drug in vitro in different solvent systems using LC-MS/TOF showed a solvent-driven breakdown. ARTS breakdown formed several derivatives, including dihydroartemisinin (DHA), artemether (ARTM) and DHA-dimer among others, at different rates in different solvent composition systems. The change in temperature from room temperature to physiological temperature (37 °C) was found to enhance the rate of the ARTS breakdown. In methanol, ARTS mainly formed ARTM with a chromatographic peak decrease of about 3.13%, while methanol and water (90:10) v/v mainly gave rise to DHA and ARTM with about an 80% chromatographic peak decrease. On the other hand, ARTS in methanol and ammonium acetate (85:15) v/v formed DHA, ARTM, DHA-dimer and other reaction peaks with about a 97% peak decrease and the formation of an orange solution pointing to a molecular re-arrangement reaction. These results have an important bearing on research on the analysis of artemisinin drugs conducted on these common solvents. Full article
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Article
Quality by Design Approach for a Multicomponent Quantification Using HPLC-PDA and HPLC-MS: Application to Dosage Form and Biological Body Fluids
Separations 2022, 9(8), 217; https://doi.org/10.3390/separations9080217 - 12 Aug 2022
Viewed by 318
Abstract
A multicomponent pharmaceutical that contains loratadine, paracetamol, and pseudoephedrine was quantified using HPLC-PDA. The three analytes were well-separated and quantified in the dosage form on a C-18 column using a gradient mobile phase. A quality by design strategy was followed to achieve the [...] Read more.
A multicomponent pharmaceutical that contains loratadine, paracetamol, and pseudoephedrine was quantified using HPLC-PDA. The three analytes were well-separated and quantified in the dosage form on a C-18 column using a gradient mobile phase. A quality by design strategy was followed to achieve the challenging separation. Screening and optimization steps were carried out to investigate the effect of many factors on the studied responses with a minimum number of runs. The ANOVA of the factorial model showed that % acetonitrile (factor A), flow rate (factor B), and pH (factor C) were significant. The detection of the analytes’ peaks was carried out using a PDA detector at 248nm for loratadine and paracetamol, and 214 nm for pseudoephedrine. The second method was SPE-HPLC-MS, where the three analytes and desloratadine, the active metabolite of loratadine, were quantified in spiked plasma and urine, using betamethasone valerate as an internal standard. The recovery of the analytes from body fluids was above 96%, and the LOQ was below 0.5 ng/mL. The validation of the developed HPLC-PDA method was achieved as per ICH guidelines, whereas the HPLC-MS method was validated according to FDA guidelines for bioanalytical method validation. The results were compared with the reported method, and no significant differences were found. Full article
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Article
The Nonlinear Dynamic Behavior of a Particle on a Vibrating Screen Based on the Elastoplastic Contact Model
Separations 2022, 9(8), 216; https://doi.org/10.3390/separations9080216 - 12 Aug 2022
Viewed by 274
Abstract
The dynamic response of particles is closely related to screening efficiency. To study the dynamic response of particles, the dynamic equations of a particle on a screening surface are established based on the elastoplastic contact model of spherical particles and are solved for [...] Read more.
The dynamic response of particles is closely related to screening efficiency. To study the dynamic response of particles, the dynamic equations of a particle on a screening surface are established based on the elastoplastic contact model of spherical particles and are solved for the coal particle. Then, the trajectories of the particles are given with different falling heights and particle radii. The completely different trajectories with slight changes in the falling height and particle radius indicate strong nonlinearity. Second, the nonlinear dynamic behavior under different amplitudes and frequencies is discussed, and the route of transition from quasiperiodic motion to chaotic motion is revealed. Finally, we discuss the average speed along the screening surface considering the frequency, amplitude, friction coefficient, inclination angle, and vibration direction angle. In addition, the convergence conditions of particle motion are proposed, and they are only affected by the inclination angle and friction angle. The results show that in the normal direction of the vibrating screen, the particle motion is quasiperiodic at low frequencies. With increasing frequency, the motion of the particle becomes chaotic, and its Poincaré map becomes petal-shaped. In addition, the number of petals increases at the mutation of the bifurcation diagram. The increase in frequency, amplitude and inclination angle and the decrease in friction coefficient lead to an increase in particle speed along the screen surface. In addition, the particle speed reaches a maximum when the vibration direction angle is 65°. This work provides a theoretical basis for controlling the thickness of granular material flow on a vibrating screen and selecting screening process parameters. Full article
(This article belongs to the Special Issue Mineral Flotation)
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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
Viewed by 318
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
Development of a Novel HPLC-MS Method to Separate Polar and Non-Polar Compounds in Biodiesel/Petrodiesel Mixtures
Separations 2022, 9(8), 214; https://doi.org/10.3390/separations9080214 - 11 Aug 2022
Viewed by 243
Abstract
Due to a trend to higher sustainability, biodiesel is often mixed into petrodiesel. The analysis of these blends on a molecular level is not trivial, since huge differences in concentrations and polarity of the analytes require a large dynamic range of the analytical [...] Read more.
Due to a trend to higher sustainability, biodiesel is often mixed into petrodiesel. The analysis of these blends on a molecular level is not trivial, since huge differences in concentrations and polarity of the analytes require a large dynamic range of the analytical method, as well as the ability to investigate molecules of widely different polarities. A combination of high-performance liquid chromatography (HPLC) with high resolution mass spectrometry (HRMS) was identified as a promising method and a normal-phase (NP)-HPLC using amino-functionalized silica gel-based stationary phase delivered the best results with very fast (under 4 min) measurements, with distinct separation of the compounds and clean mass spectra of singular compounds. This method can also be easily modified to elute all FAMEs (fatty acid methyl esters) in one singular peak, thus making the separation even faster (under 3 min). Full article
(This article belongs to the Section Analysis of Energies)
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Article
Method Development and Validation for Simultaneous Analysis of Eleven Components for Quality Control of Geumgwesingihwan Using HPLC–DAD and UPLC–MS/MS
Separations 2022, 9(8), 213; https://doi.org/10.3390/separations9080213 - 10 Aug 2022
Viewed by 295
Abstract
Geumgwesingihwan (GGSGH) is an oriental herbal formula made by adding Achyranthes bidentate Blume and Plantago asiatica L. to Yukmijiwhanghwan. It has been used for the treatment of edema since ancient times. The purpose of this study is to develop and validate a method [...] Read more.
Geumgwesingihwan (GGSGH) is an oriental herbal formula made by adding Achyranthes bidentate Blume and Plantago asiatica L. to Yukmijiwhanghwan. It has been used for the treatment of edema since ancient times. The purpose of this study is to develop and validate a method for simultaneous quantification of 11 components: gallic acid (1), 5-(hydroxymethyl)furfural (2), geniposidic acid (3), morroniside (4), loganin (5), paeoniflorin (6), acteoside (7), cornuside (8), benzoic acid (9), benzoylpaeoniflorin (10), and paeonol (11), using high-performance liquid chromatography with a diode array detector (HPLC–DAD) and ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS). Compounds 111 were separated on a Capcell Pak UG 80 C18 column (250 mm × 4.6 mm, 5 μm) using a mobile phase of a distilled water–acetonitrile system, both containing 0.1% formic acid. In UPLC–MS/MS, compounds 111 were separated on an Acquity UPLC BEH C18 column (100 mm × 2.1 mm, 1.7 µm) using a mobile phase of a distilled water–acetonitrile system containing 1.0% acetic acid. Using these methods, samples of GGSGH were determined to contain 0.13–2.87 mg/g (HPLC–DAD) and not detected–4.60 mg/g (UPLC–MS/MS) of compounds 111. The developed HPLC–DAD assays for simultaneous determination of all analytes were validated with respect to linearity, limits of detection and quantification, recovery, and precision. The established HPLC assay will be used to obtain basic data for quality evaluation of GGSGH and related oriental herbal formulas. Full article
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Article
Classification Performance of a Novel Hydraulic Classifier Equipped with a W-Shaped Reflector
Separations 2022, 9(8), 212; https://doi.org/10.3390/separations9080212 - 10 Aug 2022
Viewed by 274
Abstract
In the present research, we propose the use of a novel hydraulic classifier equipped with a W-shaped reflector to enhance classification performance. The effects of the structural dimensions of a W-shaped reflector on the flow field of a classifier and its classification performance [...] Read more.
In the present research, we propose the use of a novel hydraulic classifier equipped with a W-shaped reflector to enhance classification performance. The effects of the structural dimensions of a W-shaped reflector on the flow field of a classifier and its classification performance were investigated using numerical simulations and experiments. The results demonstrate that the reflection of the W-shaped reflector results in the return of the feed material back to the classification cavity. After this, the materials are mixed with a rising water flow in order to avoid the settlement of particles. Thus, the particles can stay longer in the classification cavity, facilitating the generation of a suspension bed and effectively improving the classification efficiency and accuracy. Our data indicates that the overall classification efficiency of the classifier embedded with the W-shaped reflector was 11.19% higher than that of a traditional classifier. Our results provide a reference for classifier optimization. Full article
(This article belongs to the Special Issue Research on Separation Performance of Separator)
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Article
Laurus azorica: Valorization through Its Phytochemical Study and Biological Activities
Separations 2022, 9(8), 211; https://doi.org/10.3390/separations9080211 - 09 Aug 2022
Viewed by 352
Abstract
Laurus azorica (Seub.) Franco is an endemic species from the Azores, traditionally used in all the islands as a seasoning in cooking. The studies carried out with this species refer mainly to its essential oils. The study that was developed here allowed, for [...] Read more.
Laurus azorica (Seub.) Franco is an endemic species from the Azores, traditionally used in all the islands as a seasoning in cooking. The studies carried out with this species refer mainly to its essential oils. The study that was developed here allowed, for the first time, to determine the chemical composition and biological activities of the ethanol extract, fractions, and pure compounds from L. azorica. The hexane fraction was analyzed by GC–MS and revealed the presence of 48 compounds, comprising mainly fatty acids, fatty alcohols and terpenes, the family of fatty alcohols identified here for the first time in the genus Laurus. Three sesquiterpene lactones—costunolide, 11,13-dehydrosantonin and reynosin—were isolated for the first time in L. azorica from the same fraction, and structurally characterized using spectroscopic techniques. The compounds identified belong to families known to have relevant medicinal and nutritional properties. Regarding antioxidant activities, the results obtained showed a moderate radical scavenging effect of extracts and fractions, while in the β-carotene bleaching assay, costunolide was shown to be the most active (IC50 = 4.08 ± 0.76 μg/mL), about 3.6 times more active than the standard, gallic acid, which presented IC50 = 14.56 ± 0.13 μg/mL. Although the inhibition of extracellular matrix-degrading enzymes was not detected, the ethanol extract showed good inhibitory activity of tyrosinase, with an IC50 of 12.04 ± 0.23 μg/mL, only 6.6-fold lower than the control kojic acid. The results presented deepen the knowledge about a little studied species, opening new perspectives for the development of value-added applications in the food and cosmeceutical fields. Full article
(This article belongs to the Special Issue Identification and Analysis of Compounds in Food Samples)
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Article
Aqueous Extracts of Fish Roe as a Source of Several Bioactive Compounds
Separations 2022, 9(8), 210; https://doi.org/10.3390/separations9080210 - 09 Aug 2022
Viewed by 404
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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Review
Identification of Epigallocatechin-3-Gallate (EGCG) from Green Tea Using Mass Spectrometry
Separations 2022, 9(8), 209; https://doi.org/10.3390/separations9080209 - 09 Aug 2022
Viewed by 378
Abstract
In an era where humanity is reinstating its lost hope and expectation on natural products, green tea occupies quite a position for what it has proven to be, in its endeavors for human welfare and health. Epigallocatechin-3-gallate (EGCG) is the key to the [...] Read more.
In an era where humanity is reinstating its lost hope and expectation on natural products, green tea occupies quite a position for what it has proven to be, in its endeavors for human welfare and health. Epigallocatechin-3-gallate (EGCG) is the key to the vast biological activities of green tea. Green tea is no longer in the backdrop; it has emerged as the most viral, trending bioactive molecule when it comes to health benefits for human beings. This review focuses on the use of various analytical techniques for the analysis of EGCG. That which has been achieved so far, in terms of in vitro, pure component analysis, as well as those spikes in biological fluids and those in vivo in animal and human samples, was surveyed and presented. The use of MS-based techniques for the analysis of EGCG is elaborately reviewed and the need for improvising the applications is explained. The review emphasizes that there is plenty of room to explore matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) applications in this subject area. Full article
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Review
Occurrence, Distribution and Health Risk of Short-Chain Chlorinated Paraffins (SCCPs) in China: A Critical Review
Separations 2022, 9(8), 208; https://doi.org/10.3390/separations9080208 - 08 Aug 2022
Viewed by 378
Abstract
With being listed in the Stockholm Convention, the ban on short-chain chlorinated paraffins (SCCPs) has been put on the agenda in China. Based on the literature over the past decade, this study comprehensively analyzed the occurrence, distribution of and human exposure to SCCPs [...] Read more.
With being listed in the Stockholm Convention, the ban on short-chain chlorinated paraffins (SCCPs) has been put on the agenda in China. Based on the literature over the past decade, this study comprehensively analyzed the occurrence, distribution of and human exposure to SCCPs in China, aiming to provide a reference for the changes in SCCPs after the ban. SCCPs were ubiquitous in environmental matrices, and the levels were considerably higher than those in other countries. SCCPs from the emission region were 2–4 orders of magnitude higher than those in the background area. Environmental processes may play an important role in the SCCP profiles in the environment, and C10 and Cl6 were identified as potential factors distinguishing their spatial distribution. River input was the dominant source in the sea areas, and atmospheric transport was the main source in the remote inland areas. Ingestion and dermal absorption and food intake may pose potential risk to residents, especially for children and infants. More studies are needed on their temporal trend, source emission and environmental degradation. The enactment of the restriction order will have a great impact on China’s CP industry; nevertheless, it will play a positive role in the remediation of SCCP pollution in the environment. Full article
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Article
Extraction and Physicochemical Composition of Irvingiagabonensis Almond Oil: A Potential Healthy Source of Lauric-Myristic Oil
Separations 2022, 9(8), 207; https://doi.org/10.3390/separations9080207 - 08 Aug 2022
Viewed by 347
Abstract
Irvingia gabonensis is a non-timber forest product, whose fruit contains an edible fat-rich kernel. This fat can be used not only in human food but also as a source of raw materials in the cosmetic, pharmaceutical and nutraceutical industries. This work aimed to [...] Read more.
Irvingia gabonensis is a non-timber forest product, whose fruit contains an edible fat-rich kernel. This fat can be used not only in human food but also as a source of raw materials in the cosmetic, pharmaceutical and nutraceutical industries. This work aimed to provide a physicochemical description of components present in the almonds and butter of I. gabonensis. Oil was extracted by soxhlet and hot-pressing from almonds. Cryo-MEB analyses allowed the observation of oleosomes in which the triglycerides of almonds are located. The triglyceride profile and the fatty acids profile of the butter were determined by gas chromatography, and a statistical analysis was performed. The thermal properties of oil were analyzed by thermogravimetric analysis. The results revealed that oil bodies have sizes ranging from 30 to 60 µm. With a 63.8 ± 0.2% fat content, I. gabonensis is composed of 98.4% triglycerides. The hot-pressing yield is 47.9%. The main triglycerides are essentially made up of lauric (38.5 ± 0.1%) and myristic (51.9 ± 0.2%) acids. Thermogravimetric analysis showed that the butter melted at 43.4 °C and decomposed at 415.2 °C. These results show that I. gabonensis butter may be proposed as a good source of lauric acid for food and nutrition. Full article
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Article
Ecofriendly Validated RP-HPTLC Method for Simultaneous Determination of the Bioactive Sesquiterpene Coumarins Feselol and Samarcandin in Five Ferula Species Using Green Solvents
Separations 2022, 9(8), 206; https://doi.org/10.3390/separations9080206 - 08 Aug 2022
Viewed by 298
Abstract
An environmentally friendly unreported rapid and simple reverse-phase high-performance thin-layer chromatography (RP-HPTLC) has been designed for the simultaneous determination of bioactive sesquiterpene coumarins feselol and samarcandin in the methanol extract of five Ferula species. The method was developed using glass plates coated with [...] Read more.
An environmentally friendly unreported rapid and simple reverse-phase high-performance thin-layer chromatography (RP-HPTLC) has been designed for the simultaneous determination of bioactive sesquiterpene coumarins feselol and samarcandin in the methanol extract of five Ferula species. The method was developed using glass plates coated with RP-18 silica gel 60 F254S and a green solvent system of ethanol–water mixture (8:2 v/v) as mobile phase. After development, the plates were quantified densitometrically at 254 for feselol and samarcandin. Feselol and samarcandin peaks from methanol extract of five Ferula species were identified by comparing their single band at Rf = 0.43 ± 0.02 and Rf = 0.60 ± 0.01, respectively. Valid linear relationships between the peak areas and concentrations of feselol and samarcandin in the range of 1000–7000 ng/band respectively were obtained. The method was subjected to the validation criteria of the international conference on harmonization (ICH) for precision, accuracy, and robustness. The new method provides an analytical tool to enumerate the therapeutic doses of feselol and samarcandin in herbal formulations and/or crude drugs. The obtained results indicated that F. drudeana was the richest species in the more active samarcandin, with 0.573% w/w, while F. duranii had the largest quantity of the less active feselol, 0.813% w/w. F. drudeana was superior to the other species in the sum of the two active compounds, 1.4552% w/w, and was consequently expected to be the most active aphrodisiac among the five studied species. Full article
(This article belongs to the Special Issue Extraction and Analysis of Plant Active Ingredients)
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Article
A Multi-Analytical Characterization of Mortars from Kathmandu (Nepal) Historical Monuments
Separations 2022, 9(8), 205; https://doi.org/10.3390/separations9080205 - 07 Aug 2022
Viewed by 308
Abstract
The historical monuments of the ‘City of Temples’ (Kathmandu) represent an intrinsic component of Nepal’s cultural heritage. The 2015 devastating Gorkha earthquake, besides human casualties, has led to a widespread demolition or partial damage of monuments at UNESCO World Heritage Sites, including the [...] Read more.
The historical monuments of the ‘City of Temples’ (Kathmandu) represent an intrinsic component of Nepal’s cultural heritage. The 2015 devastating Gorkha earthquake, besides human casualties, has led to a widespread demolition or partial damage of monuments at UNESCO World Heritage Sites, including the ones in Durbar squares. This study, through an integrated material characterization of masonry binders, used in four case monuments from Hanuman Dhoka and Patan Durbar squares, intends to contribute to the knowledge of the technological know-how of the past in order to maintain as much as possible the original traditions and to provide appropriate conservation strategies. The analytical characterization of the ancient mortars was carried out by means of X-ray Diffraction (XRD), Attenuated Total Reflectance–Fourier Transform-Infrared Spectroscopy (ATR-FTIR), Thermogravimetric Analysis (TGA), petrographic analysis, X-ray Fluorescence spectroscopy (XRF) and Pyrolysis–Gas Chromatography–Mass Spectrometry (Py-GC-MS). The composition of the mortars has been determined and is in accordance with previous research in traditional materials used in the Nepalese architecture. Chromatographic techniques proved to be particularly important in the analysis of mortars with organic binders as they revealed the possible composition of the binding media, providing additional information valuable for the future conservation/restoration of the stone monuments of the ‘City of Temples’. Full article
(This article belongs to the Special Issue Chromatography in Our Cultural Heritage)
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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
Viewed by 462
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
Separation of Monosaccharide Anomers on Photo-Click Cysteine-Based Stationary Phase: The α/β Interconversion Process Studied by Dynamic Hydrophilic Liquid Chromatography
Separations 2022, 9(8), 203; https://doi.org/10.3390/separations9080203 - 05 Aug 2022
Viewed by 344
Abstract
In High-Performance Liquid Chromatography (HPLC), the separation of reducing sugars can typically show three possible typologies of chromatographic profiles (i.e., single peak, two resolved peaks and two peaks interconnected by a plateau) due to the rate at which the relevant α/β anomers interconversion [...] Read more.
In High-Performance Liquid Chromatography (HPLC), the separation of reducing sugars can typically show three possible typologies of chromatographic profiles (i.e., single peak, two resolved peaks and two peaks interconnected by a plateau) due to the rate at which the relevant α/β anomers interconversion (anomerization) can take place in relation to their elution-time. By analyzing these chromatographic profiles, thermodynamic and kinetic properties of anomerization phenomenon can be extrapolated. In this work we studied the anomerization of some monosaccharides by using a recently developed photo-click cysteine-based stationary phase through dynamic hydrophilic interaction liquid chromatography (D-HILIC) conditions. In the 5–25 °C temperature range, the ΔG#α→β and ΔG#β→α barriers were found to achieve values within the interval 21.1/22.2 kcal/mol for glucose, with differences between α→β and β→α reactions of about 0.4 kcal/mol. For xylose, in the same temperature range, the ΔG#α→β and ΔG#β→α barriers are between 20.7 to 21.5 kcal/mol, with differences between α→β and β→α reactions of about 0.2 kcal/mol. The experimental data are in agreement with those reported in literature, confirming the this new stationary phase using HILIC conditions is a robust platform to measure kinetic and thermodynamic properties of the isomerization reaction. Full article
(This article belongs to the Special Issue Advances in Hydrophilic Interaction Chromatography)
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Article
Expanding the Knowledge Related to Flavors and Fragrances by Means of Three-Dimensional Preparative Gas Chromatography and Molecular Spectroscopy
Separations 2022, 9(8), 202; https://doi.org/10.3390/separations9080202 - 04 Aug 2022
Viewed by 358
Abstract
As universally known, gas chromatography (GC) coupled with mass spectrometry (MS) allows us to acquire spectra that can be searched in specific databases to attain qualitative information on a peak of interest. When not present in databases, structure elucidation is required before including [...] Read more.
As universally known, gas chromatography (GC) coupled with mass spectrometry (MS) allows us to acquire spectra that can be searched in specific databases to attain qualitative information on a peak of interest. When not present in databases, structure elucidation is required before including a new component in a library: from that moment, scientists all around the world will be able to identify the new molecule with analytical confidence after GC-MS analysis. Conversely, if data are not shared in commercial databases, even if a molecule is studied and elucidated, it appears to be unknown or only identifiable on the basis of third-party data taken from the literature, which is a serious limitation. The present paper deals with a case that confirms this assumption. A component of Myrtus communis L. volatile fraction was tentatively identified based on literature data. Despite this, reliable identification could not be achieved due to the lack of a corresponding spectrum in commercial MS databases. Afterwards, the target component was isolated in a reasonable quantity and with a high degree of purity for downstream characterization by spectroscopic techniques. For this purpose, preparative (prep) GC may appear insufficient for the isolation of volatile components from highly complex samples. In this study, a prep-MDGC system was implemented for the isolation of the compound of interest from myrtle oil, consisting of three wide-bore columns of different selectivity coupled by means of Deans switch transfer devices. Based on the NMR and GC-FTIR data acquired, the unknown compound was identified as 2,2,5,5,7,7-hexamethyl-3,7-dihydro-1-benzofuran-4,6(2H,5H)-dione. Noticeably, this is a known molecule, yet its mass spectrum had never been registered into MS databases and thus was not available to the scientific community. Finally, the spectrum was included for the first time in a commercial library, namely the FFNSC 5.0 MS database. The aim of the present study was to highlight the opportunity to make analytical data quickly available in a reliable way by registering them in searchable MS databases to improve the identification means for researchers all over the world. Full article
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Article
Synergistic Effect of NiO-Ga2O2-Graphene Heterostructures on Congo Red Photodegradation in Water
Separations 2022, 9(8), 201; https://doi.org/10.3390/separations9080201 - 02 Aug 2022
Viewed by 319
Abstract
We studied the effect of the mixed phase of nickel oxide–gallium oxide–graphene (NiO-Ga2O2/G) heterostructure nanocomposite on the photocatalytic degradation of Congo red dye. The effect was investigated based on NiO-Ga2O2 junction, NiO-graphene, and Ga2O [...] Read more.
We studied the effect of the mixed phase of nickel oxide–gallium oxide–graphene (NiO-Ga2O2/G) heterostructure nanocomposite on the photocatalytic degradation of Congo red dye. The effect was investigated based on NiO-Ga2O2 junction, NiO-graphene, and Ga2O2-graphene contacts. The laser-induced graphene was embedded into NiO and NiO-Ga2O2. Raman spectra confirmed the fabrication of disordered graphene and the mixed phase between the oxides and graphene. HRTEM showed that very fine nanoparticles for both NiO and Ga2O2 with a size of ~7–10 nm were synthesized. Elemental compositional expressed the formation mixed phase. The effect of graphene content was investigated at 2 and 10% wt with NiO and the heterojunction of NiO-Ga2O2. The photocurrent studies was measured of these nanocomposite film deposited on two interdigitated gold electrodes, biased by 5.0 V and irradiated by the UV source. The results of photocatalysis measurements indicated an improvement occurred upon the heterojunction between Ga2O2 and NiO, however, a dramatic improvement was observed with the addition of graphene of 10%. The results expressed that the ternary phase of p-NiO/n-Ga2O2/graphene is promising in the photocatalytic application toward Congo red decomposition. Full article
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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
Viewed by 375
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
Using Solid-Phase Microextraction Coupled with Reactive Carbon Fiber Ionization-Mass Spectrometry for the Detection of Aflatoxin B1 from Complex Samples
Separations 2022, 9(8), 199; https://doi.org/10.3390/separations9080199 - 02 Aug 2022
Viewed by 428
Abstract
Aflatoxin B1 (AFB1) is a common mycotoxin present in agricultural and food products. Therefore, rapid screening methods must be developed for AFB1 detection with high sensitivity and good selectivity. In this study, we developed an analytical method based on the combination of solid-phase [...] Read more.
Aflatoxin B1 (AFB1) is a common mycotoxin present in agricultural and food products. Therefore, rapid screening methods must be developed for AFB1 detection with high sensitivity and good selectivity. In this study, we developed an analytical method based on the combination of solid-phase microextraction (SPME) with carbon fiber ionization (CFI)-mass spectrometry (MS) to detect the presence of trace AFB1 from complex samples. A pencil lead (type 2B, length: ~2.5 cm) with a sharp end (diameter: ~150 μm) was used as the SPME fiber and the ionization emitter in CFI-MS analysis. Owing to the graphite structure of the pencil lead, AFB1 can be trapped on the pencil lead through π–π interactions. After adsorbing AFB1, the pencil lead was directly introduced in a pipette tip (length: ~0.7 cm; tip inner diameter: ~0.6 mm), placed close (~1 mm) to the inlet of the mass spectrometer, and applied with a high voltage (−4.5 kV) for in situ AFB1 elution and CFI-MS analysis. A direct electric contact on the SPME-CFI setup was not required. Followed by the introduction of an elution solvent (10 μL) (acetonitrile/ethanol/deionized water, 2:2:1 (v/v/v)) to the pipette tip, electrospray ionization was generated from the elution solvent containing AFB1 for CFI-MS analysis. A reactive SPME-CFI-MS strategy was employed to further identify AFB1 and improve elution capacity using our approach. Butylamine was added to the elution solvent, which was then introduced to the pipette tip inserted with the SPME fiber. Butylamine-derivatized AFB1 was readily generated and appeared in the resultant SPME-CFI mass spectrum. The lowest detectable concentration against AFB1 using our approach was ~1.25 nM. Our method can distinguish AFB1 from AFG1 in a mixture and can be used for the detection of trace AFB1 in complex peanut extract samples. Full article
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