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Separations, Volume 8, Issue 10 (October 2021) – 33 articles

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Article
Vortex-Assisted Dispersive Molecularly Imprinted Polymer-Based Solid Phase Extraction of Acetaminophen from Water Samples Prior to HPLC-DAD Determination
Separations 2021, 8(10), 194; https://doi.org/10.3390/separations8100194 - 19 Oct 2021
Viewed by 129
Abstract
In the present study, acetaminophen (ACT) molecularly imprinted polymer (ACT-MIP) were successfully synthesized via surface imprinting polymerization. The structural and morphological properties of ACT-MIP were characterized using various analytical techniques. ACT-MIP were used as an adsorbent in a vortex-assisted dispersive molecularly imprinted solid-phase [...] Read more.
In the present study, acetaminophen (ACT) molecularly imprinted polymer (ACT-MIP) were successfully synthesized via surface imprinting polymerization. The structural and morphological properties of ACT-MIP were characterized using various analytical techniques. ACT-MIP were used as an adsorbent in a vortex-assisted dispersive molecularly imprinted solid-phase micro-extraction (VA-d-μ-MISPE), coupled with a high-performance liquid chromatography–diode array detector (HPLC-DAD) method for the determination of ACT in water samples. Influential parameters such as the mass of adsorbent, vortex speed, extraction time, desorption volume, and desorption time were optimized using a multivariate approach. Under optimum conditions, the maximum binding capacities of ACT-MIP and NIP (non-imprinted polymers) were 191 mg/g and 71.5 mg/g, respectively. The linearity was attained across concentrations ranging from 0.630 to 500 µg/L, with a coefficient of determination of 0.9959. For ACT-MIP, the limit of detection (LOD) and limit of quantification (LOQ), enhancement factor, and precision of the method were 0.19 ng/L, 0.63 ng/L, 79, and <5%, respectively. The method was applied in the analysis of spiked water samples, and satisfactory percentage recoveries in the range of 95.3–99.8% were obtained. Full article
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Article
Identification of Deposited Oil Structures on Thin Porous Oil Mist Filter Media Applying µ-CT Imaging Technique
Separations 2021, 8(10), 193; https://doi.org/10.3390/separations8100193 - 19 Oct 2021
Viewed by 144
Abstract
The identification of microscale oil structures formed from deposited oil droplets on the filter front face of a coalescence filter medium is essential to understand the initial state of the coalescence filtration process. Using µ-CT imaging and a deep learning tool for segmentation, [...] Read more.
The identification of microscale oil structures formed from deposited oil droplets on the filter front face of a coalescence filter medium is essential to understand the initial state of the coalescence filtration process. Using µ-CT imaging and a deep learning tool for segmentation, this work presents a novel approach to visualize and identify deposited oil structures as oil droplets on fibers or oil sails between adjacent fibers of different sizes, shapes and orientations. Furthermore, the local and global porosity, saturation and fiber ratios of different fiber material of the oleophilic filter medium was compared and evaluated. Especially the local and global porosity of the filter material showed great accordance. Local and global saturation as well as the fiber ratios on local and global scale had noticeable differences which can mainly be attributed to the small field of view of the µ-CT scan (350 µm on 250 µm) or the minimal resolution of approximately 1 µm. Finally, fiber diameters of the investigated filter material were analyzed, showing a good agreement with the manufacturer’s specifications. The analytical approach to visualize and analyze the deposited oil structures was the main emphasis of this work. Full article
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Review
Recent Advances on the Development of Chemosensors for the Detection of Mercury Toxicity: A Review
Separations 2021, 8(10), 192; https://doi.org/10.3390/separations8100192 - 18 Oct 2021
Viewed by 243
Abstract
The harmful impact of mercury on biological systems is of great concern. Regardless of the efforts made by the regulating agencies, a decrease in Hg2+ concentration has not been realized, and hence mercury accumulation in the environment remains of utmost concern. Designing [...] Read more.
The harmful impact of mercury on biological systems is of great concern. Regardless of the efforts made by the regulating agencies, a decrease in Hg2+ concentration has not been realized, and hence mercury accumulation in the environment remains of utmost concern. Designing novel and efficient probes for recognition and detection of toxic metals in environmental samples has been of primary importance. Among the available techniques, probe designs involving the study of spectral properties has been preferred because of its obvious ease of instrumentation. Furthermore, occurrence of significant changes in the visible portion of electronic spectra enables detection by the naked eye, thereby endorsing the preference for development of probes with off-on binary responses to aid in the in-field sample analysis. The prominence is further streamlined to the use of fluorescence to help characterize on-response the cellular detection of Hg2+ with ease. In order to overcome the problem of developing efficient probes or sensors bearing fluorescence on-response mechanism that can work effectively in physiological conditions, various methodologies, such as chemo-dosimetric reaction mechanisms for the designing of new luminescent ligands, are being adopted. Additionally, modified charge transfer processes are also being considered for optical detection of the mercury (II) ion. In this review, all such possible techniques have been discussed in detail. Full article
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Article
Comparison between Mid-Infrared (ATR-FTIR) Spectroscopy and Official Analysis Methods for Determination of the Concentrations of Alcohol, SO2, and Total Acids in Wine
Separations 2021, 8(10), 191; https://doi.org/10.3390/separations8100191 - 17 Oct 2021
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Abstract
The determination of alcohol, SO2, and total acids in wine through conventional laboratory techniques have some limitations related to the amount of the samples, analytical preparation of laboratory staff, and time to carry out the analysis. In recent years, spectroscopic and [...] Read more.
The determination of alcohol, SO2, and total acids in wine through conventional laboratory techniques have some limitations related to the amount of the samples, analytical preparation of laboratory staff, and time to carry out the analysis. In recent years, spectroscopic and chromatographic methods have been proposed to determinate simultaneously multiple analytical parameters. The new methods claim the speed of analysis and easy execution. However, they need a validation process that guarantees the reliability of the results to be used in official determinations. This study aimed to evaluate the usefulness of FT-infrared reflectance (FT-IR) to quantify total acid, alcohol, and SO2 concentration in the wines. For this purpose, 156 DOC Italian wines were tested with IR technology, and results were compared to those obtained by official analysis methods. The comparison was performed using two non-parametric statistical methods: the Bland & Altman test and Passing & Bablok regression. Our results showed that the spectrophotometric methods make errors due to interfering contaminants in the sample that can be corrected by blank determination. Therefore, the spectrophotometric methods that use the infrared region of the electromagnetic spectrum can be used by the wine industry and regulators for the wine routine as an alternative to official methodologies. Full article
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Article
Separation and Disinfection of Contagious Aerosols from the Perspective of SARS-CoV-2
Separations 2021, 8(10), 190; https://doi.org/10.3390/separations8100190 - 15 Oct 2021
Viewed by 80
Abstract
An assessment was performed on methods of separating and disinfecting airborne droplet nuclei containing viruses, such as SARS-CoV-2. The droplet nuclei originate from evaporating aerosols emitted by the coughing, singing, sneezing, etc. of infected humans. Based on empirical data and theoretical analysis, we [...] Read more.
An assessment was performed on methods of separating and disinfecting airborne droplet nuclei containing viruses, such as SARS-CoV-2. The droplet nuclei originate from evaporating aerosols emitted by the coughing, singing, sneezing, etc. of infected humans. Based on empirical data and theoretical analysis, we successively determined: (i) the particle number distribution of nuclei versus the nucleus diameter, (ii) the statistical distribution of the viral content in the droplet nuclei starting from a uniform random distribution of viruses in the mucus, (iii) the particle number distribution of droplet nuclei containing at least one virus particle, and (iv) the effectiveness of methods for removing and disinfecting nuclei containing one or more virus particles from indoor air; viz., ventilation with fresh air, filtering with porous media, such as HEPA, and centrifugal separation and simultaneous disinfection, particularly with a rotational particle separator (RPS). Indoor aerosol removal with RPS supplemented with HEPA to arrest tiny volumes of very small particles was found to be the most effective. It is as good as particle removal through ventilation with clean air over long periods of time. An RPS facilitates direct elimination of viruses in the collected nuclei by flushing with a disinfection liquid. The components of an RPS are recyclable. Combining HEPA with an RPS extends the service time of HEPA by almost two orders of magnitude compared to the relatively short service time of stand-alone HEPA filters. Full article
(This article belongs to the Collection State-of-Art in Separation Science)
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Article
Validation and Clinical Application of a New Liquid Chromatography Coupled to Mass Spectrometry (HPLC-MS) Method for Dalbavancin Quantification in Human Plasma
Separations 2021, 8(10), 189; https://doi.org/10.3390/separations8100189 - 15 Oct 2021
Viewed by 47
Abstract
Dalbavancin (DBV) is an intravenous long-acting second-generation glycolipopeptide antibiotic with high efficacy and excellent tolerability, approved for use in the treatment of Gram-positive skin and skin structure infections (ABSSSI). Nevertheless, little is known about its pharmacokinetic/pharmacodynamic (PK/PD) properties in real life, which is [...] Read more.
Dalbavancin (DBV) is an intravenous long-acting second-generation glycolipopeptide antibiotic with high efficacy and excellent tolerability, approved for use in the treatment of Gram-positive skin and skin structure infections (ABSSSI). Nevertheless, little is known about its pharmacokinetic/pharmacodynamic (PK/PD) properties in real life, which is also due to technical challenges in its quantification in human plasma, preventing an effective application of therapeutic drug monitoring (TDM). In fact, DBV has a high affinity to plasma proteins, possibly resulting in poor recovery after extraction procedure. The aim of this study was to validate a simple, cheap and reliable HPLC-MS method for use in TDM, in accordance with FDA and EMA guidelines. The optimized protein precipitation protocol required 50 μL of plasma, while chromatographic analysis could be performed in 12 min/sample. This method fulfilled the guidelines requirements and then, it was applied for routine DBV TDM in patients receiving off-label high doses (two 1500 + 1500 mg weekly infusions instead of 1000 + 500 mg), with normal renal function or undergoing hemodialysis: continuous hemodiafiltration caused a relevant reduction in DBV exposure, while intermittent dialysis showed comparable DBV concentrations with those of patients with normal renal function. This confirmed the eligibility of the presented method for use in TDM and its usefulness in clinical practice. Full article
(This article belongs to the Special Issue Chromatographic Methods in Therapeutic Drug Monitoring (TDM))
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Article
Plasma Short-Chain Fatty Acids and Their Derivatives in Women with Gestational Diabetes Mellitus
Separations 2021, 8(10), 188; https://doi.org/10.3390/separations8100188 - 14 Oct 2021
Viewed by 318
Abstract
Gestational diabetes mellitus (GDM) represents a heterogeneous group of hyperglycemic metabolic disorders that are associated with health outcomes for mothers and offspring. Currently, diagnosis of GDM is based on repetitive measurement of increased fasting plasma glucose (FPG) or upon results showing increased postprandial [...] Read more.
Gestational diabetes mellitus (GDM) represents a heterogeneous group of hyperglycemic metabolic disorders that are associated with health outcomes for mothers and offspring. Currently, diagnosis of GDM is based on repetitive measurement of increased fasting plasma glucose (FPG) or upon results showing increased postprandial plasma glucose (PPG). Recently, it was discovered that the changes in the gut microbiome during pregnancy are associated with insulin resistance and obesity. Therefore, in this study, relevant products of gut bacteria, short-chain fatty acids (SCFA) and their derivatives were evaluated together with baseline body composition characteristics and common biochemical parameters in women with three different phenotypes of GDM, healthy pregnant and nonpregnant women. Plasma SCFA and their derivatives were derivatized, separated on reversed-phase liquid chromatography and detected by a triple-quadrupole mass spectrometer. 3-hydroxybutyrate (3-OH-BA), 4-methylvalerate (4-MVA) and isovalerate (IVA), together with selected parameters associated with baseline body composition characteristics and biochemistry, were evaluated as statistically significant. 3-OH-BA, which was increased in all three groups of women with different phenotypes of GDM, reflects a ketogenic state of GDM. In all groups of pregnant women, elevated/suppressed concentrations of 4-MVA/IVA were found. These findings show the importance of monitoring SCFA and other parameters besides glucose in women with GDM. Full article
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Article
Role of Extracts Obtained from Rainbow Trout and Sole Side Streams by Accelerated Solvent Extraction and Pulsed Electric Fields on Modulating Bacterial and Anti-Inflammatory Activities
Separations 2021, 8(10), 187; https://doi.org/10.3390/separations8100187 - 14 Oct 2021
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Abstract
In this study, accelerated solvent extraction (ASE) and pulsed electric field (PEF) were used as innovative approaches to recover extracts from rainbow trout and sole side streams rich in high-added-value compounds. Then, after aseptic filtration, the impact of the obtained extracts on bacterial [...] Read more.
In this study, accelerated solvent extraction (ASE) and pulsed electric field (PEF) were used as innovative approaches to recover extracts from rainbow trout and sole side streams rich in high-added-value compounds. Then, after aseptic filtration, the impact of the obtained extracts on bacterial growth and anti-inflammatory potential was evaluated. Moreover, the protein content and the total antioxidant capacity of the samples were determined. The results showed that some extracts could inhibit the growth of pathogenic bacteria, including the ASE rainbow trout skin and the PEF sole viscera extracts, which showed significant antibacterial activity on Staphylococcus aureus. The PEF sole viscera extract also showed an inhibitory effect on the growth of Salmonella. In addition, some extracts promoted probiotic bacteria growth. For example, the PEF rainbow trout head and skin extracts promoted Lactobacillus casei growth, while the ASE rainbow trout head and skin extracts promoted Bifidobacterium lactis growth. In addition, some samples, such as the ASE rainbow trout viscera and the PEF sole skin extracts had interesting anti-inflammatory properties. Therefore, the use of ASE and PEF can be considered as useful strategies to recover antimicrobial, prebiotic and anti-inflammatory extracts from rainbow trout and sole side streams, although it is necessary to evaluate each specific side stream. Full article
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Article
The Separation and Purification of Ellagic Acid from Phyllanthus urinaria L. by a Combined Mechanochemical-Macroporous Resin Adsorption Method
Separations 2021, 8(10), 186; https://doi.org/10.3390/separations8100186 - 14 Oct 2021
Viewed by 130
Abstract
Ellagic acid is a phenolic compound that exhibits both antimutagenic and anticarcinogenic activity in a wide range of assays in vitro and in vivo. It occurs naturally in some foods such as raspberries, strawberries, grapes, and black currants. In this study, a valid [...] Read more.
Ellagic acid is a phenolic compound that exhibits both antimutagenic and anticarcinogenic activity in a wide range of assays in vitro and in vivo. It occurs naturally in some foods such as raspberries, strawberries, grapes, and black currants. In this study, a valid and reliable method based on mechanochemical-assisted extraction (MCAE) and macroporous adsorption resin was developed to extract and prepare ellagic acid from Phyllanthus urinaria L. (PUL). The MCAE parameters, acidolysis, and macroporous adsorption resin conditions were investigated. The key MCAE parameters were optimized as follows: the milling time was 5 min, the ball mill speed was 100 rpm, and the ball mill filling rate was 20.9%. Sulfuric acid with a concentration of 0.552 mol/L was applied for the acidolysis with the optimized acidolysis time of 30 min and acidolysis temperature of 40 °C. Additionally, the XDA-8D macroporous resin was chosen for the purification work. Both the static and dynamic adsorption tests were carried out. Under the optimized conditions, the yield of ellagic acid was 10.2 mg/g, and the content was over 97%. This research provided a rapid and efficient method for the preparation of ellagic acid from the cheaply and easily obtained PUL. Meanwhile, it is relatively low-cost work that can provide a technical basis for the comprehensive utilization of PUL. Full article
(This article belongs to the Special Issue Preparation and Quality Control of Natural Products)
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Article
Studies on the Separation and Purification of the Caulis sinomenii Extract Solution Using Microfiltration and Ultrafiltration
Separations 2021, 8(10), 185; https://doi.org/10.3390/separations8100185 - 14 Oct 2021
Viewed by 186
Abstract
The separation and purification process of alkaloids faces great challenges of pollution, high energy consumption and low continuity. In this study, the effects of ceramic microfiltration (MF) membrane (membrane pore size of 0.50 μm, 0.20 μm, 0.05 μm) and organic ultrafiltration (UF) membrane [...] Read more.
The separation and purification process of alkaloids faces great challenges of pollution, high energy consumption and low continuity. In this study, the effects of ceramic microfiltration (MF) membrane (membrane pore size of 0.50 μm, 0.20 μm, 0.05 μm) and organic ultrafiltration (UF) membrane (membrane molecular weight cut-off of 10 KDa and 1 KDa) on the separation and purification of Caulis sinomenii extract solution in pilot scale were studied. The cleaning effects of different cleaning methods (pure water, 1% HCl-NaOH, 1% sodium hypochlorite) were investigated. The experimental results indicated that 0.05 μm ceramic membrane and 1 kDa UF membrane have higher sinomenine hydrochloride (SH) permeabilities and total solids (TS) removal rates. The ceramic membrane was circulating cleaned by 1% sodium hypochlorite solution for 1 h; the membrane flux can be restored to more than 90% of the original, the membrane flux of 1 kDa UF membrane can be restored to 99.2% of the original by pure water washing. From the above study, the optimal technic parameters was determined in which 0.05 μm ceramic MF membrane and 1 kDa UF membrane were used to separate and purify the Caulis sinomenii extract solution to remove the invalid ingredients, and the two kinds of membranes were cleaned with 1% sodium hypochlorite solution and pure water, respectively, to keep satisfactory membrane fluxes. The study provided an environment-friendly alternative for the separation and purification of alkaloids in natural products, which has a good prospect for the industrial application. Full article
(This article belongs to the Special Issue Preparation and Quality Control of Natural Products)
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Article
Rapid, Highly-Sensitive and Ecologically Greener Reversed-Phase/Normal-Phase HPTLC Technique with Univariate Calibration for the Determination of Trans-Resveratrol
Separations 2021, 8(10), 184; https://doi.org/10.3390/separations8100184 - 12 Oct 2021
Viewed by 202
Abstract
The rapid, highly-sensitive and ecologically greener reversed-phase (RP)/normal-phase (NP) high-performance thin-layer chromatography (HPTLC) densitometric technique has been developed and validated for the determination of trans-resveratrol (TRV). The reversed-phase HPTLC-based analysis of TRV was performed using ethanol–water (65:35, v v−1) combination [...] Read more.
The rapid, highly-sensitive and ecologically greener reversed-phase (RP)/normal-phase (NP) high-performance thin-layer chromatography (HPTLC) densitometric technique has been developed and validated for the determination of trans-resveratrol (TRV). The reversed-phase HPTLC-based analysis of TRV was performed using ethanol–water (65:35, v v−1) combination as the greener mobile phase, while, the normal-phase HPTLC-based estimation of TRV was performed using chloroform–methanol (85:15, v v−1) combination as the routine mobile phase. The TRV detection was carried out at 302 nm for RP/NP densitometric assay. The linearity was recorded as 10–1200 and 30–400 ng band−1 for RP and NP HPTLC techniques, respectively. The RP densitometric assay was observed as highly-sensitive, accurate, precise and robust for TRV detection in comparison with the NP densitometric assay. The contents of TRV in commercial formulation were recorded as 101.21% utilizing the RP densitometric assay, while, the contents of TRV in commercial formulation were found to be 91.64% utilizing the NP densitometric assay. The greener profile of RP/NP technique was obtained using the analytical GREEnness (AGREE) approach. The AGREE scales for RP and NP densitometric assays were estimated 0.75 and 0.48, respectively. The recorded AGREE scale for the RP densitometric assay indicated that this technique was highly green/the ecologically greener compared to the NP densitometric assay. After successful optimization of analytical conditions, validation parameters, AGREE scale and chromatography performance, the RP densitometric assay with univariate calibration was found to be better than the NP densitometric assay for the analysis of TRV. Full article
(This article belongs to the Special Issue Chemical Analysis of Bioactive Compounds in Food)
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Review
Hemp Growth Factors and Extraction Methods Effect on Antimicrobial Activity of Hemp Seed Oil: A Systematic Review
Separations 2021, 8(10), 183; https://doi.org/10.3390/separations8100183 - 12 Oct 2021
Viewed by 276
Abstract
The bioactive Hemp Seed Oil (HSO) is becoming very popular in the medical and research fields due to its antimicrobial properties against several diseases caused by bacteria and fungi. However, the effect of hemp-growing factors and extraction methods on the bioactivity of HSO [...] Read more.
The bioactive Hemp Seed Oil (HSO) is becoming very popular in the medical and research fields due to its antimicrobial properties against several diseases caused by bacteria and fungi. However, the effect of hemp-growing factors and extraction methods on the bioactivity of HSO does not receive adequate research attention. Therefore, this review aims to investigate the effect of growth factors and extraction methods on the antimicrobial activity of HSO. Articles were retrieved from Google Scholar and the Scopus database and screened against inclusion and exclusion criteria. The study revealed that HSO prefers warm climates and favorable humidity ranging from 20 to 39 °C and 79–100% per year, respectively, and rainfall of 324 mm daily. The multivariate linear regression shown excellent prediction (R2 = 0.94) with climates upon Zone of Growth Inhibition (ZGI) of Gram-positive bacteria. Temperature is the strongest predictor (p < 0.01) followed by humidity and rainfall (p < 0.05). Furthermore, well-drained loam soil rich in organic matter seems to stimulate the antimicrobial activity of HSO. The major constituents that influence HSO’s antimicrobial ability to Staphylococcus aureus were cannabidiol (CBD), β-caryophyllene, and limonene. The extraction methods showed less influence on the HSO bioactivity. HSO did not show significant antioxidant activity, but Hemp Seed Hull (HSH), Hemp Seed Flour (HSF), and Hydrolyzed Hemp Seed Protein (HPH), expressed promising DPPH scavenging ability. Full article
(This article belongs to the Special Issue Separations and Analysis of Proteins in Biological Samples)
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Article
Geochemical Analysis of Two Samples of Bitumen from Jars Discovered on Muhut and Masirah Islands (Oman)
Separations 2021, 8(10), 182; https://doi.org/10.3390/separations8100182 - 12 Oct 2021
Viewed by 306
Abstract
Two samples of bitumen were obtained, one from a torpedo jar (c. 3rd–8th C. AD) from Masirah island and one from a Tunisian jar (c. 18th C. AD) from Muhut island off the central coast of Oman. Steranes and terpanes, as well as [...] Read more.
Two samples of bitumen were obtained, one from a torpedo jar (c. 3rd–8th C. AD) from Masirah island and one from a Tunisian jar (c. 18th C. AD) from Muhut island off the central coast of Oman. Steranes and terpanes, as well as isotope data on chromatographic fractions, were used as tools to characterize the bitumen. Comparison of data with those already acquired on bitumen from torpedo jars from Thailand, Iran, Indonesia, Sri Lanka, Saudi Arabia, India, and oil seeps from Iran and Iraq allowed us to conclude that the bitumen originated from different areas of southwest Iran. Those of the Muhut jar were likely from Khuzistan, whereas those from Masirah island appear to have been sourced from Kermanshah. These findings are in keeping with other similar geochemical studies undertaken on bitumen lined vessels from across the region (see more below). Full article
(This article belongs to the Special Issue Analytical Chromatography Applied to Archaeology)
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Article
An Index for Quantitative Evaluation of the Mixing in Ethanol Precipitation of Traditional Chinese Medicine
Separations 2021, 8(10), 181; https://doi.org/10.3390/separations8100181 - 12 Oct 2021
Viewed by 174
Abstract
(1) Background: Ethanol precipitation is widely used in the manufacturing traditional Chinese medicines (TCMs). Insufficient mixing of ethanol solution and concentrate usually results in the coating loss of active ingredients. However, there is no index for quantitative evaluation of the mixing in ethanol [...] Read more.
(1) Background: Ethanol precipitation is widely used in the manufacturing traditional Chinese medicines (TCMs). Insufficient mixing of ethanol solution and concentrate usually results in the coating loss of active ingredients. However, there is no index for quantitative evaluation of the mixing in ethanol precipitation. Therefore, this study aimed to define an index for quantitative evaluation of the mixing effect in ethanol precipitation of TCMs. (2) Methods: The concept and requirements of a mixing indicator were proposed. The mass percentage of concentrate fully mixed with ethanol solution (well-mixing ratio, WMR) was used as an index to evaluate the mixing effect. The formula for calculation of WMR was derived. The utility of the WMR was evaluated on stirring devices and a micromesh mixer. (3) Results: Increasing stirring speed, decreasing total solid content of the concentrate, and decreasing the diameter of the ethanol solution droplets all resulted in higher retention rates for lobetyolin and higher WMR. The WMR increased with the increasing flow rate of the concentrate and ethanol solution in the micromesh mixer. The mixing of ethanol solution and concentrate was better when using a micromesh mixer with a smaller internal mixing zone. The results revealed that WMR could be used to quantitatively characterize the mixing of concentrate and ethanol solution, although it has some limitations. (4) Conclusions: The proposed index WMR could guide quality control of the TCM ethanol precipitation process. This study represents a new contribution to improving ethanol precipitation equipment, optimizing process parameters, and enhanced properties of concentrate for TCM enterprises. Full article
(This article belongs to the Special Issue Preparation and Quality Control of Natural Products)
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Article
1,2-Propylene Glycol: A Biomarker of Exposure Specific to e-Cigarette Consumption
Separations 2021, 8(10), 180; https://doi.org/10.3390/separations8100180 - 09 Oct 2021
Viewed by 300
Abstract
Over the past decade, new emerging tobacco and nicotine-delivery products have changed the tobacco landscape. Especially, electronic cigarettes (ECs) have been suggested to be considered for tobacco harm reduction, reinforcing the need to identify novel biomarkers of exposure (BoE) specific to the EC [...] Read more.
Over the past decade, new emerging tobacco and nicotine-delivery products have changed the tobacco landscape. Especially, electronic cigarettes (ECs) have been suggested to be considered for tobacco harm reduction, reinforcing the need to identify novel biomarkers of exposure (BoE) specific to the EC use as this would complement exposure assessment and product compliance monitoring. Therefore, a sensitive LC-MS/MS method for the quantification of 1,2-propylene glycol (PG) and glycerol (G), the main e-liquid constituents, was established. PG and G were analyzed in plasma and urine samples from a clinical study comparing five nicotine product user groups, users of combustible cigarettes (CC), electronic cigarettes (EC), heated tobacco products (HTP), oral tobacco (OT), and oral/dermal nicotine delivery products (used for nicotine replacement therapy, NRT) with a control group of non-users (NU). Data demonstrate significantly elevated PG levels in urine and plasma in EC users compared to users of CC, HTP, NRT, OT as well as NU. In addition, PG in plasma and urine of vapers significantly correlated with nicotine (plasma) and total nicotine equivalents (urine), biomarkers reflecting product consumption, emphasizing the high specificity of PG as a BoE for EC consumption. We therefore suggest the use of PG as BoE in urine and/or plasma in order to monitor EC use compliance in exposure assessments. Full article
(This article belongs to the Special Issue Method Development and Applications for Reduced-Risk Products)
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Article
Study on the Stability of Antibiotics, Pesticides and Drugs in Water by Using a Straightforward Procedure Applying HPLC-Mass Spectrometric Determination for Analytical Purposes
Separations 2021, 8(10), 179; https://doi.org/10.3390/separations8100179 - 09 Oct 2021
Viewed by 195
Abstract
The stability of analytes is a critical point in chemical analysis, especially in the field of trace levels residue analysis. Nowadays, due to advances in analytical technology and in separation sciences, the analyses of water have been improved. Unfortunately, in this context, one [...] Read more.
The stability of analytes is a critical point in chemical analysis, especially in the field of trace levels residue analysis. Nowadays, due to advances in analytical technology and in separation sciences, the analyses of water have been improved. Unfortunately, in this context, one of the most critical issues in water analysis include compound stability from sampling station to laboratory procedures. This study was carried out to explore the stability of several compounds in water from sampling to analysis concerning analytes reported in implementing decision 2018/840—Watch List. During method development and validation, the stability of compounds was investigated to detect the best operating conditions concerning sampling, extraction and analysis. In this paper, we report a study on the stability of antibiotics, pesticides and drugs in water determined using a straight-forward procedure applying mass spectrometric detection for analytical purposes. The laboratory tests were performed in Milli-Q water and surface water by analyzing samples through direct injection, solvent mixture (Water/ACN) and solid phase extraction system from time 0 to 168 h. All the analytes of the WL are stable in aqueous solutions with the addition of at least 25% ACN even after 168 h, and the analytes have shown a matrix effect on recovery of some analytes such as Famoxadone from sampling results (recovery in surface water 72%). For all the analytes investigated, recoveries were between 70 and 130% by using SPE procedures before UHPLC-MS/MS analysis, which is in good agreement with method validation procedures. Full article
(This article belongs to the Special Issue HPLC: A Key Tool for Analytical Chemistry)
Article
Iterative Multivariate Peaks Fitting—A Robust Approach for The Analysis of Non-Baseline Resolved Chromatographic Peaks
Separations 2021, 8(10), 178; https://doi.org/10.3390/separations8100178 - 08 Oct 2021
Viewed by 239
Abstract
Selectivity in separation science is defined as the extent to which a method can determine the target analyte free of interference. It is the backbone of any method and can be enhanced at various steps, including sample preparation, separation optimization and detection. Significant [...] Read more.
Selectivity in separation science is defined as the extent to which a method can determine the target analyte free of interference. It is the backbone of any method and can be enhanced at various steps, including sample preparation, separation optimization and detection. Significant improvement in selectivity can also be achieved in the data analysis step with the mathematical treatment of the signals. In this manuscript, we present a new approach that uses mathematical functions to model chromatographic peaks. However, unlike classical peak fitting approaches where the fitting parameters are optimized with a single profile (one-way data), the parameters are optimized over multiple profiles (two-way data). Thus, it allows high confidence and robustness. Furthermore, an iterative approach where the number of peaks is increased at each step until convergence is developed in this manuscript. It is demonstrated with simulated and real data that this algorithm is: (1) capable of mathematically separating each component with minimal user input and (2) that the peak areas can be accurately measured even with resolution as low as 0.5 if the peak’s intensities does not differ by more than a factor 10. This was conclusively demonstrated with the quantification of diterpene esters in standard mixtures. Full article
(This article belongs to the Special Issue Computer-Aided Separation Analysis)
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Article
Chemical and Antioxidant Characterization of the Portuguese Heather Honey from Calluna vulgaris
Separations 2021, 8(10), 177; https://doi.org/10.3390/separations8100177 - 08 Oct 2021
Viewed by 215
Abstract
The Calluna vulgaris honey produced in Portugal, concerning its phenolic compounds and abscisic acids profiles, as well as its antioxidant activity and the protective effect against oxidative damage in human erythrocytes were herein performed for the first time. The phenolic and abscisic acid [...] Read more.
The Calluna vulgaris honey produced in Portugal, concerning its phenolic compounds and abscisic acids profiles, as well as its antioxidant activity and the protective effect against oxidative damage in human erythrocytes were herein performed for the first time. The phenolic and abscisic acid profiles were tentatively identified by LC-MS/MS (17 compounds). The total content of phenolics and abscisic acids was 15,446.4 µg/g of honey extract, with catechin derivatives and abscisic acids being major constituents. The highest scavenging capacity was found against reactive nitrogen species. Additionally, the honey extract prevented ROO-induced oxidative damage in erythrocytes collected from human blood, by inhibiting hemolysis, lipid peroxidation and hemoglobin oxidation. In conclusion, C. vulgaris honey contains high content of catechin derivatives and abscisic acids that may be responsible for its biological activity, characterized by a strong antioxidant capacity, which adds up to the nutritional value of this delicacy. Full article
(This article belongs to the Special Issue Chemical Analysis of Bioactive Compounds in Food)
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Review
Deep Eutectic Solvents (DESs) as Green Extraction Media of Beneficial Bioactive Phytochemicals
Separations 2021, 8(10), 176; https://doi.org/10.3390/separations8100176 - 07 Oct 2021
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Abstract
Deep eutectic solvents (DES) are a mixture of two or more components and are classified as ionic solvents with special properties such as low volatility, high solubility, low melting points, low-cost materials and are less toxic to humans. Using DES has been suggested [...] Read more.
Deep eutectic solvents (DES) are a mixture of two or more components and are classified as ionic solvents with special properties such as low volatility, high solubility, low melting points, low-cost materials and are less toxic to humans. Using DES has been suggested as an eco-friendly, green method for extraction of bioactive compounds from medicinal plants and are a safe alternative for nutritional, pharmaceutical and various sector applications. Conventional solvent extraction methods present drawbacks such as long extraction period, safety issues, harmful to the environment, costly and large volume of solvents required. The extraction method with DES leads to higher extraction yield and better bioactivity results as compared to the conventional solvents. This review provides a summary of research progress regarding the advantages of using DES to extract bioactive compounds such as phenolic acid, flavonoids, isoflavones, catechins, polysaccharides, curcuminoids, proanthocyanidin, phycocyanin, gingerols, ginsenosides, anthocyanin, xanthone, volatile monoterpenes, tannins, lignin, pectin, rutin, tert-butyl hydroquinone, chlorogenic acids, resveratrol and others, as opposed to using conventional solvents. The bioactivity of the extracts is determined using antioxidant, antibacterial and antitumor activities. Hence, DESs are considered potential green media with selective and efficient properties for extracting bioactive ingredients from medicinal plants. Full article
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Article
Phytochemical Responses to Salt Stress in Red and Green Baby Leaf Lettuce (Lactuca sativa L.) Varieties Grown in a Floating Hydroponic Module
Separations 2021, 8(10), 175; https://doi.org/10.3390/separations8100175 - 07 Oct 2021
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Abstract
Lettuce (Lactuca sativa L.) is one of the most popular leafy vegetables, appreciated globally as a low-calorie food with bioactive compounds. The application of a low dose of abiotic stress is considered a sustainable pre-harvest strategy to modify the nutraceutical value of [...] Read more.
Lettuce (Lactuca sativa L.) is one of the most popular leafy vegetables, appreciated globally as a low-calorie food with bioactive compounds. The application of a low dose of abiotic stress is considered a sustainable pre-harvest strategy to modify the nutraceutical value of horticultural products. In this work, we explored the response of two differently colored (red or green) baby leaf lettuce varieties to four NaCl concentrations in the nutrient solution (from 1 to 30 mM), using a full factorial design. We focused on leaf morphological parameters and possible phytochemical enhancement of the main polyphenols and anthocyanins, analyzed by LC-MS. The response to low-to-moderate salt stress exposure was affected mainly by salt concentration for leaf traits or by the cultivar for leaf color, with very limited factors’ interactions. Multivariate analysis indicated a predominant role of the genotypic factor in shaping differences in the two weeks growing cycle for baby leaf lettuce. Phytochemically, different dose–response models to sub-optimal saline conditions may be applied to the various compounds. A significant hormetic stimulation was present only for cyanidin-malonyl glucoside, the main anthocyanin present in the red cultivar. Full article
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Article
Nutritional Value of Sea Urchin Roe (Strongylocentrotidae)—Study of Composition and Storage Conditions
Separations 2021, 8(10), 174; https://doi.org/10.3390/separations8100174 - 07 Oct 2021
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Abstract
Although the roe of sea urchins inhabiting the Far Eastern seas possesses many healing properties and may be used as a dietary product, a reduction and deterioration in its nutritional quality during storage occurs. Therefore, in order to make sea urchin products widely [...] Read more.
Although the roe of sea urchins inhabiting the Far Eastern seas possesses many healing properties and may be used as a dietary product, a reduction and deterioration in its nutritional quality during storage occurs. Therefore, in order to make sea urchin products widely accessible to the world population, it is very important to have appropriate technology to keep the roe from spoiling. To store sea urchin roe for a long time, methods of pre-processing sea urchin gonads before freezing were tested. In terms of preserving organoleptic properties and nutritional quality, the most adequate procedure consists of a short period (20 or 30 s) of heat (boiling water) treatment of sea urchin roe after removal from the shell. This procedure results in an inactivation of enzymes that catalyze the hydrolytic processes of lipids and proteins during storage. After blanching and cooling, the roe was packed, frozen and kept at a temperature of −18 °C and −25 °C. The quality of sea urchin roe did not change during storage at the temperature of −18 °C for 6 months, and at the temperature of −25 °C for 10 months. Full article
(This article belongs to the Special Issue Separation and Quantitative Analysis of Natural Product Extracts)
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Article
Tyrosol and Hydroxytyrosol Determination in Extra Virgin Olive Oil with Direct Liquid Electron Ionization-Tandem Mass Spectrometry
Separations 2021, 8(10), 173; https://doi.org/10.3390/separations8100173 - 06 Oct 2021
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Abstract
Extra virgin olive oil (EVOO) is one of the main ingredients of the Mediterranean diet. It is claimed as a functional food for its unique content of health-promoting compounds. Tyrosol (Tyr), Hydroxytyrosol (Htyr), and their phenolic derivatives present in EVOO show beneficial properties, [...] Read more.
Extra virgin olive oil (EVOO) is one of the main ingredients of the Mediterranean diet. It is claimed as a functional food for its unique content of health-promoting compounds. Tyrosol (Tyr), Hydroxytyrosol (Htyr), and their phenolic derivatives present in EVOO show beneficial properties, and their identification and quantification, both in their free form and after the hydrolysis of more complex precursors, are important to certify its quality. An alternative method for quantifying free and total Tyr and Htyr in EVOO is presented using an LC–MS interface based on electron ionization (EI), called liquid electron ionization (LEI). This method requires neither sample preparation nor chromatography; the sample is diluted and injected. The selectivity and sensitivity were assessed in multiple reaction monitoring mode (MRM), obtaining confirmation and quantification in actual samples ranging from 5 to 11 mg/Kg for the free forms and from 32 to 80 mg/Kg for their total amount after hydrolysis. Two MS/MS transitions were acquired for both compounds using the Q/q ratios as confirmatory parameters. Standard addition calibration curves demonstrated optimal linearity and negligible matrix effects, allowing a correct quantification even without expensive and difficult to find labeled internal standards. After several weeks of operation, the system’s repeatability was excellent, with an intraday RSD (%) spanning from five to nine and an interday RSD (%) spanning from 9 to 11. Full article
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Article
Designing Safer Solvents to Replace Methylene Chloride for Liquid Chromatography Applications Using Thin-Layer Chromatography as a Screening Tool
Separations 2021, 8(10), 172; https://doi.org/10.3390/separations8100172 - 06 Oct 2021
Viewed by 239
Abstract
Methylene chloride, commonly known as dichloromethane (DCM), is a widely used chemical for chromatography separation within the polymer, chemical, and pharmaceutical industries. With the ability to effectively solvate heterocyclic compounds, and properties including a low boiling point, high density, and low cost, DCM [...] Read more.
Methylene chloride, commonly known as dichloromethane (DCM), is a widely used chemical for chromatography separation within the polymer, chemical, and pharmaceutical industries. With the ability to effectively solvate heterocyclic compounds, and properties including a low boiling point, high density, and low cost, DCM has become the solvent of choice for many different applications. However, DCM has high neurotoxicity and is carcinogenic, with exposure linked to damage to the brain and the central nervous system, even at low exposure levels. This research focuses on sustainability and works towards finding safer alternative solvents to replace DCM in pharmaceutical manufacturing. The research was conducted with three active pharmaceutical ingredients (API) widely used in the pharmaceutical industry: acetaminophen, aspirin, and ibuprofen. Thin-layer chromatography (TLC) was used to investigate if an alternative solvent or solvent blend could show comparable separation performance to DCM. The use of the Hansen Solubility Parameter (HSP) theory and solubility testing allowed for the identification of potential alternative solvents or solvent blends to replace DCM. HSP values for the three APIs were experimentally determined and used to identify safer solvents and blends that could potentially replace DCM. Safer solvents or binary solvent blends were down-selected based on their dissolution power, safety, and price. The down-selected solvents (e.g., ethyl acetate) and solvent blends were further evaluated using three chemical hazard classification approaches to find the best fitting nonhazardous replacement to DCM. Several safer solvent blends (e.g., mixtures composed of methyl acetate and ethyl acetate) with adequate TLC performance were identified. Results from this study are expected to provide guidance for identifying and evaluating safer solvents to separate APIs using chromatography. Full article
(This article belongs to the Special Issue Separations in Biomedical Analysis)
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Article
A Sensitive LC–MS/MS Method for the Quantification of 3-Hydroxybenzo[a]pyrene in Urine-Exposure Assessment in Smokers and Users of Potentially Reduced-Risk Products
Separations 2021, 8(10), 171; https://doi.org/10.3390/separations8100171 - 05 Oct 2021
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Abstract
Benzo[a]pyrene (BaP), a human carcinogen, is formed during the incomplete combustion of organic matter such as tobacco. A suitable biomarker of exposure is the monohydroxylated metabolite 3-hydroxybenzo[a]pyrene (3-OH-BaP). We developed a sensitive LC–MS/MS (liquid chromatography coupled with tandem mass [...] Read more.
Benzo[a]pyrene (BaP), a human carcinogen, is formed during the incomplete combustion of organic matter such as tobacco. A suitable biomarker of exposure is the monohydroxylated metabolite 3-hydroxybenzo[a]pyrene (3-OH-BaP). We developed a sensitive LC–MS/MS (liquid chromatography coupled with tandem mass spectrometry) method for the quantification of urinary 3-OH-BaP. The method was validated according to the US Food and Drug Administration (FDA) guideline for bioanalytical method validation and showed excellent results in terms of accuracy, precision, and sensitivity (lower limit of quantification (LLOQ): 50 pg/L). The method was applied to urine samples derived from a controlled clinical study to compare exposure from cigarette smoking to the use of potentially reduced-risk products. Urinary 3-OH-BaP concentrations were significantly higher in smokers of conventional cigarettes (149 pg/24 h) compared to users of potentially reduced-risk products as well as non-users (99% < LLOQ in these groups). In conclusion, 3-OH-BaP is a suitable biomarker to assess the exposure to BaP in non-occupationally exposed populations and to distinguish not only cigarette smokers from non-smokers but also from users of potentially reduced-risk products. Full article
(This article belongs to the Special Issue Method Development and Applications for Reduced-Risk Products)
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Article
Accurate Determination of Electrical Potential on Ion Exchange Membranes in Reverse Electrodialysis
Separations 2021, 8(10), 170; https://doi.org/10.3390/separations8100170 - 04 Oct 2021
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Abstract
Reverse electrodialysis is a promising membrane technology to generate energy from controlled mixing of water streams of different salinities. Electrical potentials generate on the ion exchange membranes (IEMs) when selective transport of cations and anions across the membranes driven by concentration difference. The [...] Read more.
Reverse electrodialysis is a promising membrane technology to generate energy from controlled mixing of water streams of different salinities. Electrical potentials generate on the ion exchange membranes (IEMs) when selective transport of cations and anions across the membranes driven by concentration difference. The accurate determination of the potentials developed on the IEMs is critical to fairly assess the feasibility of the technology. The Nernst–Planck–Poisson (NPP) equations for IEMs (the membranes with fixed charge) were solved numerically with the boundary updating scheme. The validity of this numerical method was verified by the identical values of Donnan potential obtained with the well-established analytical methods. The suitability and applicability of the classic Teorell–Meyer–Siever (TMS) model were assessed by comparison to the simulation results from the numerical method. Full article
(This article belongs to the Special Issue Modeling, Simulation, and Optimization of Membrane Processes)
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Article
Determination of Metals in Walnut Oils by Means of an Optimized and Validated ICP-AES Method in Conventional and Organic Farming Type Samples
Separations 2021, 8(10), 169; https://doi.org/10.3390/separations8100169 - 03 Oct 2021
Viewed by 343
Abstract
Agricultural products are indispensable for equilibrated diets since they discharge minerals and several bioactive constituents. Considering the increasing demand for organic products, research has been conducted over recent years to investigate whether organically grown food products are chemically different compared to those produced [...] Read more.
Agricultural products are indispensable for equilibrated diets since they discharge minerals and several bioactive constituents. Considering the increasing demand for organic products, research has been conducted over recent years to investigate whether organically grown food products are chemically different compared to those produced with conventional farming. In this work, a novel inductively coupled plasma atomic emission spectrometric method was developed and validated for the determination of nutrient and toxic elements in walnut oils produced with conventional and organic farming. The method presented good linearity (r2 > 0.9990) for each element at the selected emission line. The limits of detection and limits of quantification ranged between 0.09 μg g−1 to 2.43 μg g−1 and 0.28 μg g−1 to 8.1 μg g−1, respectively. Method accuracy and was assessed by analyzing the certified reference materials BCR 278-R and spiked walnut oil samples. The determined metals were quantified, and the results were analyzed by Student’s t-test to investigate the differences in the elemental profile of the walnut oils according to type of farming (conventional or organic). Full article
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Article
Targeted Characterization of the Chemical Composition of JUUL Systems Aerosol and Comparison with 3R4F Reference Cigarettes and IQOS Heat Sticks
Separations 2021, 8(10), 168; https://doi.org/10.3390/separations8100168 - 03 Oct 2021
Viewed by 348
Abstract
Aerosol constituent yields have been reported from a wide range of electronic nicotine delivery systems. No comprehensive study has been published on the aerosol constituents generated from the JUUL system. Targeted analyses of 53 aerosol constituents from the four JUUL products currently on [...] Read more.
Aerosol constituent yields have been reported from a wide range of electronic nicotine delivery systems. No comprehensive study has been published on the aerosol constituents generated from the JUUL system. Targeted analyses of 53 aerosol constituents from the four JUUL products currently on the US market (Virginia Tobacco and Menthol flavored e-liquids in both 5.0% and 3.0% nicotine concentration by weight) was performed using non-intense and intense puffing regimens. All measurements were conducted by an ISO 17025 accredited contract research organization. JUUL product aerosol constituents were compared to published values for the 3R4F research cigarette and IQOS Regular and Menthol heated tobacco products. Across the four JUUL products and two puffing regimes, only 10/53 analytes were quantifiable, including only two carbonyls (known propylene glycol or glycerol degradants). The remaining analytes were primary ingredients, nicotine degradants and water. Average analyte reductions (excluding primary ingredients and water) for all four JUUL system aerosols tested were greater than 98% lower than 3R4F mainstream smoke, and greater than 88% lower than IQOS aerosol. In summary, chemical characterization and evaluation of JUUL product aerosols demonstrates a significant reduction in toxicants when compared to mainstream cigarette smoke from 3R4F reference cigarettes or aerosols from IQOS-heated tobacco products. Full article
(This article belongs to the Special Issue Method Development and Applications for Reduced-Risk Products)
Article
Influence of Harvest Time, Method of Preparation and Method of Distillation on the Qualitative Properties of Organically Grown and Wild Helichrysum italicum Immortelle Essential Oil
Separations 2021, 8(10), 167; https://doi.org/10.3390/separations8100167 - 03 Oct 2021
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Abstract
The most important process in immortelle is the extraction of the essential oil by distillation. The chemical properties of the plant depend largely on the cultivation type, climatic conditions and agrotechnical measures. In this work, studies were carried out on organically grown and [...] Read more.
The most important process in immortelle is the extraction of the essential oil by distillation. The chemical properties of the plant depend largely on the cultivation type, climatic conditions and agrotechnical measures. In this work, studies were carried out on organically grown and wild immortelle harvested during the summer (July) and autumn (October) seasons of 2020. Immortelle samples were prepared by drying naturally in two ways: in direct sunlight and in shade. To extract the essential oil, immortelle was distilled in two ways: on an industrial and a laboratory scale. The essential oil was analyzed by gas chromatography to determine the composition and quality of the essential oil. The results of this work showed that the qualitative properties of the essential oil were influenced by the cultivation type, harvesting time, preparation method and distillation method. A higher yield (0.21% ± 0.03) of essential oil was obtained from wild immortelle whereas a better utilization rate (0.38% ± 0.09) of essential oil was obtained from the organically grown immortelle. It was also found that a higher yield of essential oil was obtained from the summer harvest (0.19% ± 0.01) and a higher utilization rate from the autumn harvest (0.33% ± 0.13) with the industrial scale distillation and shade drying. In general, better qualitative properties of immortelle essential oil were obtained from wild immortelle, which was confirmed by a chromatographic analysis and better content of γ-curcumene (16.64% ± 0.30) and neryl acetate (8.15% ± 0.19) and other constituents except α-pinene where organically grown had a higher share (24.27% ± 0.97). Full article
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Article
Rolling Circle and Loop Mediated Isothermal Amplification Strategy for Ultrasensitive miRNA Detection
Separations 2021, 8(10), 166; https://doi.org/10.3390/separations8100166 - 03 Oct 2021
Viewed by 248
Abstract
Rolling circle amplification (RCA) and loop mediated isothermal amplification (LAMP) were combined to establish the rolling circle and loop mediated isothermal amplification (RC-LAMP) method for miRNA detection. With the participation of Bst 2.0 DNA Polymerase, the method enabled RCA and LAMP amplification to [...] Read more.
Rolling circle amplification (RCA) and loop mediated isothermal amplification (LAMP) were combined to establish the rolling circle and loop mediated isothermal amplification (RC-LAMP) method for miRNA detection. With the participation of Bst 2.0 DNA Polymerase, the method enabled RCA and LAMP amplification to occur simultaneously without thermal cycling. The limit of detection of RC-LAMP was 500 amol/L, which is comparable to previously reported amplification strategies. Moreover, its upper limit of quantitation was higher and showed a stronger resistance to matrix interference. Therefore, it is possible to detect low concentrations of miRNA in samples by increasing the total RNA added. Owing to its facile detection mode and simple operation, this method has great potential in clinical sample detection. Full article
(This article belongs to the Special Issue Early Career Stars in Bioanalysis/Clinical Analysis)
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Article
Enantioselective Chromatographic Separation and Lipase Catalyzed Asymmetric Resolution of Biologically Important Chiral Amines
Separations 2021, 8(10), 165; https://doi.org/10.3390/separations8100165 - 30 Sep 2021
Viewed by 307
Abstract
Cyanoacetamides are vital synthons in synthetic organic chemistry. However, methods to enantiopure cyanoacetamides have not yet been well explored. In this work, the preparation of cyanoacetamide synthons RS-(1a4a) or methoxyacetamides RS-(1b4b) in enantiopure/enriched [...] Read more.
Cyanoacetamides are vital synthons in synthetic organic chemistry. However, methods to enantiopure cyanoacetamides have not yet been well explored. In this work, the preparation of cyanoacetamide synthons RS-(1a4a) or methoxyacetamides RS-(1b4b) in enantiopure/enriched form was investigated. Compounds S-1, S-2, R-1b, R-1a, andR-2b were prepared in enantiopure form (ee > 99%) while compounds S-4, R-2a, and R-4a were achieved in ee 9%, 80%, and 76%, respectively. Many baselines enantioselective HPLC separations of amines 14, their cyanoacetamides (1a4a), and methoxyacetamides (1b4b) were achieved by utilizing diverse mobile-phase compositions and two cellulose-based CSPs (ODH® and LUX-3® columns). Such enantioselective HPLC separations were used to monitor the lipase-catalyzed kinetic resolution of amines RS-(14). Full article
(This article belongs to the Special Issue Separations in Biomedical Analysis)
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