Elution Solvent Research Articles

Novel Application of Metal-Organic Frameworks as Efficient Sorbents for Solid-Phase Extraction of Chemical Warfare Agents and Related Compounds in Water Samples.

In this work, we test metal-organic frameworks (MOFs) as sorbents in the solid-phase extraction (SPE) technique to determine chemical warfare agents (CWAs) and their related compounds in water samples. During this study, we used 13 target compounds to test the selectivity of MOFs thoroughly. Three MOFs were used: MIL-100(Fe), ZIF-8(Zn), and UiO-66(Zr). The obtained materials were characterized using FT-IR/ATR, SEM, and XRD. CWA's and related compounds were analyzed using gas chromatography coupled with tandem mass spectrometry (GC-MS/MS). The effect of the type of elution solvent and the amount of sorbent (MOFs) in the column on the efficiency of the conducted extraction were verified. The LOD ranged from 0.04 to 7.54 ng mL-1, and the linearity range for the analytes tested extended from 0.11/22.62 (depending on the compound) to 1000 ng mL-1. It was found that MOFs showed the most excellent selectivity to compounds having aromatic rings in their structure or a "spread" spatial structure. The best recoveries were obtained for DPAA, CAP, and malathion. Environmental water samples collected from the Baltic Sea were analyzed using an optimized procedure to verify the developed method's usefulness.

Ionic-liquid/Carbowax 20 M functionalized capsule phase microextraction platform for the extraction of phosphodiesterase-5 inhibitors from human serum and urine prior to their determination by LC–MS

Capsule phase microextraction (CPME) is an efficient bioanalytical technique that streamlines the sample preparation by integrating the filtration and stirring mechanism directly into the device. A novel composite sorbent designed to be selective towards the target analytes consisting of mixed-mode sorbent chemistry synthesized by sol–gel technology is found promising and superior to the conventional C18 sorbents. Herein we describe the encapsulation of an ionic liquid (IL)/Carbowax 20M-functionalized sol–gel sorbent (sol–gel IL/Carbowax 20 M) in the lumen of porous polypropylene tubes for the capsule phase microextraction of three phosphodiesterase-5 inhibitors namely avanafil, sildenafil, and tadalafil in human serum and urine samples. The CPME device was characterized by Scanning Electron Microscopy (SEM) and Fourier-Transform Infrared Spectroscopy (FT-IR). The experimental parameters of CPME procedure (e.g. sample pH and ionic strength, extraction time, stirring rate, elution solvent and volume) were carefully optimized to achieve the highest possible extraction efficiency for the analytes. Method validation was conducted in terms of precision, linearity, accuracy, matrix effect, lower limits of quantification, and limits of detection (LOD). The method linearity was investigated in the range of 50–1000 ng mL−1 for all analytes while the precision was less than 11.8 % in all cases. For all analytes, the LOD values were 17 ng mL−1. The IL/CW 20M-functionalized microextraction capsules could be reused at least 25 times both for urine and serum samples. The green character and the applicability of the proposed method were evaluated using the ComplexGAPI and BAGI indexes. The optimized CPME protocol exhibited reduced consumption of organic solvent and generation of waste, cost-effectiveness, and simplicity. Finally, the proposed method was successfully applied to the analysis of sildenafil in human urine after administration of drug-containing formulation.

Interface Interaction of Waste Rubber–Asphalt System

Asphalt pavement construction is a large-volume project, with the ability to recycle the industrial waste and reduce carbon emissions. Rubber-modified asphalt is a carbon-neutralized asphalt-based material, facilitating the recycling of waste rubber materials and improving the road performance of the asphalt mixture. To evaluate the interface interaction of the rubber–asphalt system and its effect on the viscosity characteristics of rubber-modified asphalt, the contact properties of rubber particles in asphalt were analyzed on a microscopic level. Rubber swelling tests and solvent elution tests were conducted on the rubber–asphalt system under different preparation conditions. The swelling ratio, degradation ratio, and swelling–degradation ratio were proposed to evaluate the interface interaction. The results show that the interface interaction of the rubber–asphalt system can be divided into the following three stages: swelling, effective degradation, and over-degradation. The degree of swelling is mainly affected by the content and size of the rubber particles and it is physically condensed, while the degradation is mainly affected by the preparation temperature and preparation time. The effective interface interaction greatly affects the viscosity with the building of the stable three-dimensional network structure. The stronger the interface interaction, the greater the viscosity of the rubber-modified asphalt, except for the 25% content of rubber particles. The gel film will be generated on the surface of the rubber particles throughout the swelling and effective degradation, increasing the viscosity of the rubber-modified asphalt.

Highly efficient purification of long-chain alkenones using silver dimercaptotriazine flash chromatography

Long-chain alkenones (LCAs) are important tools for paleotemperature reconstructions in lacustrine and marine environments. However, some neutral lipid compounds that co-elute with LCAs often occur in natural sediment samples, which seriously interferes with the identification and quantification of the LCAs. In this study, we report a new flash column chromatography based on silver(I)-dimercaptotriazine (Ag-DMT) functionalized silica material (≡Si-DMT-Ag) for purifying and isolating the individual LCAs from complex lake and marine sediment samples. Compared to silver(I)-mercaptopropyl (Ag-MP) functionalized (≡Si-(CH2)3-S-Ag) and silver nitrate (SiO2 + AgNO3) impregnated silica materials used by previous studies, the Ag-DMT stationary phase displays the best efficiency in removing co-eluting compounds (including wax ester, hopanoid, hopanoic acid, sterane, alkanoic acid, and some unknown compounds) from the LCAs in our study lake and marine sediment samples. The Ag-DMT material also shows its high retention capacity for the LCAs, probably due to a strong interaction of more positively charged silver sites on Ag-DMT with double bonds. Employing the Ag-DMT chromatography, we develop an optimal solvent elution scheme to efficiently isolate the individual LCAs with the same chain length but different numbers of unsaturation for their isotopic analysis in the future. Our study provides a highly effective method for eliminating co-eluting compounds and isolating individual LCAs for paleoclimate studies.

In-tip-fabric phase sorptive extraction (In-tip-FPSE): A proof of concept study for on-site and in-laboratory sample preparation of antidepressants and benzodiazepines

In forensic toxicology, the accurate identification and quantification of drugs are essential for medico-legal investigations. However, the challenge of drug stability complicates this task. On-site extraction (OSE) offers a solution, eliminating the need for sample transportation and storage, reducing degradation risks, and enhancing time, cost, and data quality. In the present work, we propose an innovative approach: In-tip-fabric phase sorptive extraction (In-tip-FPSE), designed for both on-site and in-laboratory sample preparation of antidepressants (ADs) and benzodiazepines (BZDs) from urine and postmortem blood samples. Initially, a sol–gel Carbowax 20 M (CW20M) coated FPSE membrane was prepared using unbleached cotton as the fabric substrate. For the fabrication of the In-tip-FPSE device, two cleaned FPSE membranes (1 cm × 1.5 cm) were positioned inside a 1 mL micropipette tip and fitted into a standard micropipette. The extraction procedure involves repeated aspirating/dispensing cycles (40 times) of the diluted samples within the micropipette tip to facilitate efficient extraction onto the FPSE membrane. Subsequently, elution is achieved by aspirating 1 mL of methanol (MeOH), followed by vertical positioning of the micropipette for 10 min, after which the eluted MeOH is dispensed into a GC–MS vial for analysis. Optimization of the In-tip-FPSE procedure involved exploring parameters such as the type and size of membrane, number of aspirating/dispensing cycles, type and volume of elution solvent, sample pH, and ionic strength. Under optimized conditions, the limit of quantification (LOQ) ranged from 33-41 µg/L and 42–49 µg/L for urine and blood, respectively. The relative standard deviation for intra and inter-day precision was less than 4 % and 10 %, respectively. The method exhibited excellent linearity in the range of 5–5000 µg/L for both matrices with a coefficient of determination (R2) in the range of 0.998 – 0.999. Absolute recovery (AR%) values for this method in real samples ranged from 85%-110 %. Furthermore, the practicality, greenness, and sustainability of the In-tip-FPSE method were assessed, demonstrating its superiority over previously reported in-laboratory methods. Finally, the method was successfully applied for OSE of target analytes from urine samples and in-laboratory analysis of postmortem blood samples.

Preparation and optimization of dummy molecularly imprinted polymer-based solid-phase extraction system for selective enrichment of p-toluene sulfonate esters genotoxic impurities

Sulfonate esters, one class of genotoxic impurities (GTIs), have gained significant attention in recent years due to their potential to cause genetic mutations and cancer. In the current study, we employed the dummy template molecular imprinting technology with a dummy template molecule replacing the target molecule to establish a pretreatment method for samples containing p-toluene sulfonate esters. Through computer simulation and ultraviolet–visible spectroscopy analysis, the optimal functional monomer acrylamide and polymerization solvent chloroform were selected. Subsequently, a dummy template molecularly imprinted polymer (DMIP) was prepared by the precipitation polymerization method, and the polymer was characterized in morphology, particle size, and composition. The results of the adsorption and enrichment study demonstrated that the DMIP has high adsorption capability (Q = 7.88 mg/g) and favorable imprinting effects (IF = 1.37); Further, it could simultaneously adsorb three p-toluene sulfonate esters. The optimal adsorption conditions were obtained by conditional optimization of solid-phase extraction (SPE). A pH 7 solution was selected as the loading condition, the methanol/1 % phosphoric acid solution (20:80, v/v) was selected as the washing solution, and acetonitrile containing 10 % acetic acid in 6 mL was selected as the elution solvent. Finally, we determined methyl p-toluene sulfonate alkyl esters, ethyl p-toluene sulfonate alkyl esters, and isopropyl p-toluene sulfonate alkyl esters in tosufloxacin toluene sulfonate and capecitabine at the 10 ppm level (relative to 1 mg/mL active pharmaceutical ingredient (API) samples) by using DMIP-based SPE coupled with HPLC. This approach facilitated the selective enrichment of p-toluene sulfonate esters GTIs from complex API samples.

Solvent Bar Microextraction Method Based on a Natural Deep Eutectic Solvent and Multivariate Optimization for Determination of Steroid Hormones in Urine and Water

Steroid hormones may pose potential risks to both human health and wildlife, primarily through the consumption of medication or polluted food and water; efforts are being made to monitor their levels in the human body and regulate and minimize their releases to the environment. In this study, a simple and environmentally friendly sample preparation method was developed to simultaneously determine three steroid hormones in urine and water samples. A monoterpene (menthol) and a fatty acid (lauric acid) were combined in various ratios to form a hydrophobic deep eutectic (HDE) solvent as an extraction solvent in solvent bar microextraction (SBME). Using a univariate strategy, a menthol-to-lauric acid HDE ratio of 4:1 and a pH 7 of the sample solution resulted in the highest extraction efficiency (EE%) of the selected steroids. The computational methods have been employed to predict a 4:1 HDE interaction with chosen steroids. Additionally, chemometric approaches suggested that the optimal extraction conditions involved HDEs as extract solvent confined within three SBME devices directly immersed into a 20 mL sample solution with a 30 min extraction time, followed by ultrasonication within 200 μL of elution solvent for a 5 min elution time. Under optimized conditions, the method calibration graph for the spiked selected steroids in the water and urine samples showed good linearity with R2 ≥ 0.994 with limits of detection/quantification lower than 0.40/1.35 μg L−1 and repeatability/reproducibility (RSD%, n = 5) lower than 5.09/7.11. The developed method allows a safe, rapid, and reliable analysis of three steroid hormones in human urine and water samples without using toxic volatile organic solvents.

Separation and Detection of Catechins and Epicatechins in Shanxi Aged Vinegar Using Solid-Phase Extraction and Hydrophobic Deep Eutectic Solvents Combined with HPLC.

This research presents a new, eco-friendly, and swift method combining solid-phase extraction and hydrophobic deep eutectic solvents (DES) with high-performance liquid chromatography (SPE-DES-HPLC) for extracting and quantifying catechin and epicatechin in Shanxi aged vinegar (SAV). The parameters, such as the elution solvent type, the XAD-2 macroporous resin dosage, the DES ratio, the DES volume, the adsorption time, and the desorption time, were optimized via a one-way experiment. A central composite design using the Box-Behnken methodology was employed to investigate the effects of various factors, including 17 experimental runs and the construction of three-dimensional response surface plots to identify the optimal conditions. The results show that the optimal conditions were an HDES (tetraethylammonium chloride and octanoic acid) ratio of 1:3, an XAD-2 macroporous resin dosage of 188 mg, and an adsorption time of 11 min. Under these optimal conditions, the coefficients of determination of the method were greater than or equal to 0.9917, the precision was less than 5%, and the recoveries ranged from 98.8% to 118.8%. The environmentally friendly nature of the analytical process and sample preparation was assessed via the Analytical Eco-Scale and AGREE, demonstrating that this method is a practical and eco-friendly alternative to conventional determination techniques. In summary, this innovative approach offers a solid foundation for the assessment of flavanol compounds present in SAV samples.

Phytochemical Screening and Antidiabetic Efficacy of Balanites aegyptiaca Seed Extract and Their Silver Nanoparticles on Muscle and Pancreatic Cell Lines.

Balanites aegyptiaca (L.) Delile, a member of the Zygophyllaceae family, is commonly known as the desert date. This tree is famous for yielding edible fruits and is esteemed for its nutritional richness and diverse health advantages. The primary aim of this research was to assess the potential antidiabetic and cytotoxic effects of seed extracts from B. aegyptiaca and its AgNPs for the first time on C2C12 and MIN6 cells, focusing on glucose uptake and insulin secretion, respectively. Additionally, the seed extracts underwent column chromatography through different solvent systems, resulting in the isolation of five distinct fractions with a mixture of methanol and water as an eluting solvent in different ratios. Comprehensive characterization of the aqueous seed extract was carried out using GC-MS and UPLC-MS. The study determined that the aqueous seed extract exhibited no toxicity at any tested concentration (6.25-100 μg/mL) on both cell types. The calculated IC50 values were 206.00 and 140.44 μg/mL for C2C12 and MIN6 cells, respectively, for seeds of AgNPs. Additionally, the aqueous seed extract and their AgNPs significantly increased glucose uptake by 150.45% and 156.00% of the control in C2C12 cells at a concentration of 100 μg/mL. Insulin secretion was also notably enhanced by 3.47- and 3.92-fold of the control after administering seed extracts and AgNPs, respectively, at 100 μg/mL. GC-MS and UPLC-MS analyses identified various compounds across different categories. Notably, the F2 fraction (methanol and water in ratio of 80:20 as eluting solvent) exhibited the highest glucose uptake activity (156.81% of control), while the F3 fraction (methanol and water in ratio of 70:30 as eluting solvent) fraction demonstrated the highest insulin secretion activity (3.70 folds of the control) among all fractions at 100 μg/mL. GC-MS analysis was employed to characterize both fractions, aiming to identify the compounds contributing to their antidiabetic potential. The study's findings concluded that both seed extracts and their AgNPs possess significant antidiabetic properties, with elevated activity observed in the case of AgNPs in both assays. Various compounds, including diosgenin, oleic acid, linoleic acid and palmitic acid esters were detected in the seed extracts, known for their reported antidiabetic and hypoglycemic effects.

Contamination Levels and Accumulation Profiles of Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Sediments from South Central Coast of Vietnam

Contamination Levels and Accumulation Profiles of Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Sediments from South Central Coast of Vietnam

COF-SiO2@Fe3O4 Composite for Magnetic Solid-Phase Extraction of Pyrethroid Pesticides in Vegetables.

Pyrethroid pesticides (PYRs) have found widespread application in agriculture for the protection of fruit and vegetable crops. Nonetheless, excessive usage or improper application may allow the residues to exceed the safe limits and pose a threat to consumer safety. Thus, there is an urgent need to develop efficient technologies for the elimination or trace detection of PYRs from vegetables. Here, a simple and efficient magnetic solid-phase extraction (MSPE) strategy was developed for the simultaneous purification and enrichment of five PYRs in vegetables, employing the magnetic covalent organic framework nanomaterial COF-SiO2@Fe3O4 as an adsorbent. COF-SiO2@Fe3O4 was prepared by a straightforward solvothermal method, using Fe3O4 as a magnetic core and benzidine and 3,3,5,5-tetraaldehyde biphenyl as the two building units. COF-SiO2@Fe3O4 could effectively capture the targeted PYRs by virtue of its abundant π-electron system and hydroxyl groups. The impact of various experimental parameters on the extraction efficiency was investigated to optimize the MSPE conditions, including the adsorbent amount, extraction time, elution solvent type and elution time. Subsequently, method validation was conducted under the optimal conditions in conjunction with gas chromatography-mass spectrometry (GC-MS). Within the range of 5.00-100 μg·kg-1 (1.00-100 μg·kg-1 for bifenthrin and 2.5-100 μg·kg-1 for fenpropathrin), the five PYRs exhibited a strong linear relationship, with determination coefficients ranging from 0.9990 to 0.9997. The limits of detection (LODs) were 0.3-1.5 μg·kg-1, and the limits of quantification (LOQs) were 0.9-4.5 μg·kg-1. The recoveries were 80.2-116.7% with relative standard deviations (RSDs) below 7.0%. Finally, COF-SiO2@Fe3O4, NH2-SiO2@Fe3O4 and Fe3O4 were compared as MSPE adsorbents for PYRs. The results indicated that COF-SiO2@Fe3O4 was an efficient and rapid selective adsorbent for PYRs. This method holds promise for the determination of PYRs in real samples.

Synthesis of nano magnetic chitosan modified with acrylamide schiff’s base for simultaneous removal of Cu(II) and Co(II) from waste water samples

ABSTRACT A magnetic nano sorbent based on the functionalization of magnetic chitosan with acrylamide was synthesized for Cu(II) and Co(II) removal from wastewater samples. To characterize the magnetic nano sorbent, they have been applied from Fourier transform infrared spectroscopic analysis (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The effective parameters of Cu(II) and Co(II) adsorption on magnetic nano sorbent such as pH of the solution, adsorbent dose, contact time and sample volume, were optimized. Also, the effective parameters on Cu(II) and Co(II) desorption conditions (type and volume of elution solvent) were optimized. The isotherms and kinetics models for the adsorption of Cu(II) and Co(II) on the magnetic nano sorbent were studied. The data were well-fitted with the Langmuir isotherm and pseudo-second-order model. The maximum adsorption capacities for Cu(II) and Co(II) were 165.4 and 159.9 mg g-1, respectively. Also, the thermodynamic parameters were studied. Application of magnetic nano sorbent for 4 times of use was acceptable. For the real samples, the percentage of recovery was higher than 97% and RSD (%) was between 1.4% and 2.7%. Finally, the magnetic nano sorbent exhibited high performance in removing the Cu(II) and Co(II) from wastewater samples.

Integrated Multiplatform Analysis and Separation of Thirteen Flavonoids and Anthraquinones in Seven Medicinal Cassia Species.

Cassia (Family: Fabaceae) species are a large group of flowering plants rich in bioactive anthraquinone and flavonoids used in botanical supplements and nutraceuticals. A simple and reliable high-performance liquid chromatography-photodiode array (HPLC-PDA) method was developed and validated for separating and quantifying 13 anthraquinone and flavonoids. These compounds were further confirmed using an LC-based electrospray ionization mass spectrometry (ESI-MS/MS) method in the leaves and flowers of selected Cassia species. A simple and rapid HPTLC method was developed for chemical fingerprint analysis of all Cassia species. All 13 compounds were chromatographically separated on a Zorbax TC18 (4.6 × 250, 5 μm particle size) analytical column, and 0.1% formic acid and acetonitrile as elution solvents at a flow rate of 0.8 mL/min with detection at 259 nm. For HPTLC fingerprinting, the mobile phase compositions of toluene, ethyl acetate, and formic acid (5.5:4.2:0.6, v/v/v) were optimized to separate and identify all compounds using silica gel 60F254 aluminum plates. The validation data for the developed HPLC-PDA method for 13 compounds showed good linearity (r2 >0.99) with a sensitive LOD (0.082-1.969 μg/mL), LOQ (0.250-5.967 μg/mL), and excellent recoveries (85.22-100.32%). The quantification results were found to be precise and accurate (<5.0% and relative error), -0.77-0.44 with ESI-MS/MS confirmation in the Cassia samples. The novel HPTLC method was excellent separation for 13 compounds, with Rf values ranging between 0.12 and 0.61. The developed HPLC-PDA method was simple and precise and could separate and quantify anthraquinones and flavonoids along with confirmation, using a novel LC-based ESI-MS/MS. The HPTLC method was found to be simple and precise, with excellent separation capabilities for these compounds. This novel multiplatform approach successfully identified and quantified 13 compounds simultaneously using an integration of data strategy in seven medicinally important Cassia species' leaves and flowers.

Evaluation of the cytotoxic and antimicrobial potential of epiphytic biomass obtained from Laminaria hyperborea biorefinery side-streams

Harvested Laminaria hyperborea contributes to approximately 3.3 million tonnes of epiphytes discarded as waste despite containing organisms such as red algae and bryozoa, known to produce a range of high-value and bioactive compounds. Our research aim is to valorize epiphyte biomass by exploring the cytotoxic and antimicrobial potential in various extracts and optimized fractionation by flash chromatography. All extracts and fractions were tested for cytotoxicity towards cell lines derived from Acute Myeloid Leukemia (AML), prostate cancer (PC-3), and breast cancer (MCF-7), as well as non-tumorigenic cell lines from the kidney and heart using metabolic activity as a read-out. Antimicrobial activity was assessed using microplate based Alamar Blue assay and minimum inhibitory concentration (MIC) to determine the MIC against various human pathogens. Six extracts demonstrated significant cytotoxicity across all five cell lines (EC50 values below 46 µg/mL), while hexane extract selectively targeted AML cells with EC50 of 1.1 µg/mL. The hexane and ethyl acetate extracts displayed antimycobacterial and antifungal activity (MIC 100 µg/mL). A multistep flash fractionation of the methanolic extract revealed several cytotoxic and antimicrobial activities. The flash fractions displayed a selective activity pattern depending on the elution solvent. Nine fractions were cytotoxic towards all cell lines (EC50 below 72 µg/mL), and four were highly cytotoxic (EC50 below 5.4 µg/mL). Two non-polar fractions were selective for the AML cell line. These results highlight the potential for discovering anticancer and antimicrobial compounds in epiphytes from Laminaria, necessitating further research on their active compounds. Overall, this work underscores the environmental and scientific value of converting marine by-products into a valuable resource, aligning with sustainability and ethical goals.

Analysis and Assessment of Contamination Degree and Emission Sources of Polycyclic Aromatic Hydrocarbons (PAHs and Me-PAHs) in Surface Sediments from Central Coast of Vietnam

Polycyclic aromatic hydrocarbons (PAHs) and their derivatives are a diverse group of organic pollutants, which are relatively persistent and toxic. Simultaneous determination of unsubstituted PAHs and methylated PAHs (Me-PAHs) is necessary to provide comprehensive insights into contamination levels and sources of these pollutants. In this study, we collected surface sediment samples in Vietnamese central coast to analyze 7 PAHs and 12 Me-PAHs. The sediment samples were extracted by using a focused ultrasonic processor with acetone/hexane (1:1) mixture and toluene. The extract was purified by column chromatography technique with activated silica gel and dichloromethane/hexane (1:3) as elution solvent. PAHs and Me-PAHs were determined by a gas chromatography/mass spectrometry (GC/MS) system operated in electron impact ionization (EI) and selected ion monitoring mode (SIM). Concentrations of total 7 PAHs and 12 Me-PAHs ranged from 30 to 246 (average 92) nanograms per gram sediment (ng/g). These levels were comparable to or lower than those measured in Vietnamese river sediments and marine sediments from some other countries in the world. The accumulation profiles of PAHs and Me-PAHs indicated that their emissions are likely associated with mixed pyrogenic and petrogenic sources. Our results have provided preliminary information about the pollution degree and accumulation characteristics of these substances in Vietnamese marine environments. Additional comprehensive studies should be performed to characterize contamination characterisrics, emission sources, and ecological risks of PAHs and their derivatives in this country.

The potential of polyaniline-coated stationary phase in hydrophilic interaction liquid chromatography-based solid-phase extraction for glycopeptide enrichment

Glycopeptide enrichment is a crucial step in glycoproteomic analysis, often achieved through solid-phase extraction (SPE) on polar stationary phases in hydrophilic interaction liquid chromatography (HILIC). This study explores the potential of polyaniline (PANI)-coated silica gel for enriching human immunoglobulin G (IgG). Experimental conditions were varied to assess their impact on glycopeptide enrichment efficiency, comparing PANI-cotton wool SPE with conventional cotton wool as SPE sorbents. Two formic acid concentrations (0.1% and 1%) in elution solvent were tested, revealing that higher concentrations led to earlier elution of studied glycopeptides, especially for sialylated glycopeptides. Substituting formic acid with acetic acid increased the interaction of neutral glycopeptides with the PANI-modified sorbent, while sialylated glycopeptides showed no significant change in enrichment efficiency. Acetonitrile concentration in the elution solvent (5%, 10%, and 20%) affected the enrichment efficiency with most glycopeptides eluting at the lowest acetonitrile concentration. The acetonitrile concentration in conditioning and washing solutions (65%, 75%, and 85%) played a crucial role; at 65% acetonitrile, glycopeptides were least retained on the stationary phase, and neutral glycopeptides were even detected in the flow-through fraction. This study shows the potential of in-house-prepared PANI-modified sorbents for SPE-HILIC glycopeptide enrichment, highlighting the crucial role of tuning experimental conditions in sample preparation to enhance enrichment efficiency and selectivity.

Quantification of serine residue stereoinversion in a short peptide by reversed-phase high-performance liquid chromatography: analysis of mechanisms promoting serine stereoinversion.

Stereoinversion of Ser residues within proteins, which has been identified in long-lived proteins, influences protein function. To quantify the stereoinversion of Ser residues, we investigated the potential adaptation of our direct peptide analytical method originally established for analyzing the isomerization of asparaginyl/aspartyl residues. Peptide pairs containing L-Ser or D-Ser residues with lengths of four or five residues were synthesized. Separation conditions for these peptide pairs were systematically examined by precisely adjusting the pH of the elution solvent using reverse-phase high-performance liquid chromatography (HPLC). Optimal separation conditions were successfully developed for all peptide pairs, enabling the direct quantification of Ser residue stereoinversion through a single HPLC run. Subsequently, the degree of Ser stereoinversion within the model peptide, Gly-Ser-Gly-Tyr, was determined using the method established in this study. Surprisingly, the stereoinversion of Ser residues occurred only when the absolute configurations of Ser and Tyr residues of the peptide differed from each other, whereas no stereoinversion was observed when their absolute configurations were identical. The experiments using peptides similar to the model peptide reveal that both the N-terminal amino group and the hydroxyl group of the C-terminal Tyr residue are involved in the stereoinversion of the Ser residue. By applying a simple method to quantify the stereoinversion of Ser residues, valuable insights into the mechanisms governing these stereoinversions were obtained.

Determination of triazole fungicides in soybeans with cobalt-enhanced lanthanide metal chloride anion magnetic deep eutectic solvents in-situ dispersion extraction

In this work, we synthesized a series of magnetic deep eutectic solvents (MDESs) with lanthanide metal chlorides as paramagnetic metal centers and developed a reversed-phase dispersive liquid–liquid microextraction method (DLLME) based on the in-situ dispersion of MDESs for the extraction and preconcentration of triazole fungicides (TFs) from bean samples. Different MDESs were synthesized by combining quaternary ammonium salts, short-chain carboxylic acids, and lanthanide metal chlorides. The dissolution of short-chain carboxylic acids in n-hexane led to the in-situ dispersion of MDESs to replace the toxic dispersant of traditional DLLME species and shorten extraction time. Cobalt powder was added to encapsulate MDESs to enhance the magnetic properties after the extraction and achieve the purpose of easy phase separation. Notably, the highest extraction efficiency of TFs was observed in the MDES formed by tetrabutylammonium bromide, propionic acid, and gadolinium chloride in a ratio of 1:10:0.06. We optimized various parameters that affected the extraction efficiency of the method, including volume of MDES, extraction time, amount of cobalt powder, and volume of elution solvent. Under the optimal conditions, the detection limits (LODs) and quantification limits (LOQs) of the technique varied between 0.097–0.13 ng·g−1 and 0.32–0.43 ng·g−1, respectively. To assess the accuracy, the method was tested with samples spiking at three concentration levels, and the obtained results revealed that the recovery rates varied from 88.97–113.7%. To summarize, this study represents the initial application of in-situ dispersed lanthanide metal chloride anion-MDESs for analyzing bean samples and the proposed DLLME technique is rapid, straightforward, and efficient.

Simultaneous determination of twelve neonicotinoids and six metabolites in human urine with isotope-dilution UPLC-Q-Orbitrap HRMS

The extensive global use of neonicotinoid insecticides (NNIs) has led to widespread human exposure, necessitating the development of effective methods for large-scale biomonitoring. However, current methods are inadequate in simultaneously and accurately detecting various NNIs or their metabolites (m-NNIs). In this study, we aimed to establish a robust method using solid-phase extraction (SPE)-ultra high performance liquid chromatography tandem Q-Orbitrap high resolution mass spectrometry (UPLC-Q-Orbitrap HRMS) for the simultaneous determination of 12 NNIs and 6 m-NNIs in human urine. Samples were prepared using Oasis HLB 96 well plate with Isopropanol: methanol (7:3, v/v) as the elution solvent. The target compounds were separated using the Accucore RP-MS column and subsequently analyzed under parallel reaction monitoring mode. NTN32692 (m/z = 255.06433) was confirmed to be the specific metabolite of cycloxaprid for the further detection. Satisfactory recoveries (81.6–122.4 %) of the NNIs and m-NNIs were observed, with intra- (n = 3) and inter-day (n = 9) relative standard deviation (RSD) ranging from 0.8 % to 13.7 % and from 1.1 % to 18.6 %, respectively. Good linearity (R2 > 0.99) was achieved for all analytes. The limits of detection (LODs) for all target analytes ranged from 0.01 ng/mL to 0.65 ng/mL. This method was applied to urine samples collected from 10 children recruited from an agricultural area in China. Our study provides an effective method to identify and assess human exposure to NNIs and their metabolites.

The Application of Pipette-Tip and Magnetic Dummy-Template Molecularly Imprinted Solid-Phase Extraction Coupled with High-Performance Liquid Chromatography with Diode Array and Spectrofluorimetric Detection for the Determination of Coumarins in Cosmetic Samples

In this study, adsorbents based on molecularly imprinted polymers (MIPs) in two solid-phase extraction application forms, pipette tip and magnetic extraction, were used for the selective extraction of coumarins. The pipette-tip solid-phase extraction reduced solvent volumes; the magnetic MIP extraction was simple and effective for phase separation. Parameters affecting extraction, such as the amount of adsorbent, type of washing solvent, volume of the elution solvent, and extraction times for magnetic extraction, were optimized. The MIP-based adsorbents displayed high selectivity and extraction efficiency, resulting in recoveries ranging from 70.3 to 102.0% (RSD % less than 5.5%) for five coumarins under study, 6,7-dihydroxycoumarin-6-β-D-glucoside, coumarin, 7-methoxycoumarin, 6-methylcoumarin, and dicoumarol. The extracts were analyzed by high-performance liquid chromatography with diode array (DAD) and fluorescence (FLD) detectors, reaching limits of quantification of 0.5 and 0.9 µg·mL−1 for coumarin and dicoumarol detected by DAD and 0.001–0.012 µg·mL−1 for the other prohibited simple coumarins when used as a fragrance (detected by FLD). The proposed method was validated and its applicability was shown for the analysis of cosmetic samples like shower gel and perfume.