Dispersive liquid–liquid microextraction with in situ derivatization coupled with gas chromatography and mass spectrometry for the determination of 4‐methylimidazole in red ginseng products containing caramel colors

A rapid analytical method was developed for the determination of 4‐methylimidazole from red ginseng products containing caramel colors by using dispersive liquid–liquid microextraction with in situ derivatization followed by gas chromatography with mass spectrometry. Chloroform and acetonitrile were selected as the extraction and dispersive solvents, and based on the extraction efficiency, their optimum volumes were 200 and 100 μL, respectively. The optimum volumes of the derivatizing agent (isobutyl chloroformate) and catalyst (pyridine), pH, and concentration of NaCl in the sample solution were determined to be 25 and 100 μL, pH 7.6, and 0% w/v, respectively. Validation of the optimized method showed good linearity (R² > 0.999), accuracy (≥89.86%), intra‐ (≤6.70%) and interday (≤4.17%) repeatability, limit of detection (0.96 μg/L), and limit of quantification (5.79 μg/L). The validated method was applied to quantify 4‐methylimidazole in red ginseng juices and concentrates, 4‐methylimidazole was only found in red ginseng juices containing caramel colorant (42.91–2863.4 μg/L) and detected in red ginseng concentrates containing >1% caramel colorant.     

Determination of 19 sulfonamides residues in pork samples by combining QuEChERS with dispersive liquid–liquid microextraction followed by UHPLC–MS/MS

A new simple and rapid pretreatment method for simultaneous determination of 19 sulfonamides in pork samples was developed through combining the QuEChERS method with dispersive liquid–liquid microextraction followed by ultra‐high performance liquid chromatography with tandem mass spectrometry. The sample preparation involves extraction/partitioning with QuEChERS method followed by dispersive liquid–liquid microextraction using tetrachloroethane as extractive solvent and the acetonitrile extract as dispersive solvent that obtained by QuEChERS. The enriched tetrachloroethane organic phase by dispersive liquid–liquid microextraction was evaporated, reconstituted with 100 μL acetonitrile/water (1:9 v/v) and injected into an ultra‐high performance liquid chromatography with a mobile phase composed of acetonitrile and 0.1% v/v formic acid under gradient elution and separated using a BHE C₁₈ column. Various parameters affecting the extraction efficiency were investigated. Matrix‐matched calibration curves were established. Good linear relationships were obtained for all analytes in a range of 2.0–100 μg/kg and the limits of detection were 0.04–0.49 μg/kg. Average recoveries at three spiking levels were in the range of 78.3–106.1% with relative standard deviations less than 12.7% (n = 6). The developed method was successfully applied to determine sulfonamide residues in pork samples.     

Quantitative determination of seven chemical constituents and chemo‐type differentiation of chamomiles using high‐performance thin‐layer chromatography

A simple and rapid high‐performance thin‐layer chromatographic method was developed for the separation and determination of six flavonoids (rutin, luteolin‐7‐O‐β‐glucoside, chamaemeloside, apigenin‐7‐O‐β‐glucoside, luteolin, apigenin) and one coumarin, umbelliferone from chamomile plant samples and dietary supplements. The separation was achieved on amino silica stationary phase using dichloromethane/acetonitrile/ethyl formate/glacial acetic acid/formic acid (11:2.5:3:1.25:1.25 v/v/v/v/v) as the mobile phase. The quantitation of each compound was carried out using densitometric reflection/absorption mode at their respective absorbance maxima after postchromatographic derivatization using natural products reagent (1% w/v methanolic solution of diphenylboric acid‐β‐ethylamino ester). The method was validated for specificity, limits of detection and quantification, precision (intra‐ and interday) and accuracy. The limits of detection and quantification were found to be in the range from 6–18 and 16–55 ng/band for six flavonoids and one coumarin, respectively. The intra‐ and interday precision was found to be <5% RSD and recovery of all the compounds was >90%. The data acquired from high‐performance thin‐layer chromatography was processed by principal component analysis using XLSTAT statistical software. Application of principal component analysis and agglomerative hierarchial clustering was successfully able to differentiate two chamomiles (German and Roman) and Chrysanthemum.     

Dispersive magnetic solid‐phase extraction of phthalate esters from water samples and human plasma based on a nanosorbent composed of MIL‐101(Cr) metal–organic framework and magnetite nanoparticles before their determination by GC–MS

In this study, a magnetic metal–organic framework was synthesized simply and utilized in the dispersive magnetic solid‐phase extraction of five phthalate esters followed by their determination by gas chromatography with mass spectrometry. First, MIL‐101(Cr) was prepared hydrothermally in water medium without using highly corrosive hydrofluoric acid, utilizing an autoclave oven heat supply. Afterward, Fe₃O₄ nanoparticles were decorated into the matrix of MIL‐101(Cr) to fabricate magnetic MIL‐101 nanocomposite. The nanocomposite was characterized by various techniques. The parameters affecting dispersive magnetic solid‐phase extraction efficiency were optimized and obtained as: a sorbent amount of 15 mg; a sorption time of 20 min; an elution time of 5 min; NaCl concentration, 10% w/v; type and volume of the eluent 1 mL n‐hexane/acetone (1:1 v/v). Under the optimum conditions detection limits and linear dynamic ranges were achieved in the range of 0.08–0.15 and 0.5–200 μg/L, respectively. The intra‐ and interday RSD% values were obtained in the range of 2.5–9.5 and 4.6–10.4, respectively. Ultimately, the applicability of the method was successfully confirmed by the extraction and determination of the model analytes in water samples, and human plasma in the range of microgram per liter and satisfactory results were obtained.     

A three‐phase solvent extraction system combined with deep eutectic solvent‐based dispersive liquid–liquid microextraction for extraction of some organochlorine pesticides in cocoa samples prior to gas chromatography with electron capture detection

A sample pretreatment method based on the combination of a three‐phase solvent extraction system and deep eutectic solvent‐based dispersive liquid–liquid microextraction has been introduced for the extraction of four organochlorine pesticides in cocoa samples before their determination by gas chromatography‐electron capture detection. A mixture of sodium chloride, acetonitrile, and potassium hydroxide solution is added to cocoa bean or powder. After vortexing and centrifugation of the mixture, the collected upper phase (acetonitrile) is removed and mixed with a few microliters of N,N‐diethanol ammonium chloride: pivalic acid deep eutectic solvent. Then it is rapidly injected into deionized water and a cloudy solution is obtained. Under optimum conditions, the limits of detection and quantification were found to be 0.011‐0.031 and 0.036‐0.104 ng/g, respectively. The obtained extraction recoveries varied between 74 and 92%. Also, intra‐ (n = 6) and interday (n = 4) precisions were less than or equal to 7.1% for the studied pesticides at a concentration of 0.3 ng/g of each analyte. The suggested method was applied to determine the studied organochlorine pesticide residues in various cocoa powders and beans gathered from groceries in Tabriz city (Iran) and aldrin and dichlobenil were found in some of them.     

Simultaneous analysis of tropane alkaloids in teas and herbal teas by liquid chromatography coupled to high‐resolution mass spectrometry (Orbitrap)

A new method has been developed for the simultaneous determination of 13 tropane alkaloids in tea and herbal teas using high‐performance liquid chromatography coupled to an Exactive‐Orbitrap analyzer. A mixture of methanol, water, and formic acid was used for the extraction of the target compounds followed by a solid‐phase extraction step. The validated method provided recoveries from 75 to 128% with intra‐ and interday precision lower than or equal to 24% (except for apoatropine). Limits of quantification ranged from 5 to 20 μg/kg. Eleven tea and herbal tea samples and two contaminated samples with Datura stramonium seeds were analyzed. Tropane alkaloids were detected in six samples with concentrations from 5 (apoatropine) to 4340 μg/kg (sum of physoperuvine, pseudotropine, and tropine), whereas concentrations from 5 (apoatropine) to 1725 μg/kg (sum of physoperuvine, pseudotropine, and tropine) were found in the contaminated samples.     

Liquid chromatography mass spectrometry for the determination of salvianolic acid B,a natural compound from the herb Danshen in rat plasma and application to pharmacokinetic study

A sensitive and specific liquid chromatographic–electrospray ionization mass spectrometric method was developed for quantification of salvianolic acid B in rat plasma with resveratrol as the internal standard. The analytes were separated on a reversed‐phase column with acetonitrile (40%) and water (60%) containing 0.75% formic acid as mobile phase at a flow rate of 1 mL/min. Liquid–liquid extraction was adopted for the sample preparation, and the analytes were determined using electrospray negative ionization mass spectrometry in the selective monitoring mode. The method was validated over the concentration range 0.1–40 µg/mL using 0.1 mL of plasma with coefficients of correlation >0.999. The intra‐ and inter‐day precisions of analysis were <10%, and accuracy ranged from 94 to 101%. This method was successfully applied to a pharmacokinetics of salvianolic acid B in rats. Copyright © 2009 John Wiley & Sons, Ltd.     

A high‐throughput screening method for determination of multi‐antibiotics in animal feed

A high‐throughput method based on ultrasonic‐assisted extraction, 96‐well plate thin‐film microextraction was established to determinate 18 antibiotics in animal feed. In this method, the extraction was implemented by ultrasonic‐assisted extraction for 30 min with disodium ethylenediaminetetraacetic acid‐McIlvaine buffer (pH 5) containing 6% sodium chloride w/v, purified by thin‐film microextraction and combined with 96‐well plate system to improve the efficiency. Optimization of thin‐film microextraction conditions was performed by methods of single factor and response surface, and finalized as: condition time: 20 min; adsorption time: 55 min; washing time: 5 s with water; desorption time: 30 min with acetonitrile/water (8:2, v/v) containing 0.1% formic acid v/v. Evaluation of different extractive phases showed that polystyrene‐divinylbenzene‐polyacrylonitrile was the optimum coating. The analysis was performed by ultra‐high performance liquid chromatography with tandem mass spectrometry. Recovery, inter‐ and intraday precision, linearity, limit of detection, and quantitation were evaluated. The average recoveries of 18 antibiotics were 66.6–93.5% at three spiked levels, intraday precision was 1–8.4%, and interday precision was 3.0–16.4%. The linearity was good for r² > 0.99. Limits of detection and quantification were found in the range of 1–14 and 4–48 µg/kg, respectively.     

Simultaneous pharmacokinetics and stability studies of physalins in rat plasma and intestinal bacteria culture media using liquid chromatography with mass spectrometry

Physalins are the major steroidal constituent of Physalis plants and display a range of biological activities. For this study, a rapid and sensitive high‐performance liquid chromatography with triple quadrupole mass spectrometry method was developed for the simultaneous quantification of six physalins. Specifically, it was for the quantification of physalin A, physalin B, physalin D, physalin G, 4,7‐didehydroneophysalin B, and isophysalin B in rat plasma and rat intestinal bacteria. After a solid‐phase extraction, analytes and internal standards (prednisolone) were separated on a Shield reverse‐phase C18 column (measuring 3 mm × 150 mm with an internal diameter of 3.5 μm) and determined using multiple reactions in a monitoring mode with a positive‐ion electrospray ionization source. The mobile phase was a mixture of 0.1% formic acid in water (A) and acetonitrile (B) and was used at a flow rate of 0.6 mL/min. The intra‐ and interday precisions were within 15% with accuracies ranging from 86.2 to 114%. The method was validated and successfully applied to pharmacokinetics and stability studies of six physalins in rat plasma and rat intestinal bacteria, respectively. The results showed that physalin B and isophysalin B could not be absorbed by rats, and rat intestinal bacteria could quickly transform physalins.     

Ultra high performance liquid chromatography with tandem mass spectrometry method for determining dinotefuran and its main metabolites in samples of plants,animal‐derived foods,soil, and water

An ultra high‐performance liquid chromatography with tandem triple quadrupole mass spectrometry residue method was developed and validated for the quantification and identification of dinotefuran and its main metabolites 1‐methyl‐3‐(tetrahydro‐3‐furylmethyl) urea and 1‐methyl‐3‐(tetrahydro‐3‐furylmethyl) guanidine in fruit (watermelon), vegetable (cucumber), cereal (rice), animal‐derived foods (milk, egg, and pork), soil, and water. The samples were extracted with acetonitrile containing 15% v/v acetic acid and purified with dispersive solid‐phase extraction with octadecylsilane, primary secondary amine, graphitized carbon black, or zirconia‐coated silica prior to analysis. The method had an excellent linearity (R² ≥ 0.9942, 1–500 μg/L) and satisfactory recoveries (73–102%) at five spiked levels (0.001, 0.01, 0.05, 0.5, and 2 mg/kg) with intra‐ or interday precision in the range of 0.8–9.5% and 3.0–12.8% for the three compounds in the eight matrices. The limits of quantification were 10 μg/kg for 1‐methyl‐3‐(tetrahydro‐3‐furylmethyl) guanidine and 1 μg/kg for 1‐methyl‐3‐(tetrahydro‐3‐furylmethyl) urea and dinotefuran. The applicability of the developed method was demonstrated by determining the occurrence of dinotefuran, 1‐methyl‐3‐(tetrahydro‐3‐furylmethyl) guanidine, and 1‐methyl‐3‐(tetrahydro‐3‐furylmethyl) urea in various samples from plants, animal‐derived foods, and the environment. From 80 samples, 70 contained dinotefuran (0.8–11.7 μg/kg), among which six also contained 1‐methyl‐3‐(tetrahydro‐3‐furylmethyl) urea (water and rice, 0.5–0.9 μg/kg).     

Solid‐phase extraction of phenoxyacetic acid herbicides in complex samples with a zirconium(IV)‐based metal–organic framework

A zirconium(IV)‐based metal–organic framework material (MOF‐808) has been synthesized in a simple way and used for the extraction of phenoxyacetic acids in complex samples. The material has good thermal and chemical stability, large specific surface area (905.36 m²/g), and high pore size (22.18 Å). Besides, it contains a large amount of Zr‐O groups, easy‐to‐form Zr‐O‐H bond with carboxyl groups of phenoxyacetic acids, and possesses biphenyl skeleton structure, easy to interact with compounds through π‐π and hydrophobic interactions. These characteristics make the material very suitable for the extraction of certain compounds with a high extraction efficiency and excellent selectivity. The extraction conditions were optimized, and then an analytical method was successfully established and applied for analysis of actual samples. The solid‐phase extraction method based on prepared material had a wide linear range of 0.2–250 μg/L and a low detection limit of 0.1–0.5 μg/L for four phenoxyacetic acid compounds including 2,4‐dichlorophenoxyacetic acid, 2‐(2,4‐dichlorophenoxy) propionic acid, 4‐chlorophenoxyacetic acid, and dicamba. The relative standard deviations of intra‐ and interday precision were 1.8–3.8 and 4.3–6.9%, and the recoveries after spiking were between 77.1 and 109.3%. The results showed that the material is a desired substituent for the extraction of compounds with benzene ring structure containing carboxyl groups.     

Determination of Sudan dyes in chili pepper powder by online solid‐phase extraction with a butyl methacrylate monolithic column coupled to liquid chromatography with tandem mass spectrometry

A poly(butyl methacrylate‐co‐ethylene dimethacrylate) monolithic column was fabricated and used as a novel sorbent for online solid‐phase extraction coupled to liquid chromatography with tandem mass spectrometry for the simultaneous determination of Sudan I–IV in chili pepper powder. The prepared columns were characterized by scanning electron microscopy, nitrogen adsorption‐desorption, and pressure drop measurements. Online solid‐phase extraction was performed on the synthesized monolithic column using 10 mM ammonium acetate solution as the loading solution with the aid of an online cleanup chromatography system. The desorption of Sudan I–IV was achieved with acetonitrile as the eluting solution at the flow rate of 0.5 mL/min. The extracted analytes were subsequently eluted into a C₁₈ analytical column for chromatographic separation using a mixture of 10% acetonitrile/90% formic acid (0.5%) solution as the mobile phase. Under the optimized conditions, the developed method had linear range of 1.0–50 μg/kg, a detection limit of 0.3 μg/kg, and a quantification limit of 1.0 μg/kg for each analyte. The intraday and interday recoveries of Sudan I–IV in chili pepper powder samples ranged from 94.8 to 100.9% and 94.9 to 99.4%, respectively. The intraday and interday precision were between 3.37–7.01% and 5.01–7.68%, respectively.     

A rapid MCM‐41 dispersive micro‐solid phase extraction coupled with LC/MS/MS for quantification of ketoconazole and voriconazole in biological fluids

A rapid dispersive micro‐solid phase extraction (D‐μ‐SPE) combined with LC/MS/MS method was developed and validated for the determination of ketoconazole and voriconazole in human urine and plasma samples. Synthesized mesoporous silica MCM‐41 was used as sorbent in d ‐μ‐SPE of the azole compounds from biological fluids. Important D‐μ‐SPE parameters, namely type desorption solvent, extraction time, sample pH, salt addition, desorption time, amount of sorbent and sample volume were optimized. Liquid chromatographic separations were carried out on a Zorbax SB‐C₁₈ column (2.1 × 100 mm, 3.5 μm), using a mobile phase of acetonitrile–0.05% formic acid in 5 mm ammonium acetate buffer (70:30, v /v). A triple quadrupole mass spectrometer with positive ionization mode was used for the determination of target analytes. Under the optimized conditions, the calibration curves showed good linearity in the range of 0.1–10,000 μg/L with satisfactory limit of detection (≤0.06 μg/L) and limit of quantitation (≤0.3 μg/L). The proposed method also showed acceptable intra‐ and inter‐day precisions for ketoconazole and voriconazole from urine and human plasma with RSD ≤16.5% and good relative recoveries in the range 84.3–114.8%. The MCM‐41‐D‐μ‐SPE method proved to be rapid and simple and requires a small volume of organic solvent (200 μL); thus it is advantageous for routine drug analysis.     

Dispersive admicelle solid‐phase extraction based on sodium dodecyl sulfate coated Fe3O4 nanoparticles for the selective adsorption of three alkaloids in Gegen‐Qinlian oral liquid before high‐performance liquid chromatography

A novel dispersive admicelle solid‐phase extraction method based on sodium dodecyl sulfate‐coated Fe₃O₄ nanoparticles was developed for the selective adsorption of berberine, coptisine, and palmatine in Gegen‐Qinlian oral liquid before high‐performance liquid chromatography. Fe₃O₄ nanoparticles were synthesized by a chemical coprecipitation method and characterized by using transmission electron microscopy. Under acidic conditions, the surface of Fe₃O₄ nanoparticles was coated with sodium dodecyl sulfate to form a nano‐sized admicelle magnetic sorbent. Owing to electrostatic interaction, the alkaloids were adsorbed onto the oppositely charged admicelle magnetic nanoparticles. The quick separation of the analyte‐adsorbed nanoparticles from the sample solution was performed by using Nd‐Fe‐B magnet. Best extraction efficiency was achieved under the following conditions: 800 μL Fe₃O₄ nanoparticles suspension (20 mg/mL), 150 μL sodium dodecyl sulfate solution (10 mg/mL), pH 2, and vortexing time 2 min for the extraction of alkaloids from 10 mL of diluted sample. Four hundred microliters of methanol was used to desorb the alkaloids by vortexing for 1 min. Satisfactory extraction recoveries were obtained in the range of 85.9–120.3%, relative standard deviations for intra‐ and interday precisions were less than 6.3 and 10.0%, respectively. Finally, the established method was successfully applied to analyze the alkaloids in two batches of Gegen‐Qinlian oral liquids.     

Establishment of pressurized liquid extraction followed by HPLC–MS/MS method for the screening of adrenergic drugs,steroids, sedatives,colorants and antioxidants in swine feed

A facile and sensitive multi‐residue detection approach of pressurized liquid extraction following high‐performance liquid chromatography tandem mass spectrometry was established to detect the residues of adrenergic drugs, steroids, sedative, colorant and antioxidant in feed. The conditions employed for pressurized liquid extraction involved acetonitrile/ethyl acetate (1:1, v/v) as the extracting solvent, the temperature 80°C, two cycles and a static time of 10 min. The extraction was followed by a solid‐phase extraction clean‐up step. The separation of samples was done by C₁₈ column with the mobile phase of 5 mM ammonium acetate solution and acetonitrile with 0.1% formic acid. The limits of quantification ranged from 0.03 to 1 μg/kg, limits of detection were in a range of 0.01–0.5 μg/kg, and average recoveries were 70.4–98.6%. The pressurized liquid extraction procedure was optimized and overall method was validated in terms of sensitivity, linearity, selectivity, matrix effect, accuracy, recovery and stability of the target drugs in the pressurized liquid extraction extracts solution. The screening method was proved to be fast, selective, accurate and sensitive for screening drugs.     

Determination of a novel paclitaxel derivative (NPD‐103) in human plasma by ultra‐performance liquid chromatography–tandem mass spectrometry

A sensitive and specific ultra‐performance liquid chromatography–tandem mass spectrometry (UPLC‐MS‐MS) method for quantification of a newly developed anticancer agent NPD‐103 has been established. An aliquot of human plasma sample (200 µL) was spiked with ¹³C‐labeled paclitaxel (internal standard) and extracted with 1.3 mL of tert‐butyl methyl ether. NPD‐103 was quantitated on a C₁₈ column with methanol–0.1% formic acid (75:25, v/v) as mobile phase using UPLC‐MS‐MS operating in positive electrospray ionization mode with a total run time of 3.0 min. For NPD‐103 at the concentrations of 1.0, 5.0 and 10.0 µg/mL in human plasma, the absolute extraction recoveries were 95.58, 102.43 and 97.77%, respectively. The linear quantification range of the method was 0.1–20.0 µg/mL in human plasma with linear correlation coefficients greater than 0.999. The intra‐ and inter‐day accuracy for NPD‐103 at 1.0, 5.0 and 10.0 µg/mL levels in human plasma fell into the ranges of 95.29–100.00% and 91.04–94.21%, and the intra‐ and inter‐day precisions were in the ranges of 8.96–11.79% and 7.25–10.63%, respectively. This assay is applied to determination of half‐life of NPD‐103 in human plasma. Copyright © 2008 John Wiley & Sons, Ltd.     

A novel ultra high‐performance liquid chromatography‐tandem mass spectrometry method for the simultaneous determination of xanthones and steroidal saponins in crude and salt‐processed Anemarrhenae Rhizoma aqueous extracts

We established a rapid and sensitive ultra high‐performance liquid chromatography tandem mass spectrometry method for the simultaneous quantification of xanthones and steroidal saponins in rat plasma. Chromatographic separation was achieved on a C₁₈ column with a mobile phase comprising acetonitrile and 0.1% formic acid. The detection was performed by negative electrospray ionization in multiple reaction monitoring mode. The validated method showed good linearity within the tested range (r > 0.9945). The intra‐ and interday precision at high, medium, and low concentrations was less than 7.96%. The bias of accuracies ranged from −1.92 to 9.62%. The extraction recoveries of the compounds ranged from 84.78 to 88.69%, and the matrix effects ranged from 96.76 to 108.59%. This method was successfully applied to a pharmacokinetic comparison of crude and salt‐processed Anemarrhenae Rhizoma aqueous extracts after oral administration in rats. The maximum plasma concentration and area under concentration–time curve of timosaponin BIII and timosaponin AIII increased significantly (P < 0.05 or 0.01) and those of timosaponin BII decreased significantly (P < 0.05) after processing. These results could contribute to the clinical application of crude and salt‐processed Anemarrhenae Rhizoma and reveal the processing mechanism.     

Silica‐based magnetic hybrid nanocomposite for the extraction and preconcentration of some organophosphorus pesticides before gas chromatography

The precise control of pesticide residues in foodstuffs depends significantly on the clean extraction of analytes using specifically designed separation methods. In this study, a one‐pot sol–gel process was used for the preparation of a magnetic hybrid silica gel tetraethylortho silicate‐cyanopropyltriethoxy silane nanocomposite. The prepared material was characterized using energy dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy, single‐point specific surface area, and scanning electron microcopy. The synthesized magnetic hybrid material was used as a solid phase extraction sorbent for the extraction and preconcentration of some organophosphorus pesticides before gas chromatography with a microelectron capture detector. The performance of the proposed magnetic solid‐phase extraction technique was validated by linearity (0.05–2 ng/mL), correlation coefficients (r² = 0.9993–0.9997), limit of detection (0.02–0.06 ng/mL, S/N = 3, n = 3), and intraday (RSD = 1.5–8.7%, n = 3) and interday precision (RSD = 5.5–9.3%, n = 12), while the recovery in real samples and equilibrium adsorption capacity was 72.02–103.84% and 8–20 mg/g, respectively. The magnetic solid‐phase extraction based on the hybrid nanocomposite revealed a high enrichment factor, an appropriate dynamic range, and great absorptive ability toward the selected organophosphorus pesticides spiked in real water samples.     

Rapid extraction and analysis method for the simultaneous determination of 21 bioflavonoids in Siegesbeckia pubescens Makino

A novel and rapid microwave extraction and ultra high performance liquid chromatography coupled with a triple quadrupole‐linear ion trap mass spectrometry method was developed and validated for the determination of 21 bioflavonoids in Siegesbeckia pubescens Makino. The optimal conditions for the extraction of flavonoids from Siegesbeckia pubescens Makino involved the use of methanol as the extraction solvent, a microwave temperature of 70°C, an extraction time of 11 min, and a solvent‐to‐solid ratio of 40 mL/g. Chromatographic separation was achieved on a Waters ACQUITY UPLC BEH C₁₈ column(100 × 2.1 mm, 1.7 μm) with a gradient mobile phase (A: 0.3% v/v aqueous formic acid and B: acetonitrile) at a flow rate of 0.25 mL/min. All calibration curves showed good linearity (r > 0.999) within the test ranges. The method developed was validated with acceptable sensitivity, intra‐ and interday precision, reproducibility, and extraction recoveries. The validated method was successfully applied to determine the contents of 21 bioflavonoids in Siegesbeckia pubescens Makino from different sources.     

Detection of 13 mycotoxins in feed using modified QuEChERS with dispersive magnetic materials and UHPLC–MS/MS

An analytical method for the simultaneous determination of 13 mycotoxins in feed by magnetic dispersive solid‐phase extraction combined with ultra‐high performance liquid chromatography and tandem mass spectrometry was developed. The samples were extracted with acetonitrile/water (80:20, v/v, containing 3% acetic acid), and separated by centrifugation after salting‐out, and then treated with magnetic adsorbents to remove interferences. The separation of target mycotoxins was performed on an ACQUITY UPLC HSS T3 column using a mobile phase consisting of 1 mmol/L ammonium acetate with 0.1% formic acid and methanol by gradient elution. Good linearities for the 13 mycotoxins were achieved with correlation coefficients over 0.99, and the recoveries of mycotoxins were in the range of 89.3–112.6% at spiking at levels of 5, 20, and 100 μg/kg, with relative standard deviations of 0.9–10.4%. Based on the functional magnetic materials (MDN@Fe₃O₄, PSA@Fe₃O₄, ZrO_2@Fe₃O₄) applied in dispersive solid‐phase extraction, the pretreatment process is more convenient and it is beneficial to reduce the experimental cost by reusing the recycled magnetic materials. It is a simple, rapid, and environmentally friendly analytical method for the determination of mycotoxins in feed.