Fast determination of multi-mycotoxins in corn by dispersive solid-phase extraction coupled with ultra-performance liquid chromatography with tandem quadrupole time-of-flight mass spectrometry

A fast analytical method for the simultaneous determination of 9 mycotoxins, including alfatoxins （B1, B2, G1, and G2）, fumonisins （B1, B2 and B3）, zearalenone, and deoxynivalenol in corn using dispersive solid-phase extraction method and ultra-performance liquid chromatography coupled to tandem quadrupole time-of-lfight mass spectrometry （UPLC-Q-TOF-MS） was developed and validated. Samples were extracted with acetonitrile-water （84：16, v：v, containing 1% acetic acid） using ultrasonic extraction. The extracts were puriifed with a dispersive SPE method using C18 as a cleaning agent. The ifnal clear extracts were dried by nitrogen blowing and subsequently redissolved in methanol-water （5：5, v：v）. The samples were then analyzed by UPLC-Q-TOF-MS with 0.1% formic acid in ammonium acetate-methanol as mobile phase. The mean recoveries were ranged from 68.0 to 120.0%, and the relative standard deviation （RSD） ranged from 0.18 to 6.29%. Limits of detections ranged from 0.05 to 50 μg kg？1, and limits of quantiifcation ranged from 0.1 to 200 μg kg？1, which were below the legal limits set by the European Union for the legislated mycotoxins. The developed method was applied to 130 corn samples. Among the mycotoxins studied, alfatoxins B1 and fumonisins B1, B2 and B3 were the most predominant mycotoxins, and their concentrations were 0–593.12, 0–2.01×104, 0–6.94×103 and 0–3.05×103 μg kg–1, respectively.

Trace determination and characterization of ginsenosides in rat plasma through magnetic dispersive solid-phase extraction based on core-shell polydopamine-coated magnetic nanoparticles

Enrichment of trace bioactive constituents and metabolites from complex biological samples is challenging.This study presented a one-pot synthesis of magnetic polydopamine nanoparticles(Fe3O4@-SiO2@PDA NPs)with multiple recognition sites for the magnetic dispersive solid-phase extraction(MDSPE)of ginsenosides from rat plasma treated with white ginseng.The extracted ginsenosides were characterized by combining an ultra-high-performance liquid chromatography coupled to a highresolution mass spectrometry with supplemental UNIFI libraries.Response surface methodology was statistically used to optimize the extraction procedure of the ginsenosides.The reusability of Fe3O4@-SiO2@PDA NPs was also examined and the results showed that the recovery rate exceeded 80%after recycling 6 times.Furthermore,the proposed method showed greater enrichment efficiency and could rapidly determine and characterize 23 ginsenoside prototypes and metabolites from plasma.In comparison,conventional methanol method can only detect 8 ginsenosides from the same plasma samples.The proposed approach can provide methodological reference for the trace determination and characterization of different bioactive ingredients and metabolites of traditional Chinese medicines and food.

Matrix Solid-phase Dispersion Extraction of Alkaloids from the Roots of Aconitum kusnezoffii Reichb

Matrix solid-phase dispersion（MSPD） was developed for the extraction of four alkaloids, including aconitine, mesaconitine, hypaconitine and deoxyaconitine, from the roots ofAconitum kusnezoffii Reichb. The determination of the analyte was carried out by high performance liquid chromatography with UV detection. The alkaline alumina was used as sorbent. The mixture of acetonitrile and water was used as elution solvent. Several extraction parameters, such as type of sorbent, the ratio of sample to solid support material, type of the elution solvent and the volume of the elution solvent were tested. Mean recoveries ranged from 93.16% to 102.73%, with relative standard deviations from 0.27% to 4.17%. With the extraction efficiency and time expenditure taken into account, MSPD extraction should be a comparatively good method.

Optimization and Application of Liquid Chromatography Determination of Dispersive Liquid-liquid Microextraction Purified Astaxanthin in Shrimp Waste

A new molecularly imprinted solid-phase extraction（MISPE） monolithic cartridge was synthesized, and MISPE-DLLME（DLLME=dispersive liquid-liquid microextraction） was developed for purification of astaxanthin in shrimp waste. The eluent（methanol） from MISPE was used as the dispersive solvent in subsequent DLLME for further purifying and enriching the analyte prior to high-performance liquid chromatography（HPLC） analysis. The mobile phase was methanol-acetonitrile-water-dichloromethane（85：5：5：5, volume ratio）, flow rate was 0.7 mL/min and UV wavelength was 476 nm. Under optimal conditions, good linearity was obtained in a range of 0.2--200.0 lug/mL（r2=0.9998） with a limit of detection（LOD） of 0.08 Hg/mL, and the extraction recoveries at three spiked levels ranged from 88.3%--92.5% with a relative standard deviation（RSD） less than 4.3%. Moreover, the mean contents of astaxanthin in the three batches of shrimp waste were 95.9, 85.4 and 77.2 μg/g, respectively. This method combining the advantages of MISPE and DLLME results in high selectivity and low cost, which was applied to determining the astaxanthin level in shrimp waste samples.

Constructing cactus-like mixed dimensional MOF@MOF as sorbent for extraction of bisphenols from environmental water

Metal-organic frameworks(MOFs)received considerable attention to adsorption and removal of various environmental pollutants because of some inherent advantages.However,it is challenging but meaningful to design and fabricate hierarchical mixed-dimensional MOFs with synergistic effects to enhance the performance for removal and preconcentration of environmental pollutants.Herein,a new hierarchical two-dimensional(2D)-three-dimensional(3D)mixed-dimensional cactus-like MOF@MOF hybrid material(PCN-134@Zr-BTB)was prepared by in-situ growth of 2D MOF nanosheets(Zr-BTB)on the surface of 3D MOF(PCN-134).The PCN-134@Zr-BTB composites combine the advantages of 2D and 3D MOFs with extensive mesoporous structures and large surface area for effective removal and enrichment of bisphenols(BPs).In comparison with pristine PCN-134 and Zr-BTB materials,the PCN-134@Zr-BTB hybrid material presented excellent adsorption performance for BPs.The adsorption isotherms are consistent with the Langmuir model,and the maximum adsorption capacity of four bisphenols(BPs)ranged from 135.1 mg/g to 628.9 mg/g.The adsorption kinetics are in accordance with the pseudo-second-order model.The recoveries ranged from 72.8%to 108%.The limits of detection were calculated at 0.02-0.03 ng/mL.The enrichment factors were calculated in the range of 310-374.According to FT-IR and XPS analysis,the main adsorption mechanisms are hydrogen bonding and π-π stacking.Nevertheless,this work provides a new and convenient strategy for the preparation of new hierarchical mixed-dimensional MOF@MOF(PCN-134@Zr-BTB)hybrid material for extraction and enrichment of BPs from aqueous matrix.

分散固相萃取法对鸡精中3-氯-1,2-氯丙醇的测定

A new method for determination of 3-MCPD in powder condiments was established by GC-MS method using 1,4-butanediol as an internal standard.Samples were ultrasonically extracted by ethyl acetate,and cleaned up by dispersive solid-phase extraction(d-SPE) using octadecane sorbent(C18).Then the extract was derivatized with HFBI and detected by GC-MS.The detection limitation was 1.0 μg/kg,and spiked recoveries ranged from 97%-102% with RSD of 2.1%-4.1%.

Development and validation of an analytical method for detecting chlorantraniliprole residues in fresh tea leaves

An efficient method using multiwalled carbon nanotubes(MWCNTs)as dispersive solid-phase extraction sorbent was established for determining chlorantraniliprole residues in fresh tea leaves,which are known to be a troublesome matrix containing abundant pigments,via gas chromatography with an electron capture detector.Acetonitrile was used as the extraction solvent,with sodium chloride enhancing the analyte partition in the organic phase.The optimal mixture of MWCNTs and primary secondary amine(PSA)was based on the distribution of the target analyte recovery and on the clean-up efficiency;while matrix-matched calibration was recommended to combat the matrix effect.Mean recoveries of 95.2%–108.8%were obtained with intraday and interday precisions of less than 7.9%and 10.3%,respectively.Good linearity was observed for concentrations of 0.02–1.0 mg/kg with a correlation coefficient of 0.9984.The limits of detection and quantification were 0.005 mg/kg and 0.02 mg/kg,respectively.The method was employed to investigate the dissipation dynamics of chlorantraniliprole in fresh tea leaves with real field samples.Consequently,the dissipation rates of chlorantraniliprole in fresh tea leaves followed pseudo-first-order kinetics with a half-life of 1.9 d,and the average chlorantraniliprole residue content was below 0.02 mg/kg with a harvest withholding period of 14 d.

Facile preparation of nano-g-C_(3)N_(4)/UiO-66-NH_(2) composite as sorbent for high-efficient extraction and preconcentration of food colorants prior to HPLC analysis

In this work,the nano-g-C_(3)N_(4)/Ui O-66-NH_(2)composite was prepared by one-step solvothermal method.The as-prepared composite was characterized by scanning electron microscopy,Brunner-Emmet-Teller measurement,energy dispersive spectrometer,X-ray diffraction,and Fourier transform infrared spectroscopy.By using nano-g-C_(3)N_(4)/Ui O-66-NH_(2)composite as sorbent,a dispersive solid-phase extraction coupled with high-performance liquid chromatography was developed to sensitive analysis of food colorants including tartrazine,amaranth,carmine,sunset yellow,allura red and bright blue.The experiment parameters including the amount of sorbent,adsorption time,the p H of adsorption solution,desorption time,desorption solvent,the p H of desorption solution as well as the proportion between desorption solvent and buffer solvent were investigated.Under the optimized conditions,the limits of detection(S/N=3) and limits of quantitation (S/N=10) were determined in the ranges of 0.08-0.8 and 0.2-2.0 ng/m L,respectively.With the developed sample pretreatment method,carmine and brilliant blue were determined from blueberry juice by HPLC-DAD.The contents were calculated as 1.53μg/m L and0.17μg/mL,respectively.

Simultaneous determination of 6 carbamate pesticides and relevant metabolites in oilseeds and oil with the modified fast QuEChERS method by ultra-performance liquid chromatography-tandem mass spectrometry

A sensitive and reliable method was developed and validated for the simu1taneous determination of 6 carbamate pesticides and relevant metabolites based on the modified fast QuEChERS(quick,easy,cheap,effective,rugged and safe)method combined with ultra-performance 1iquid chromatography-tandem mass spectrometry(UPLC-MS/MS).The method was also applied in the analysis of 23 commonly consumed oilseeds and oil samples.The sample was extracted with acetonitrile for three times and then the extracted solution was filtered directly though 250 mg precipitated silica adsorbent(PSA)and 250 mg Cis The mobile phase was water(containing 0.1%formic acid)and acetonitrile.The extemal standard protocols were adopted to validate the method in terms of recovery,1inearity,precision,sensitivity,and relative standard deviation(RSD)under the optimized conditions.The linear calibration curves with different ranges were established with R^(2)>0.9973,limit of detections(LODs)ranged from 0.100μg/kg to 20000μg/kg and limit of quantitations(LOQs)ranged from 0.300μg/kg to 6.000μg/kg.The LODs meets the detection requirement for the maximum residue limits in practical samples.Meanwhile,the recoveries ranged from 60.2%to 116.6%with associated RSDs ranged from 0.33%to 5.35%in 10 oilseeds matrices and ranged from 61.9%to 116.9%with RSDs ranged from 0.30%to 5.02%in 13 oil matrices.These features do make the UPLC-MSMS an ideal analytical platform for accurate and high throughput analysis of carbamates residues in the complex matrix.

腐植酸改性磁性纳米材料分散固相萃取-高效液相色谱法在尿苯巯基尿酸检测中的应用

目的建立腐植酸改性磁性纳米材料分散固相萃取结合高效液相色谱测定尿中苯巯基尿酸（S—phenylmercapturic acid，SPMA）的前处理方法。方法5ml尿样用盐酸调节pH为1．0，采用腐植酸改性磁性纳米材料（Fe3O4@HA）进行分散固相萃取，EC—C18色谱柱分离，高效液相色谱分析，紫外检测器检测，以保留时间定性，峰面积和外标法定量。结果苯巯基尿酸（SPMA）线性范围为0．04—1．00mg／L，相关系数为0．9997，以3倍信噪比估算方法检出限为0．012mg／L，加标回收率为94．2％～102．4％，批内、批间精密度分别为2．9％～6．7％、3．1％～7．5％。结论本方法前处理过程简便快捷，灵敏度和准确度较高，可用于职业接触苯人群尿中苯巯基尿酸的测定。

基于硅藻土改性的磁性纳米材料分散固相萃取-高效液相色谱法测定尿中苯巯基尿酸

目的建立硅藻土改性磁性纳米材料分散固相萃取-高效液相色谱测定尿中苯巯基尿酸。方法尿样经过离心后,取5. 0 ml上清液,用盐酸调节pH值为1. 0,经硅藻土改性磁性纳米材料进行分散固相萃取后,分离出有机相,残渣用甲醇溶解并定容后注入高效液相色谱仪,经EC-C18反相色谱柱(150 mm×4. 6 mm,4μm)分离,紫外检测器检测,以保留时间定性,峰面积外标法定量。结果本法中苯巯基尿酸在0. 050 mg/L～1. 0 mg/L内线性关系良好,相关系数为0. 999 7,以3倍噪音值计算方法检出限为0. 028 mg/L,在0. 050 mg/L～1. 0 mg/L内添加低、中、高3个浓度水平,样品加标回收率为94. 9%～108. 0%,批内精密度和批间精密度分别为4. 6%～9. 8%(n=6)与4. 3%～8. 9%(n=6)。结论本方法简便快捷,分析时间短,灵敏度高,可用于职业接触苯人群尿中苯巯基尿酸的检测。