Degradation Dynamics and Residue Analysis of Flubendiamide in Cabbage and Soil by Liquid Chromatography-Tandem Mass Spectrometry with Dispersive Solid Phase Extraction

To formulate a scientific basis for a reasonable spray dose and safe interval period of 20% flubendiamide water dispersible granule (WDG) on controlling vegetable pests, degradation dynamics of flubendiamide in cabbage and soil was analyzed in this study. Dissipation and residue of flubendiamide in 20% flubendiamide WDG in cabbage and soil under field conditions were investigated by liquid chromatography-tandem mass spectrometry with dispersive solid phase extraction. Results showed that the degradation dynamic equations of flubendiamide in cabbage and soil were based on the first-order reaction dynamic equations. The half-lives of the degradation of flubendiamide were 3.51 d to 3.96 d and 3.43 d to 3.87 d in the cabbage of Yangzhou and Jingzhou, respectively, and 4.42 d to 5.13 d and 4.37 d to 4.99 d in the soil of Yangzhou and Jingzhou, respectively. The terminal residues of flubendiamide in the cabbage of Yangzhou and Jingzhou were 0.0247 mg·kg-1 to 0.0393 mg·kg-1 and 0.0225 mg·kg-1 to 0.0273 mg·kg-1, respectively, when 20% flubendiamide WDG was applied at a dose of0.050g·m-2. Flubendiamide is safe to be applied in cabbage fields at the recommended dose.

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.

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.

Determination of N-Methylcarbamate Pesticides in Vegetables by Solid-phase Extraction and Pressurized Capillary Electrochromatography

Capillary electrochromatography （CEC） is a hybrid technique that couples the good selectivity of high-performance liquid chromatography （HPLC） and the high separation efficiency of capillary electrophoresis （CE）. Both charged and uncharged compounds can be separated effectively using CEC. In some cases, however, the bubbles that generated in the capillary column in pure CEC performed on commercial CE instruments will cause unstable current and even disrupt the separation when the concentration of buffer is very high. By applying pressure on the electrochromatographic separation via a micro-HPLC pump, pressurized capillary electrochromatography （ pCEC ） combines two driving factors of the electroosmotic flow （EOF） and the pressure flow, thereby increasing the speed and the selectivity of separation and suppressing the bubble formation. Moreover,

Determination of organochlorine pesticides from juice samples using magnetic biochar-based dispersive micro-solid phase extraction in combination with dispersive liquid-liquid microextraction

Analysis of pesticide residue levels in juice beverages is important to ensure safe consumption and avoid global trade concerns associated to pesticide contaminations.A simple,inexpensive and effective method was developed for the determination of organochlorine pesticides(OCPs)in bottled juice drinks using GC-MS.Sample pretreatment was performed using dispersive solid-phase microextraction(D-μ-SPE)for matrix desorption and dispersive liquid-liquid microextraction(DLLME)for analyte enrichment.In this study,an affordable and effective sorbent for the adsorption of OCPs from juice samples was synthesized from avocado seeds mixed with magnetic precursors for D-μSPE.The ground avocado seeds combined with a magnetic precursor nanocomposite were characterized using various instruments including scanning electron microscopy(SEM),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and Brunauer-Emmett-Teller(BET)analysis.The solution obtained from D-μ-SPE desorption was used as a dispersant for the subsequent DLLME,which made the combination of D-μ-SPE with DLLME much easier.The effectiveness of the method was enhanced by optimizing the influential parameters in both D-μ-SPE and DLLME.Then after,the optimal values were determined for the real sample analysis.Accordingly,there was good linear dynamic range with a coefficient of determination(r2)≥0.9989.The limit of detection and quantification were 0.02–0.69 and 0.06–2.10 ng/L respectively.The method showed high enrichment factors ranging from 96 to 313 with recoveries of 87–100%.Intraday and interday precisions were≤4%.Compared with other reported methods,this method is a one-step,simple,cheap,fast,and environmentally friendly alternative and straightforward method for adsorbing organochlorine pesticides from sample solutions.These results demonstrates the high potential of the proposed method for the extraction and cleanup of contaminants in selected juices and other related samples.

Preparation of ferric oxide-aluminium oxide carbon nanofiber nanocomposites for ultrasound-assisted dispersive magnetic solid phase extraction of 17-beta estradiol in wastewater

In this work,Fe3O4-Al2O3@CNFs nanocomposite was synthesised and used as a nanosorbent in the ultrasound-assisted dispersive magnetic solid phase extraction(UA-DMSPE)of 17-beta estradiol(E2)in wastewater samples.The quantification of E2 was achieved using high performance liquid chromatography coupled with diode array detector(HPLC-DAD).Various parameters affecting the efficiency of this sample preparation technique were optimised to achieve excellent sensitivity and high recoveries of E2.Response surface methodology was utilised for optimisation of these parameters.Using the optimised conditions,the linear dynamic range was achieved in the range of 0.1e1000 mgL^-1and the correlation coefficient was found to be 0.9981.The preconcentration factor,enrichment factor,limit of detection(LOD)and limit of quantification(LOQ)were 67,169,0.025 mgL^-1and 0.083 mg L1,respectively.The relative standard deviation(%RSD)for the intraday(n?10)and interday(n?5 working days)were 1.8%and 3.3%,respectively.The developed UA-DMSPE/HPLC-DAD method was applied for the preconcentration and determination of E2 in wastewater samples.The obtained results indicated that E2 was present in the wastewater samples.

分散固相萃取净化-GC-MS法测定橡胶中N-亚硝基二乙基胺

分别考察了萃取溶剂的选择,吸附剂C18和PSA用量。将样品剪成约1cm×1cm左右的碎片并冷冻粉碎,过18目分样筛。样品用10mL二氯甲烷,在30℃条件下超声30min,萃取液经100mg吸附剂C18和100mg PSA净化,离心。上清液用毛细管色谱柱DB-WAX(30m×0.32mm×0.50μm)分离,采用GC/MS选择离子检测,外标法定量。结果表明:N-亚硝基二乙基胺在0.05~4.00mg/L的浓度范围内,线性良好,相关系数(r)为0.9994,方法检出限(LOD)和定量限(LOQ)分别为0.5mg/kg和1.0mg/kg;加标平均回收率在90.2%~98.6%之间,相对标准偏差RSD在2.3%~6.8%之间。该方法样品前处理简单,分析速度快。

Synthesis of a Novel Imidazole Ionic Liquid Modified Mesoporous Silica SBA15 for Selective Separation and Determination of Inorganic Arsenic in Rice

A novel 1-methylimidazole ionic liquid modified SBA15 mesoporous silica(1-MIIL@SBA15) was synthesized and applied to selective separation of inorganic arsenic(iAs) in rice by dispersive solid phase extraction(DSPE), followed by hydride generation-atomic fluorescence spectrometric(HG-AFS) quantification. The prepared sorbent was characterized by FTIR, FESEM, BET and Zeta potential. Key parameters of adsorption and desorption in DSPE were optimized using standard reference material 1568 b rice flour. Under optimal conditions, the limit of detection was 8.776 ng/kg, relative standard deviation was ≤2.0%, and recoveries of iAs were in the 92.3～94.4% range. This method was successfully applied to the determination of iAs in rice. Under acidic condition, the electrostatic interaction between the positively charged 1-MIIL@SBA15 and anionic iAs played an important role in selective iAs separation, rendering this method suitable for iAs analysis.

活性炭固相萃取-气相色谱-质谱法检测人尿中N,N-二甲基乙酰胺和N-甲基乙酰胺

建立了活性炭固相萃取-气相色谱-质谱同时测定尿中N,N-二甲基乙酰胺与N-甲基乙酰胺的气相色谱-质谱测定方法。在pH 7.0条件下,以活性炭固相萃取小柱萃取、净化,以甲醇洗脱,采用Innowax毛细管柱分离,选择离子检测。结果表明,N,N-二甲基乙酰胺和N-甲基乙酰胺线性范围在0.10～40.0 mg/L,相关系数分别为0.9997和0.9995;在空白尿样中分别添加低中高3个浓度水平,N,N-二甲基乙酰胺和N-甲基乙酰胺回收率分别为94.7%～102.6%和96.6%～101.2%,相对标准偏差均小于5.5%;以3倍性噪比计算检出限,N,N-二甲基乙酰胺和N-甲基乙酰胺检出限分别为0.01和0.03 mg/L。本方法精确、稳定、灵敏度高,可用于尿中N,N-二甲基乙酰胺和N-甲基乙酰胺的测定。

气相色谱-质谱联用法测定传统腌菜中的N-亚硝胺

建立了气相色谱-质谱（GC-MS）快速测定腌制蔬菜中N-亚硝胺含量的分析方法。采用固相萃取（SPE）结合GC/MS检测了N-二甲基亚硝胺（NDMA）、N-二乙基亚硝胺（NDEA）,考察了样品不同提取方法、不同固相萃取洗脱剂配比对分离效果的影响。结果表明,固相萃取相较于超声萃取,回收率高且峰图干净,而固相萃取中选用90%的甲醇水溶液作为洗脱剂,不仅回收率均可达90%以上,同时也减少了有机溶剂的使用量,优化后两种N-亚硝胺的线性范围均为0.1-10.0 mg/L;相关系数分别达到0.994和0.999;检出限为0.02 mg/L;回收率为90%-112%;相对标准偏差（RSD）均小于2.3%,重现性良好。该方法前处理简便、快速,易于操作,适合各类腌制蔬菜中N-亚硝胺的检测。

Solid Phase Extraction of Trace Copper（Ⅱ） Using Octadecyl Silica Membrane Disks Modified with N,N′-Disalicylideneethylenediamine

A simple and reproducible method for the rapid extraction and determination of trace amounts of copper（Ⅱ） ions using octadecyl-bonded silica membrane disks modified by N,N′-disalicylideneethylenediamine （DESDA） and atomic absorption spectrometry was presented. The method is based on complex formation on the surface of the ENVI-18 DISK^TM disks followed by stripping of the retained species by minimum amounts of appropriate organic solvents. The elution is efficient and quantitative. The effects of potential interfering ions, pH, ligand amount, stripping solvent, and sample flow rate were also investigated. Under the optimal experimental conditions, the break-through volume was found to about be 1000 mL providing a preconcentration factor of 500. The maximum capacity of the disks was found to be （389±4） μg for Cu^2＋. The limit of detection of the proposed method is 5 ng per liter. The method was applied to the extraction and recovery of copper in different water samples.

Accurate and sensitive determination of hydroxychloroquine sulfate used on COVID-19 patients in human urine,serum and saliva samples by GC-MS

A rapid,accurate,and sensitive analytical method,ultrasonication-assisted spraying based fine droplet formationeliquid phase microextractionegas chromatographyemass spectrometry(UA-SFDF-LPME-GCMS),was proposed for the determination of trace amounts of hydroxychloroquine sulfate in human serum,urine,and saliva samples.To determine the best extraction strategy,several liquid and solid phase extraction methods were investigated for their efficiencies in isolation and preconcentration of hydroxychloroquine sulfate from biological matrices.The UA-SFDF-LPME method was determined to be the best extraction method as it was operationally simple and provided accurate results.Variables such as the extraction solvent,spraying number,sodium hydroxide concentration and volume,sample volume,mixing method,and mixing period were optimized for the proposed method using the onevariable-at-a-time approach.In addition,Tukey’s method based on a post hoc comparison test was employed to evaluate the significant difference between the parameters inspected.After the optimization studies,the limit of detection(LOD)and limit of quantification(LOQ)were determined to be 0.7 and 2.4 mg/kg,respectively.The sensitivity of the GC-MS system based on the LOD was enhanced approximately 440-fold when the UA-SFDF-LPME method was employed.Spiking experiments were also conducted for the human serum,urine,and saliva samples to determine the applicability and accuracy of the proposed method.Recoveries for the human serum,urine,and saliva samples were found to be in the ranges of 93.9%-101.7%,95.2%-105.0%,and 93.1%-102.3%,respectively.These results were satisfactory and indicated that the hydroxychloroquine sulfate level in the above biological samples could be analyzed using the proposed method.

气相色谱-正化学源质谱法测定橡胶中N-亚硝胺及其前体物的迁移量

从样品前处理和仪器分析方法两方面对欧盟标准EN 12868:1999中N-亚硝胺及其前体物的测试方法进行了改进,使其更适合批量样品的快速精确分析。用人工唾液浸泡橡胶制品,模拟其接触人体过程中N-亚硝胺的析出过程,再用Sep-Pak AC2串联Sep-Pak Dry固相萃取小柱对人工唾液中的N-亚硝胺分析物进行萃取净化,最后用DB 624毛细管气相色谱柱对其进行分离,正化学源质谱在全扫和单扫两种模式下进行分析。7种N-亚硝胺在10～10000μg/L浓度范围内呈良好线性关系,相关系数R均大于0.99;对橡胶中N-亚硝胺及其前体物的方法检出限分别为1.25和5.00μg/kg,低于欧盟93/11/EEC的限量要求;3个加标水平1.25,12.5和125μg/kg的回收率分别为80.6%～95.5%,86.8%～98.3%和92.2%～110.4%,RSD分别为4.2%～7.7%,4.1%～5.8%和2.6%～4.3%(n=6)。分析的气球样品中,7种N-亚硝胺及其前体物的总检出含量分别为0.421～0.820 mg/kg和3.616～8.437 mg/kg,均超出欧盟93/11/EEC指令的限制要求;但分析的婴儿奶嘴样品中则均未有检出N-亚硝胺及其前体物。

SPME-GC-NPD法测定肉制品中挥发性N-亚硝胺

改进3种N-亚硝胺(N-亚硝基二乙胺,NDEA;N-亚硝基二甲胺,NDMA;N-亚硝基吡咯烷,NPYR)的测定方法。以固相微萃取(SPME)为样品萃取方式,配备氮磷检测器的气相色谱仪(GC-NPD)为检测工具,研究3种N-亚硝胺(NDEA、NDMA、NPYR)的测定方法。以PDMS/DVB/CAR为萃取头,萃取温度50℃、搅拌速度400 r/min、萃取时间30 min、盐离子浓度0.20 g/m L时NDEA能得到最大的萃取面积。对3种N-亚硝胺的线性分析得出,NDEA的测定在10 ng/m L^100 ng/m L时线性关系为0.994;NDMA在10 ng/m L^100 ng/m L时的线性关系为0.912;NPYR在0~10 ng/m L时没有表现出明显线性关系。采用SPME,结合GC-NPD测定N-亚硝胺的方法,对NDEA的测定灵敏度最高,RSD为6.7%,加标回收率为89.7%,最低检出限(LOD)0.67 ng/m L,可以满足肉制品中NDEA的定量测定。

固相萃取-气相色谱-串联质谱法测定乳胶儿童用品中15种N-亚硝胺及其前体物的迁移量

建立了同时测定乳胶儿童用品中15种Ⅳ．亚硝胺及其前体物迁移量的固相萃取-气相色谱-串联质谱（SPE-GC—MS／MS）分析方法。以人工唾液作为迁移模拟物，以ChromabondEasy固相萃取柱（填料的主要成分是极性修饰的聚乙烯-二乙烯基苯共聚物）对迁移液中的N-亚硝胺分析物进行净化，采用HP一5MSUI色谱柱分离，MS／MS在多反应监测模式下进行定性及定量分析。15种N-亚硝胺在5～2000μg／L范围内呈良好的线性关系，相关系数均大于0．998；方法定量限（S／N：10）为0．625-12．50μg/kg，低于欧盟2009／48／EC指令的限量要求。在低、中、高3个添加水平的回收率为53．8％-116．2％、52．7％～105．1％和49．5％～102．9％；日内精密度分别为1．3％-14.0％（n=6），目间精密度为1．6％-7．6％（n=4）。采用本方法对婴儿奶嘴样品和气球样品进行了测定，其中4件奶嘴和7件气球样品中检出亚硝胺及其前体物，奶嘴和气球中N-亚硝胺的总检出含量分别为0．0499～0．126mg／kg和0．515～41．2mg／kg；N-亚硝胺前体物总检出量分别为0．0264～0．0300mg／kg和0．187～12．5mg／kg。

固相萃取-高效液相色谱柱后衍生法测定水中痕量N-甲基氨基甲酸酯

目的：建立简便、灵敏、准确的测定水中11种痕茸N-甲基氨基甲酸酯类农药及其代谢产物的固相萃取、高液相色谱柱后衍生的检测方法。方法：水样经ODS—C18小柱富集、净化后，以甲醇／TL／乙腈为流动相，在Waters氨基甲酸酯类农药分析专用柱（3．9mm×150mm）上进行梯度洗脱分离，然后再在碱性条件下（pH〉9．0），采用2-巯基乙醇和邻苯二甲醛（OPA）进行柱后衍生，荧光法检测（λex339nm，λem445nm）。结果：11种N-甲基氨基甲酸酯类农药及其代谢产物在50．0—1500．0μg／L范围内均具有良好的线性，水样的定量检测下限为0．10—0．73μg／L，方法回收率在91．5％～104．1％，RSD均小于7．6％。结论：该法灵敏度高、操作简便、快速，适用于实际样品的测定。

SPME-GC-NPD法测定肉制品中挥发性N-亚硝胺的条件优化

利用固相微萃取(solid-phase microextraction,SPME)结合气相色谱-氮磷检测器(gas chromatographynitrogen-phosphorus detector,GC-NPD)测定肉制品中9种挥发性N-亚硝胺。通过优化平衡时间、解析时间、萃取时间、萃取温度、Na Cl浓度和转速确定9种挥发性N-亚硝胺的最佳萃取条件。结果表明:以PDMS/DVB/CAR为萃取头,平衡时间10 min、萃取温度40℃、萃取时间30 min、搅拌速率400 r/min、Na Cl质量浓度0.36 g/mL、解吸时间3 min时能得到最佳萃取效果。采用SPME结合GC-NPD测定9种N-亚硝胺的线性相关系数为0.994 9~0.999 7,检出限为0.01~10.00 ng/mL,定量限为0.03~33.00 ng/mL,回收率为50.19%~93.20%,相对标准偏差(relative standard deviation,RSD)为2.29%~9.65%。该方法可以满足肉制品中N-二甲基亚硝胺(N-nitrosodimethylamine,NDMA)、N-二乙基亚硝胺(N-nitrosodiethylamine,NDEA)、N-二丙基亚硝胺(N-nitrosodipropylamine,NDPA)和N-二丁基亚硝胺(N-nitrosodibutylamine,NDBA)这4种物质含量的测定。

固相萃取-超高效液相色谱-电喷雾串联质谱法同时检测尿样中的麻黄碱和N-甲基麻黄碱

建立了固相萃取-超高效液相色谱-电喷雾串联质谱(SPE-UPLC-ESI MS/MS)联用方法,定量测定尿样中的麻黄碱和N-甲基麻黄碱。样品经Oasis MCX柱提取、纯化和富集后,采用电喷雾(ESI)离子源电离,正离子多反应监测(MRM)模式质谱进行定性和定量分析。麻黄碱和N-甲基麻黄碱在0.025 0～2.50μg/L质量浓度范围内线性关系良好,线性相关系数分别为0.999 8和0.999 2,提取回收率高于80%,提取效率的RSD小于5.0%,检出限均达到0.01μg/L,可大大延长尿样检材中麻黄碱和N-甲基麻黄碱的检测周期。结果表明,该方法快速、准确,为尿液中痕量麻黄碱和N-甲基麻黄碱的分析提供了灵敏的分析方法。

在线二维固相萃取-HPLC-MS/MS法测定卷烟侧流烟气中的TSNAs

为准确测定卷烟侧流烟气中的烟草特有N-亚硝胺,建立了检测NNN、NAB、NAT和NNK的在线二维固相萃取-高效液相色谱-串联质谱(Online 2D SPE-HPLC-MS/MS)方法。采用抗坏血酸处理的剑桥滤片和鱼尾罩捕集侧流烟气,用乙酸铵溶液淋洗鱼尾罩,将淋洗液收集到装有剑桥滤片的锥形瓶中振荡萃取,萃取液过滤后进行在线二维SPE净化和LC-MS/MS分析。结果表明:1二维SPE净化较单独使用阳离子交换柱或C18反相柱更能有效地去除样品中的杂质,降低基质效应。2优化确定的二维SPE条件:上样体积为0.8 m L(2%甲酸),速率1.0 m L/min,转移体积为0.8 m L(1%氨水),速率0.8 m L/min,阳离子交换柱洗涤液为甲醇与2%甲酸的混合溶液(体积比15∶85),C18柱洗涤液为1%氨水,洗脱时间为1.5 min。3 NNN、NAB、NAT和NNK的检出限分别为0.006、0.002、0.004和0.003 ng/m L,回收率93.4%~107.3%,精密度小于8%。该方法灵敏度高、准确性好,适用于卷烟侧流烟气中4种TSNAs释放量的检测。

固相萃取净化及超高效液相色谱-串联质谱法测定橡胶制品中的13种N-亚硝胺

建立了固相萃取（SPE）净化、超高效液相色谱-串联质谱（UHPLc—MS／MS）测定橡胶制品中13种N-亚硝胺的方法。样品于密闭萃取瓶中于60℃下用甲醇超声萃取30min，C18固相萃取小柱对萃取液进行净化，经C18色谱柱分离，最后用电喷雾正离子（ESI＋）和多重反应监测模式（MRM）对13种N-亚硝胺进行定性、定量测定。实验中对样品前处理、色谱分离条件和质谱检测条件进行了优化。在优化的实验条件下，橡胶样品中添加N-亚硝基二甲胺（NDMA）与N-亚硝基-二乙基胺（NDEA）为500μg／kg、其他组分均为50μg／kg时，各组分的相对标准偏差（RSD，n=7）小于10％；在实际样品中的加标回收率为70．7％-117．0％；方法的检出限（LOD，以10倍标准偏差计）为0．5～500μg／kg。方法可应用于橡胶制品中13种N-亚硝胺的测定。