Simultaneous detection of sulfoxaflor and its metabolites,X11719474 and X11721061, in lettuce using a modified QuEChERS extraction method and liquid chromatography–tandem mass spectrometry

An analytical method has been developed to quantify the residual levels of sulfoxaflor and its metabolites (X11719474 and X11721061) in/on cultivated lettuce grown under greenhouse conditions. Samples were extracted and purified using a quick, easy, cheap, effective, rugged, and safe ‘QuEChERS’ method (original version) following systematic method optimization and were analyzed by liquid chromatography–tandem mass spectrometry (LC–MS/MS). Good linearity with coefficient of determination ≥0.9930 was obtained and the limits of detection (LOD) and quantification (LOQ) were in the ranges of 0.003–0.006 and 0.01–0.02 mg/kg, respectively. The recovery rates of both the parent compound and its metabolites (fortified at 10 and 50× the LOQ) estimated from six replicates ranged between 81.9 and 115.5% with a relative standard deviation <12%. The validated method was applied to field‐incurred samples (collected over 7 days) sprayed once or twice with a water‐dispersible granule formulation. Notably, a substantial reduction in rate was observed after 3 days and the half‐life was short, only 1.5 days. The developed method is simple and versatile and can be used for various leafy vegetables.     

Residual level of dimethachlon in rice‐paddy field system and cooked rice determined by gas chromatography with electron capture detector

In this study, a modified quick, easy, cheap, effective, rugged and safe method coupled with gas chromatography with electron capture detection was established to determine dimethachlon residues in paddy soil, rice husk, rice straw, brown rice and cooked rice. The limits of quantification of dimethachlon were 0.01 mg/kg for paddy soil, brown rice and cooked rice and 0.02 mg/kg for rice straw and rice husk. The mean recoveries were in the range 78.59–104.7% with relative standard deviation values of <10% for dimethachlon in the five matrices. For field experiments, the final residues of dimethachlon in paddy soil were < 0.05 mg/kg and were < 1.21 mg/kg in rice straw from six sites. The final residues of dimethachlon in the brown rice at 21, 28 and 35 days after spraying from six sites were 0.08–7.58 mg/kg, and 0.16–30.1 mg/kg in rice husk. Our six test sites covered the main rice–producing areas of China. The routine rice cooking process of a Chinese family could apparently increase the removal of dimethachlon in rice compared with brown rice, and the reduction ratios were > 96%.     

Determination of RH‐5849 and indoxacarb in rice straw,rice husk,brown rice and soil using liquid chromatography–tandem triple quadrupole mass spectrometry following extraction with QuEChERS method

A fast and simple analytical method was developed for the simultaneous determination of RH‐5849 and indoxacarb in soil, rice straw, rice husk and brown rice. QuEChERS (quick, easy, cheap, effective, rugged and safe) method was used for extraction, and liquid chromatography with tandem triple quadrupole mass spectrometry was used for quantification. The matrix‐matched calibration plots were linear in the range between 25 and 5000 μg/L for soil, rice straw, rice husk and brown rice samples. All determination coefficients (R²) were ≥0.9962. The limits of detection and quantification were 1.5 and 5 μg/kg, respectively. Recoveries at three fortification levels ranged between 79.5 and 97.9% with relative standard deviations <11%. The developed method was validated and applied for the analysis of dissipation study samples. For field experiments, the half‐lives of RH‐5849 and indoxacarb in rice straw were 11.93 and 5.83 days, respectively. The method was demonstrated to be reliable for the routine monitoring of RH‐5849 and indoxacarb in rice samples. Copyright © 2016 John Wiley & Sons, Ltd.     

GC/MS法测定大米中精噁唑禾草灵和氰氟草酯残留量

采用乙腈提取,NH2固相萃取柱净化,GC/MS测定,建立了大米中精噁唑禾草灵和氰氟草酯残留量的测定方法。添加精噁唑禾草灵质量分数为0.02,0.2,0.5mg/kg,平均回收率分别为82.3%,88.8%和90.7%,相对标准偏差分别为6.8%,8.2%和3.7%,检出限为0.02 mg/kg;添加氰氟草酯质量分数为0.02,0.2,0.5mg/kg,平均回收率分别为87.7%,94.2%和92.3%,相对标准偏差分别为8.6%,5.6%和7.3%,检出限为0.02mg/kg。     

Residues and dissipation of guadipyr in rice ecological system

A modified QuEChERs method with liquid chromatography-tandem mass spectrometry for analysis of guadipyr residue and dissipation in rice matrices, paddy soil and paddy water was developed and validated. Mean recoveries and relative standard deviations in paddy soil, paddy water, rice plant, rice straw, rice hull and husked rice matrices at three spiking levels were 83.1–116.5% and 1.6–9.5%, respectively. The half-life of guadipyr was determined in 2 years at three different field sites in China via a dissipation experiment. The half-lives of guadipyr in paddy water were 0.22–0.37 days, 0.24–3.33 days in paddy soil and 0.44–1.90 days in rice plant. The terminal residues of guadipyr ranged from ND (concentrations of guadipyr were below limit of detection) to 50 μg kg^?1 in paddy soil, 10–470 μg kg^?1 in rice hull, ND70 μg kg^?1 in husked rice and ND to 110 μg kg^?1 in rice straw. The results would be helpful in fixing maximum residue limit of guadipyr, a new insecticide, in rice.     

超高效液相色谱-串联质谱法测定水稻基质中阿维菌素残留量

建立了超高效液相色谱-串联质谱法(UPLC-MS/MS)测定水稻基质中阿维菌素残留量,考察了基质效应,并对实际样品进行了检测.稻田土、稻壳、糙米和稻杆经乙腈振荡提取,稻田水经乙酸乙酯液液分配提取后,用C18固相萃取小柱或弗罗里硅土柱净化,采用UPLC-MS/MS正离子扫描测定残留的阿维菌素.稻田土、稻田水和糙米的3种添加浓度(1.0,10.0和100 μg/kg或μg/L)的平均回收率为84％～107％,相对标准偏差为4.7％～13.6％.稻壳和稻杆的2档添加浓度(10.0和100 μg/kg)的平均回收率为90％和103％,相对标准偏差为8.4％～12.9％.本方法在稻田水、糙米和稻田土中的检出限为0.3μg/kg在稻壳和稻杆中检出限为3.0 μg/kg,低于欧盟和日本在稻米中制定的阿维菌素最大残留限量值.阿维菌素在2.0～100 μg/L范围内线性关系良好( r＞ 0.999).     

QuEChERS-高效液相色谱法测定稻田土壤、糙米和秸秆中的灭草松残留

建立了一种稻田土壤、糙米和秸秆中灭草松残留量的QuEChERS-HPLC检测方法。以乙腈为提取溶剂,N-丙基-乙二胺(PSA)为吸附剂,实现样品快速制备;在C18色谱柱上,以甲醇-0.2‰H3PO4(55/45,V/V)为流动相,紫外检测器于215nm波长处检测,在0.1～5.0 mg/L范围内浓度与峰面积呈良好的线性关系,相关系数为0.9991。在添加浓度为0.05～1.0 mg/kg范围内的平均回收率为88.6%～96.8%,相对标准偏差为1.1%～2.7%,检出限为5.5×10-11g。方法能够满足水稻田土壤、糙米和秸秆样品中灭草松的残留检测。     

Simultaneous determination of trifloxystrobin and trifloxystrobin acid residue in rice and soil by a modified quick,easy, cheap,effective, rugged,and safe method using ultra high performance liquid chromatography with tandem mass spectrometry

A sensitive analytical method for the simultaneous determination of trifloxystrobin and its metabolite trifloxystrobin acid in rice including straw, bran, brown rice and soil was developed by using ultra high performance liquid chromatography coupled with tandem mass spectrometry. The fungicide trifloxystrobin and its metabolite trifloxystrobin acid were extracted using acetonitrile with 1% formic acid v/v and subsequently cleaned up by primary secondary amine, octadecylsilane or graphitized carbon black prior to ultra high performance liquid chromatography coupled with tandem mass spectrometry. The determination of two target compounds was achieved in less than 3 min using an electrospray ionization source in positive mode. The limits of detection were below 0.22 μg/kg and the limits of quantification did not exceed 0.74 μg/kg in all matrices, which were much lower than the maximum residue levels established by the Codex Alimentarius Commission. The overall average recoveries in four matrix at three levels (0.1, 1.0 and 5.0 mg/kg) ranged from 74.2 to 107.4% with a relative standard deviations of less than 7.8% (n = 5) for both analytes. The method was demonstrated to be convenient and reliable for the routine monitoring of trifloxystrobin and its metabolite. The developed method was validated and applied for the analysis of degradation study samples.     

Development and validation of a method for the analysis of cafenstrole and its metabolite in brown rice grains and rice straw using high-performance liquid chromatography

The present work reports the extraction and clean-up procedures, as well as the chromatographic conditions developed, for the determination of cafenstrole and its metabolite (CHM-03) residues in brown rice grains and rice straw using HPLC-UV detection. The method makes use of an Apollo C(18) column and acetonitrile : water : acetic acid as a mobile phase for both cafenstrole and its metabolite in rice and rice straw. Using these conditions cafenstrole and its metabolite were resolved with a retention time (R(t)) of less than 14 min. The analytes were confirmed using positive atmospheric pressure ionization LC-MS with selected ion monitoring. The average recoveries of cafenstrole were found to be 87.0-92.5 and 87.6-88.3%. However, they ranged from 81.5 to 81.6% and from 76.1 to 78.5% for cafenstrole metabolite (CHM-03), in rice grains and rice straw, respectively, with relative standard deviations ranging from 1.4 to 6.6%. The limits of detection (LODs) of both cafenstrole and its metabolite were 0.002 and 0.02 ppm and 0.025 and 0.04 ppm, respectively. Field trials with recommended or double the recommended dose revealed that the herbicide could safely be recommended for application in rice and rice straw as no residues were detected in the harvest samples.     

Fate of hexaconazole and isoprothiolane in rice,soil and water under field conditions

Residue dissipation of hexaconazole and isoprothiolane in the rice field ecosystem was determined by gas chromatography coupled with electron capture detector. Hexaconazole and isoprothiolane (33% microemulsion) were applied at two dosages, 396 g a.i. ha^–1 (the recommended dosage) and 594 g a.i. ha^–1 (1.5 times the recommended dosage) in the experimental fields in Guizhou, Hunan and Heilongjiang provinces, China, during 2011–2012. The limits of detection and limits of quantification in brown rice were 0.006 and 0.02 mg kg^–1 for hexaconazole, 0.0072 and 0.024 mg kg^–1 for isoprothiolane, respectively, and they were much below the maximum residue limits (MRLs, 0.1 mg kg^–1 for hexaconazole and 1.0 mg kg^–1 for isoprothiolane) set by China. Average recoveries of hexaconazole in water, soil, rice plants and brown rice ranged from 77.3% to 93.8% and for isoprothiolane ranged from 78.1% to 99.9% with relative standard deviations < 10%. The results showed that during harvest, the terminal residue levels of hexaconazole and isoprothiolane in brown rice samples were well below the MRLs of China following the interval of 7 days after last application. Therefore, a dosage of 396 g a.i. ha^–1 was recommended, which could be considered as safe to human beings.     

Dissipation dynamics of fenoxaprop-p-ethyl and fenoxaprop acid under Indian rice field conditions

Dissipation dynamics of fenoxaprop-p-ethyl (FPPE) and fenoxaprop acid (FPA) (metabolite) in rice field conditions was investigated for two consecutive seasons. FPPE dissipated rapidly in soil with average half life of 1.42–2.19 days. Dissipation followed first-order kinetics. The method was validated in terms of accuracy, linearity, specificity and precision. Linearity was in the range of 0.005–5 µg mL^?1 with limit of detection as 0.002 and 0.001 µg mL^?1 for fenoxaprop-p-ethyl and fenoxaprop acid, respectively. Quantitation limit in soil, grain, straw and husk were 0.005, 0.008, 0.01 and 0.01 µg g^?1 for fenoxaprop-p-ethyl, and 0.005, 0.01, 0.01 and 0.01 µg g^?1 for fenoxaprop acid, respectively. Recovery in soil, rice grains, straw and husk ranged from 81.60–93.40, 77.85–87.00, 75.20–84.40 and 76.00–87.20% for FPPE and 82.50–88.20, 76.25–83.00, 74.80–83.60 and 75.00–85.40% for FPA, respectively. Below detectable limit of residues of FPPE and metabolite were observed in soil, rice grain, husk and straw samples at harvest. FPPE and FPA were of short persistence under field conditions and residues were below European Union-Maximum Residue Limits in all matrices that would cause adverse effect on environment and human/animal health.     

QuEChERS-液相色谱-质谱法快速筛查和确证大米中205种农药残留

结合QuEChERS法与液相色谱-三重四极杆复合线性离子阱质谱(LC-Q-TRAP/MS)技术,建立了大米中205种农药残留的快速筛查确证方法。大米样品经乙腈提取,N-丙基乙二胺(PSA)、无水MgSO₄和C₁₈吸附剂净化后,采用多反应监测-信息关联采集-增强子离子(MRM-IDA-EPI)扫描方式及谱库检索技术,通过对化合物的保留时间、离子对以及高灵敏度的EPI谱库检索比对,完成了205种农药的筛查与确证,并采用外标法定量,实现了大米样品中205种农药的定性和定量分析。结果表明,所有农药的线性相关系数均大于0.995;方法的定量限在0.5~10.0 μg/kg之间。在10、50 μg/kg两个添加水平下,205种农药的平均回收率在62.4%~127.1%之间;相对标准偏差(RSD)在1.0%~20.0%之间。该方法能够对大米样品进行实际检测,且检测时间不超过20 min。该方法快速、准确、灵敏度高,适合于大米中农药残留的快速、全面筛查和确证分析。     

亲水作用色谱-串联质谱法测定稻米中的草甘膦和氨甲基磷酸残留量

采用亲水作用色谱-串联质谱建立了同时测定稻米中草甘膦及其主要代谢物氨甲基磷酸残留量的检测方法。样品经水提取,C18固相萃取柱和超滤膜净化,以1 mmol/L乙酸铵溶液(用氨水调pH=11.0)-乙腈为流动相,亲水作用色谱柱分离,采用电喷雾离子源、负离子扫描模式和多反应监测模式质谱检测,基质匹配标准溶液外标法定量。草甘膦和氨甲基磷酸分别在0.001～0.250 mg/L和0.0025～0.250 mg/L质量浓度范围内线性关系良好,检出限(信噪比为3)分别为0.010 mg/kg和0.020 mg/kg。通过对空白大米样品进行0.100、0.500和2.500 mg/kg 3个加标水平的回收试验,草甘膦和氨甲基磷酸的平均回收率和相对标准偏差分别为96.3%～107.3%和1.3%～9.1%(n=3)。该方法无需衍生,净化步骤简便快速,定量准确,可满足稻米中草甘膦和氨甲基磷酸残留检测要求。     

Validation of QuEChERS-based UPLC-MS/MS method for determination of quinoid niclosamide (LDS) residue in water,soil and rice samples

A sensitive, rapid and easy analytical method was validated for the determination of quinoid niclosamide (LDS) molluscicide in water, rice and soil using a QuEChERS extraction procedure and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) detection. The LDS was extracted by using acetonitrile and then cleaned up by using dispersive solid-phase extraction with florisil and C18 sorbents. The determination of the target compound was achieved in less than 3 min using an electrospray ionisation source in negative mode. The overall average recoveries for this method in water, rice and soil matrix at three fortified levels ranged from 82.54 to 99.9%, with relative standard deviations in the range of 1.51 to 4.86% (n = 5). The calculated limits of detection were lower than 0.1 µg kg^?1 and quantification was 5 µg kg^?1; these values were much lower than the maximum residue levels established by the Australian standard (0.01 mg kg^?1). The results of the method validation confirmed that this proposed method is convenient and reliable for the determination of LDS molluscicide in water, rice and soil samples.     

高效液相色谱-串联质谱法测定稻米和稻壳中井冈霉素A的残留

本文建立了稻米和稻壳中井冈霉素A的高效液相色谱-串联质谱(HPLC-MS/MS)分析方法。样品用甲醇-水(9+1)涡旋提取,过滤膜后进行HPLC-MS/MS分析。用多反应监测技术确定井冈霉素A的两对离子对m/z498.2/178.1、m/z498.2/336.1为定性离子对,m/z498.2/178.1为定量离子对。方法的线性范围为0.005～0.2mg/L,其中稻壳的线性相关系数为0.9993,稻米的线性相关系数为0.9988。稻米、稻壳的0.05、0.1、0.5 mg/kg三个浓度的添加回收率为71.6%～88.8%,相对标准偏差(RSD)为1.89%～8.16%。方法的定量限(LOQ)为5μg/kg。     

气相色谱-三重四极杆质谱法快速检测鸡蛋中氟虫腈及其代谢物

建立了QuEChERS前处理技术结合气相色谱-三重四极杆质谱（GC-MS/MS）分析鸡蛋中氟虫腈及其代谢物的快速检测方法。样品由乙腈提取,然后经150 mg MgSO₄脱水和50 mg N-丙基乙二胺（PSA）、50 mg C18净化,采用农药残留专用柱（TR-Pesticide Ⅱ）进行气相色谱分离,以定时反应监测（timed-SRM）模式进行检测,基质曲线外标法定量。结果表明,氟虫腈及其代谢物在1.0~200 μg/L范围内呈良好线性,线性相关系数（R²）均大于0.999,定量限为0.5~1.0 μg/kg;氟虫腈及其代谢物在3个添加水平（2、5和10 μg/kg）下的加标回收率为87.8%~111.5%,相对标准偏差（RSD,n=3）为2.0%~9.2%,该方法能满足欧盟规定的鸡蛋中氟虫腈及其代谢物的残留检测限量要求。     

超高效液相色谱-线性离子阱/静电场轨道阱高分辨质谱快速测定大米中15种营养成分

建立了超高效液相色谱-线性离子阱/静电场轨道阱高分辨质谱(UHPLC-LTQ/Orbitrap HRMS)同时快速检测大米中15种营养成分(8种维生素E、6种γ-谷维素及β-胡萝卜素)的方法。样品经过含0.05%(v/v)2,6-二叔丁基-4-甲基苯酚(BHT)的甲醇溶液超声提取处理后,用Poroshell 120 PFP色谱柱(150 mm×3.0 mm,2.7μm)分离,以0.1%(v/v)甲酸水溶液和含0.1%(v/v)甲酸的甲醇溶液为流动相,在正离子模式下通过UHPLC-LTQ/Orbitrap HRMS进行全扫描分析。15种营养成分可在13 min内获得满意的分离效果。15种营养成分在各自的线性范围内线性关系良好,相关系数(r)≥0.995 0,15种营养成分的检出限(S/N=3)为0.2~1.8μg/L,定量限(S/N=10)为0.7~6.1μg/L,在3个添加水平下的平均加标回收率分别为73.2%~101.5%,相对标准偏差(RSD)为1.1%~5.0%(n=3)。该法准确,高效,可靠,适用于大米中多种营养成分的同时测定。     

QuEChERS-在线凝胶色谱-气相色谱-质谱法测定大米、黍子和小麦中34种农药残留

采用QuEChERS方法结合在线凝胶色谱-气相色谱-质谱（GPC-GC-MS）系统,建立了大米、黍子和小麦中34种中高毒农药的快速筛查方法。研究了称样量、萃取剂、净化吸附剂种类对大米样品提取净化效果的影响并考察了基质效应和分析保护剂的使用效果,采用选择离子监测（SIM）模式,外标法定量。结果表明,34种农药在大米、黍子和小麦中的检出限分别为0.0281~5.30、0.0282~4.82、0.0273~5.13 μg/kg;在0.05 μg/g添加水平的平均回收率分别为94.5%~117.1%、83.1%~121.7%、93.1%~120.2%;相对标准偏差（RSD,n=6）分别为2.6%~14.5%、3.4%~15.1%、3.5%~15.2%。该方法消耗试剂少,分析成本低,符合绿色化学的理念,具有操作便捷、快速、通用性强等特点,适用于大米、黍子和小麦中34种农药残留的快速筛查与检测。     

Rapid multiplug filtration cleanup method for the determination of 124 pesticide residues in rice,wheat, and corn

A simple and rapid multiplug filtration cleanup method based on multiwalled carbon nanotubes was developed to determine 124 pesticide residues in rice, wheat, and corn, which could be done in a few seconds without conditioning and elution steps. Various combinations of sorbents were optimized for each matrix with a dispersive solid‐phase extraction procedure to get a satisfactory recovery and clean‐up performance. Good linearity was obtained for all pesticides with calibration curve coefficients larger than 0.9958. Most recoveries for the majority pesticides were between 70 and 120% (n = 5) with relative standard deviations below 20%. The limit of detection was 0.1–1.3 μg/kg, and the limit of quantification was 0.2–4.3 μg/kg for the pesticides in all matrices. The work suggests that the multiplug filtration cleanup method is better than the dispersive solid‐phase extraction method and it could be applied to routinely monitor pesticide residues in market samples.     

Determination,residue and risk assessment of trifloxystrobin,trifloxystrobin acid and tebuconazole in Chinese rice consumption

A simple and rapid analytical method for the detection of trifloxystrobin, trifloxystrobin acid and tebuconazole in soil, brown rice, paddy plants and rice hulls was established and validated by liquid chromatography with tandem mass spectrometry. Acceptable linearity (R² > 0.99), accuracy (average recoveries of 74.3–108.5%) and precision (intra- and inter-day relative standard deviations of 0.9–8.8%) were obtained using the developed determination approach. In the field trial, the half-lives of trifloxystrobin and tebuconazole in paddy plants were 5.7–8.3 days in three locations throughout China, and the terminal residue concentrations of trifloxystrobin and tebuconazole were <100 and 500 μg/kg (maximum residue limits set by China), respectively, at harvest, which indicated that, based on the recommended application procedure, trifloxystrobin and tebuconazole are safe for use on rice. The risk assessment results demonstrated that, owing to risk quotient values of both fungicides being <100%, the potential risk of trifloxystrobin and tebuconazole on rice was acceptable for Chinese consumers. These data could provide supporting information for the proper use and safety evaluation of trifloxystrobin and tebuconazole in rice.