Simultaneous determination of difenoconazole,trifloxystrobin and its metabolite trifloxystrobin acid residues in watermelon under field conditions by GC–MS/MS

An optimized quick, easy, cheap, effective, rugged and safe method for the simultaneous determination of difenoconazole, trifloxystrobin and its metabolite trifloxystrobin acid residues in watermelon and soil was developed and validated by gas chromatography with tandem mass spectrometry. The samples were extracted with acetonitrile (1% formic acid) and cleaned up by dispersive solid‐phase extraction with octadecylsilane sorbent. The limit of quantification of the method was 0.01 mg/kg, and the limit of detection was 0.003 mg/kg for all three analytes. The recoveries of the fungicides in watermelon, pulp and soil were 72.32–99.20% for difenoconazole, 74.68–87.72% for trifloxystrobin and 78.59–92.66% for trifloxystrobin acid with relative standard deviations of 1.34–14.04%. The dissipation dynamics of difenoconazole and trifloxystrobin in watermelon and soil followed the first‐order kinetics with half‐lives of 3.2–8.8 days in both locations. The final residue levels of difenoconazole and trifloxystrobin were below 0.1 mg/kg (maximum residue level [MRL] set by China) and 0.2 mg/kg (MRL set by European Union), respectively, in pulp samples collected 14 days after the last application. These results could help Chinese authorities to establish MRL of trifloxystrobin in watermelon and provide guidance for the safe and proper application of both fungicides on watermelon.     

苯醚甲环唑在芹菜及其土壤中的残留测定和消解动态研究

采用气相色谱-电子捕获检测, 对芹菜及其土壤中的苯醚甲环唑消解动态和最终残留量进行了研究, 评价了苯醚甲环唑在芹菜上使用后的残留行为和环境安全性. 苯醚甲环唑在芹菜及土壤中的残留消解动态均符合一级动力学方程, 苯醚甲环唑在芹菜上消解快; 苯醚甲环唑最终残留量与施药的剂量、施药次数及采样的间隔时间有关; 水解研究表明, 苯醚甲环唑是稳定的农药, 在不同温度和不同pH的研究条件下水解半衰期均大于166 d, 碱性条件更有利于苯醚甲环唑的降解.     

Simultaneous determination and method validation of difenoconazole,propiconazole and pyraclostrobin in pepper and soil by LC–MS/MS in field trial samples from three provinces,China

A liquid chromatography–electrospray ionization tandem mass spectrometry method was developed for simple and accurate detection of the fungicides difenoconazole, propiconazole and pyraclostrobin in peppers and soil. Three fungicides residues were extracted from samples by acetonitrile and cleaned up by dispersive solid‐phase extraction before instrumental analysis. The accuracy and precision of the method were evaluated by conducting an intra‐ and inter‐day recovery experiment. The limits of quantification and detection of difenoconazole, propiconazole and pyraclostrobin in pepper and soil were 0.005 and 0.0015 mg/kg, respectively. The recoveries were investigated by spiking pepper and soil at three levels, and were found to be in the ranges 79.62–103.15% for difenoconazole, 85.94–103.35% for propiconazole and 80.14–97.69% for pyraclostrobin, with relative standard deviations <6.5%. Field experiments were conducted in three locations in China. The half‐lives of difenoconazole, propiconazole and pyraclostrobin were 5.3–11.5 days in peppers and 6.1–32.5 days in soil. At harvest, pepper samples were found to contain difenoconazole, propiconazole and pyraclostrobin well below the maximum residue limits of European Union at the interval of 21 days after last application following the recommended dosage.     

气相色谱法分析甘蓝及其土壤中的烯啶虫胺残留

建立了气相色谱测定甘蓝植株和土壤中烯啶虫胺残留量的分析方法。样品采用丙酮-水(4:1, v/v)进行提取,经弗罗里硅土柱净化,用电子捕获检测器进行测定。实验结果表明,添加水平为0.02～2.00 mg/kg时,烯啶虫胺在甘蓝植株和土壤中的平均回收率分别为88.73%～94.13%和90.82%～96.27%,相对标准偏差分别为3.09%～7.39%和2.01%～4.92%;方法的最低检出限为0.02 mg/kg。该方法快速简便、灵敏度高、重现性好,可用于环境系统中烯啶虫胺残留量的检测分析。     

Development of extraction procedures for the determination of imidacloprid: application to residue analysis and dynamics of two formulations in Chinese cabbage

This study was undertaken to investigate whether an additional column clean-up procedure can affect the accuracy of an analytical method developed for the determination of imidacloprid residues in Chinese cabbage. Thereafter, the residue levels and the degradation rates of imidacloprid were investigated in experimental Chinese cabbage plots after treatment with two different commercial formulations: emulsifiable concentrate (EC) and wettable powder (WP). The analyte was determined using high-performance liquid chromatography-ultraviolet detection (HPLC-UVD) and confirmed by high-performance liquid chromatography-mass spectrometry (HPLC-MS) in the select ion-monitoring mode. The mean recoveries ranged from 75.34 to 98.00% and 96.95 to 100.97%, with relative standard deviations of 0.86-4.14 and 1.22-3.52%, in samples treated with and without additional column clean-up procedures, respectively. The minimum detectable amount of imidacloprid was 4 ng, while the limits of detection and quantitation were 0.2 and 0.5 ppm, respectively. The degradation of pesticide was monitored throughout a period of 13 days under greenhouse conditions. Although the behaviors of the EC and WP formulations appear to be similar, the absolute residue levels obtained with EC and WP treatments differed slightly. When imidacloprid formulations were applied (as foliar treatments) according to the recommended rate, the final residues (13 days post-treatment) in Chinese cabbage were much lower than the maximum residue limit (MRL = 3.5 ppm) established by the Korean Food and Drug Administration. Taken together, our study suggests that the analysis of imidacloprid can be performed without an additional column clean-up procedure, and the decline curve and the residue levels in Chinese cabbage could change if the same active ingredient is used in different formulations.     

甘蓝及其土壤中灭幼脲的残留检测与消解动态研究

建立了杀虫剂灭幼脲在甘蓝及其土壤中残留量的高效液相色谱检测方法。样品经提取和固相萃取(SPE)小柱净化后进行测定,灭幼脲的回收率为77.1%~81.6%,变异系数在4.3%~9.7%之间。残留动态研究表明,灭幼脲在甘蓝及其土壤中消解的半衰期分别为4~6 d和15~16 d;以20 g制剂/亩的剂量(最高推荐剂量)施药14d后收获时,甘蓝中最高残留量为0.38 mg/kg,土壤中最高残留量为0.28 mg/kg。     

西红柿、卷心菜中残留丙溴磷的提取及气相色谱-火焰光度检测法分析

 报道了一种简便、快速的西红柿、卷心菜中丙溴磷的提取净化及测定方法。采用丙酮 正己烷 (体积比为 1∶1)提取西红柿、卷心菜中的丙溴磷 ,经活性炭净化后 ,用气相色谱 火焰光度检测法直接测定其含量。丙溴磷在西红柿、卷心菜中的加标回收率分别为 96 .2 %～ 10 5 .9% ,94.7%～ 10 2 .3% ,RSD分别为 3.7%～ 4.9% ,3.7%～5 .0 %。西红柿、卷心菜中丙溴磷的最低检出限为 0 .0 6mg/kg。     

Simultaneous enantioselective determination of triazole fungicide difenoconazole and its main chiral metabolite in vegetables and soil by normal-phase high-performance liquid chromatography

Herein is reported, for the first time, a simple and highly sensitive chiral high-performance liquid chromatography (HPLC) method for the simultaneous quantitative determination of difenoconazole stereoisomers and their hydroxylated metabolite difenoconazole alcohol (CGA-205375) enantiomers in vegetables and soil matrix. The separation of difenoconazole and CGA-205375 including their simultaneous enantioseparation was studied using four different polysaccharide-type chiral stationary phases (CSPs) in combination with n-hexane-polar organic alcohols mobile phase. Chiralcel OJ consisting of 25?% of cellulose tris(4-methylbenzoate) coated on wide-pore polysaccharide silica gel exhibited higher resolving ability compared to cellulose tris(3,5-dimethylphenylcarbamate) (Chiralcel OD) as well as to its similar amylose derivative (Chiralpak AD) CSPs for this particular set of chiral analytes. Baseline separation and simultaneous enantioseparation of difenoconazole and its metabolite CGA-205375 could be achieved under optimized separation conditions. Based on the established HPLC method, enantioselective analysis method for this fungicide and its main chiral metabolite in vegetables and soil matrix were developed and validated. Parameters including the matrix effect, linearity, precision, accuracy, and stability were evaluated. Under the optimal conditions, the mean recoveries from cucumber, tomato, and soil matrix ranged from 81.65 to 94.52?%, with relative standard deviations in the range of 1.05-8.32?% for all stereoisomers. Coefficients of determination R (2)?≥?0.998 were achieved for each enantiomer in the cucumber, tomato and soil matrix calibration curves within the range of 0.5-50?μg mL(-1). The limits of quantification for all enantiomers in three matrices were all below 0.1?μg mL(-1). The methodology was successfully applied for simultaneous enantioselective analysis of difenoconazole stereoisomers and their metabolite in the real samples, indicating its efficacy in investigating the environmental stereochemistry of difenoconazole in food and environmental matrix.     

应用GC-MS测定葡萄中的5种农药残留

酿酒葡萄是河北昌黎的主要水果种植品种,由于受海洋气候的影响,当地空气湿热,葡萄病害十分严重,因而农药使用十分频繁,为了评价其农药残留水平,我们采用丙酮提取,凝胶分离,硅胶小柱净化,GC-MS的选择离子方式检测对采集的葡萄样品进行5种农药(百菌清、精甲霜灵、苯醚甲环唑、嘧菌酯、高效氯氟氰菊酯)的残留分析。     

气相色谱-负化学离子源质谱法检测食品中苯醚甲环唑的残留量

建立了一种用于各种食品中苯醚甲环唑残留量的气相色谱-负化学离子源质谱(GC-MS/NCI)检测方法。用乙酸乙酯对各类样品中的苯醚甲环唑进行提取,固相萃取(SPE)净化后由GC-MS/NCI在选择离子监测模式下进行测定。方法的准确度和精密度高,多数样品在0.01,0.04,0.10 mg/kg三个添加水平下苯醚甲环唑的回收率处于70%和120%之间,相对标准偏差（RSD）不大于9.5%。方法在0.02～1.00 mg/L范围内有良好的线性关系,且灵敏度高,最低检测限达到0.0005 mg/kg;选择性好,抗干扰能力强,能消除复杂基质带来的干扰,适合各种食品中苯醚甲环唑残留量的确证分析。     

30％毒死蜱微乳剂在甘蓝及土壤中的残留动态研究

利用气相色谱（配FPD检测器）分析测定了30％毒死蜱微乳剂在甘蓝和土壤中的残留消解动态和最终残留量。毒死蜱色谱峰面积与质量浓度在0．01～0．5mg／L范围内呈良好的线性关系,相关系数,为0．9992。甘蓝和土壤中毒死蜱的最低检出浓度均为0．005mg／kg,在0．01,0．02,0．1mg／kg3个添加水平下,甘蓝及土壤中毒死蜱的平均回收率分别为80．1％～96．4％和82．1％-98．7％,变异系数分别为1．2％～5．0％和2．5％-3-3％（n=10）。残留消解动态的结果表明：毒死蜱在甘蓝中的半衰期为5．8～10．5d,在土壤中的半衰期为8．0～10．5d。毒死蜱在收获期甘蓝及土壤中最终残留量均低于我国规定的限量值（1．0mg／kg）。     

An analytical method for prohexadione in Chinese cabbage and apple

A residual determination method as a regulatory residue method was developed using HPLC‐UVD for prohexadione residues in Chinese cabbage (Brassica pekinensis) and apple (Malus domestica). The developed method consisted of solid–liquid extraction with acidic acetonitrile and ion‐suppression liquid–liquid partitioning, followed by anion exchange cartridge cleanup. The limits of detection and quantitation for the method were 0.005 and 0.02 mg/kg, respectively. The method gave good linearity in the range of 0.02–2.5 mg/kg. Accuracy and precision ranged from 84.1 to 94.1% and from 2.4 to 6.9%, respectively. Additionally, the confirmative conditions of LC‐MS/MS for prohexadione were set in negative electrospray ionization mode with transitions of m/z 211.4 → 167.5 and m/z 211.4 → 123.5 in the selected reaction monitoring mode. The applicability of the method was demonstrated by analyzing real samples collected from local markets in Seoul, Republic of Korea. This developed method fully deserves consideration in accordance with its sensitivity, accuracy and precision required for residue analysis of prohexadione in Chinese cabbages and apples. Copyright © 2010 John Wiley & Sons, Ltd.     

Persistence and dissipation of fluopicolide and propamocarb on cabbage and soil under semi-arid climatic conditions

Persistence and dissipation of fluopicolide and propamocarb were studied on cabbage and soil as per good agricultural practices over a period of 2 years. A modified QuEChERS analytical method in conjunction with gas chromatography (GC) and GC–mass spectrometry was used for analysis of fluopicolide and its metabolite, 2,6-dichlorobenzamide, and propamocarb in cabbage and soil. The results of the method validation were satisfactory with recoveries within 74.5–100.81% and relative standard deviations 4.8–13.9% (n = 6). The limit of detection (LOD) and limit of quantification (LOQ) of both fluopicolide and 2,6-dichlorobenzamide were 0.003 µg mL^?1 and 0.01 mg kg^?1, respectively. The LOD and LOQ of propamocarb were 0.03 µg mL^?1 and 0.1 mg kg^?1, respectively. During 2013, the initial residue deposits of fluopicolide on cabbage were 0.60 and 1.48 mg kg^?1 from treatments at the standard and double doses of 100 and 200 g a.i. ha^?1 which dissipated with the half-life of 3.4 and 3.7 days. During 2014, the residues were 0.49 and 1.13 mg kg^?1 which dissipated with the half-life of 4.2 and 5.1 days. Propamocarb residues on cabbage were 5.36 and 12.58 mg kg^?1 in the first study (2013) and 4.85 and 10.26 mg kg^?1 in the second study (2014) from treatments at the standard and double doses of 1000 and 2000 g a.i. ha^?1, respectively. The residues dissipated with the half-life of 4–5.5 days. The preharvest interval, the time required for fluopicolide + propamocarb residues to dissipate below the maximum residue limits (notified by EU) at the standard dose, was 11.8 and 14 days during 2013 and 2014. Residue of 2,6-dichlorobenzamide was always <LOQ in cabbage. Residues of fluopicolide, 2,6-dichlorobenzamide and propamocarb were <LOQ in field soil at harvest.     

高效液相色谱荧光检测法测定蔬菜中残留的甲氨基阿维菌素苯甲酸盐

建立了甘蓝和蘑菇中甲氨基阿维菌素苯甲酸盐的固相萃取-高效液相色谱荧光分析方法。蔬菜样品用乙酸乙酯提取,提取液旋转浓缩近干后用少量乙酸乙酯溶解,再经PRS固相萃取(SPE)柱净化,洗脱液经氮气吹干后用氮甲基咪唑和三氟乙酸酐衍生,衍生物用高效液相色谱分析,采用外标法定量。在添加浓度1.0～20.0 μg/kg范围内,平均添加回收率为78.6%～84.9%,日内相对标准偏差(RSD)为2.7%～6.0%,日间RSD为3.1%～8.9%,检出限为0.10 μg/kg。甲氨基阿维菌素苯甲酸盐衍生物在0.002～0.10 mg/L范围内呈良好的线性关系,相关系数为0.9999。     

Buprofezin dissipation and safety assessment in open field cabbage and cauliflower using GC/ITMS employing an analyte protectant

An analytical method for the determination of buprofezin residues in cabbage and cauliflower was developed and validated using gas chromatography with ion trap mass spectrometry. The analyte protectant d ‐sorbitol was used at a concentration level of 0.5 mg mL^?1 in acetonitrile instead of in matrix for constructing the calibration curves of the buprofezin standard. The average recoveries ranged from 91.3 to 96.8%, with an RSD of ≤2.7%. The limits of detection and quantitation of the method in cabbage and cauliflower were 1.3, 1.7 and 4.3, 6.2 μg kg^?1, respectively. The residual levels and dissipation kinetics of buprofezin 25% wettabe powder in cabbage and cauliflower cultivated under open field conditions was investigated at the single (T1) and double (T2) recommended rates of application. Half‐life periods were found to be 1.73 and 2.1 days in cabbage, whereas in cauliflower, these values were 1.85 and 2.36 days at T1 and T2, respectively. Based on the dissipation study, and the maximum residue limit value of 0.05 mg kg^?1, the proposed pre‐harvest interval of buprofezin in cabbage was 3–6 days and that in cauliflower was 4–10 days. The results showed that buprofezin is safe for application at both recommended application rates.     

高效液相色谱-串联质谱法测定荔枝花粉和花蜜中腈菌唑和苯醚甲环唑残留

采用改良的QuEChERS-高效液相色谱-串联质谱（HPLC-MS/MS）技术,建立了荔枝花粉和花蜜中2种主要杀菌剂腈菌唑和苯醚甲环唑的测定方法。花粉和花蜜样品均由乙腈提取,花粉样品经0.9 g无水硫酸镁、0.15 g N-丙基乙二胺（PSA）和0.15 g十八烷基键合硅胶（C₁₈）吸附剂净化,花蜜样品由0.9 g无水硫酸镁和0.15 g PSA净化。采用Poroshell-120 EC-C₁₈色谱柱分离,以0.1%（v/v）甲酸水溶液-乙腈（25∶75,v/v）为流动相等度洗脱,在电喷雾离子（ESI）源、正离子扫描和选择离子监测模式下进行检测,基质匹配标准溶液法定量。结果显示：腈菌唑和苯醚甲环唑在1~100 μg/L范围内线性关系良好,相关系数（r²）均大于0.9990;腈菌唑和苯醚甲环唑的检出限（LOD）分别为0.25 μg/kg和0.50 μg/kg,定量限（LOQ）分别为0.83 μg/kg和1.7 μg/kg;腈菌唑和苯醚甲环唑在荔枝花粉和花蜜样品中的平均加标回收率分别为87.0%~95.2%和90.1%~96.4%,相对标准偏差（RSD）分别为1.2%~3.6%和0.7%~4.1%。该法快速、简便、灵敏,可用于荔枝花粉和花蜜样品中腈菌唑和苯醚甲环唑的痕量测定,可为蜜蜂等授粉昆虫的暴露性风险评估提供技术支持。     

Simultaneous determination and dissipation behaviour of thifluzamide and difenoconazole in grapes using a QuEChERS method with ultra high-performance liquid chromatography and tandem mass spectrometry

In this study, a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was used for the simultaneous determination of thifluzamide and difenoconazole in grapes by ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC–MS/MS) using a Waters Acquity UHPLC BEH C18 column. To compare the effects of different sorbents for thifluzamide and difenoconazole in grapes, samples were extracted with acetonitrile and cleaned up using five different types of sorbents at the same concentration level (0.1 mg/kg). The method was validated at three fortification concentrations (0.05, 0.1, 0.5 mg/kg) with five replicates in each matrix using 40 mg of primary secondary amine (PSA) + 10 mg of graphitised carbon black (GCB) as clean-up sorbents. The recoveries were between 76.3 and 109.3%, and the RSDr (intra-day precision, n = 5) and RSD_R (inter-day precision, n = 15) values ranged from 3.5 to 8.1% and 5.8 to 22.2%, respectively. The limits of quantification (LOQ) for thifluzamide and difenoconazole were 0.07 and 0.04 mg/kg, respectively. The method showed excellent linearity and reliability. The results demonstrated that the method was effective in detecting the two compounds. In this study, we also investigated the dissipation behaviours of thifluzamide and difenoconazole in grapes. The dissipations of thifluzamide and difenoconazole followed the first-order kinetics with the half-lives of 3.9–16.3 days.     

施用污泥堆肥对土壤和小白菜重金属积累的影响

以金华市污水处理厂污泥为研究对象,利用它对小白菜进行的盆栽试验,研究了以污泥作堆肥对土壤和小白菜重金属积累的影响.结果表明,随着污泥堆肥施用量的增加,土壤和小白菜地上部组织的Cu、Zn、Cd和Pb含量也呈积累趋势,当施用量为10%时,地上部组织的重金属含量超过国家食品卫生标准.由此说明,在污泥堆肥和利用过程中应进一步严格控制重金属及其在作物体中积累,尤其控制可食部分中重金属的含量和污泥堆肥长期施用过程中的重金属在土壤和作物中的积累.     

Liquid chromatographic determination of iprovalicarb in cabbage and soil

A method was developed for the determination of iprovalicarb, a new carbamic acid-amino acid fungicide, by liquid chromatography with UV detection. The method uses a reversed-phase C18 column with lambdamax at 215 nm and methanol-water (72 + 25, v/v) as the mobile phase. Cabbage head and leaves fortified with iprovalicarb were extracted with acetone. Partitioning of the fungicide into dichloromethane was followed by column cleanup on neutral alumina. Fortified soil samples were extracted with acetonitrile, and the extract was subjected to column cleanup. The average recoveries of iprovalicarb from cabbage head, leaves, and soil were 86.50, 82.0, and 84.3%, respectively, for fortification levels of 1 and 2 microg/g for cabbage head and leaves and 2 and 4 microg/g for soil.     

Simultaneous determination of boscalid and fludioxonil in grape and soil under field conditions by gas chromatography/tandem triple quadrupole mass spectrometry

A gas chromatography–tandem mass spectrometry method was developed and validated to simultaneously determine boscalid and fludioxonil in grape and soil samples. These samples were extracted with 10 mL of acetonitrile and purified using a mixed primary secondary amine/octadecylsilane sorbent. The method showed good linearity (R² > 0.99) in the calibration range 0.005–2 μg/mL for both pesticides. The limits of detection and quantification for the two analytes in grape and soil were 0.006 and 0.02 mg/kg, respectively. Fungicide recoveries in grape and soil were 81.18–92.11% for boscalid and 82.73–97.67% for fludioxonil with relative standard deviations of 1.31–10.31%. The established method was successfully applied to the residual analysis of boscalid and fludioxonil in real grape and soil samples. The terminal residue concentrations of boscalid and fludioxonil in grape samples collected from Anhui and Guizhou were <5 mg/kg (the maximum residue limit set by China) 7 days after the last application and 1 mg/kg (the maximum residue limit set by USA) 14 days after the last application. These results could provide guidance for the proper and safe use of boscalid and fludioxonil in grape and help the Chinese government to establish an MRL for fludioxonil in grape.