超高效液相色谱串联质谱法测定茶叶、茶汤和土壤中氟环唑、茚虫威和苯醚甲环唑残留

建立了绿茶、红茶、普洱茶、茶鲜叶、红茶汤和土壤中氟环唑、茚虫威、苯醚甲环唑残留分析方法。采用Florisil与GCB混合柱净化茶叶和土壤,BondElut C18固相萃取柱富集净化茶汤,超高效液相色谱串联质谱法测定,并对3种农药的质谱裂解和基质效应进行了研究探讨。在0.005～4.0 mg/L浓度范围内均满足线性关系,r>0.9997,仪器检出限LOD<0.002 mg/L;在高、中、低3个添加浓度水平下,不同基质样品(绿茶、红茶、普洱茶、红茶汤、茶鲜叶和土壤)中平均回收率为66.3%～111.5%;相对标准偏差为0.85%～17.6%(n=6);方法定量限LOQ分别为0.005 mg/kg(成茶)、0.002 mg/kg(茶鲜叶、土壤)和0.10!g/L(茶汤)。采用此方法检测40份红茶、绿茶出口样品,1份检出茚虫威残留量为0.014 mg/kg;4份检出苯醚甲环唑残留量为0.012～0.040mg/kg,均未检出氟环唑残留。采用此方法进行茚虫威在茶鲜叶-绿茶加工过程中的消解率、茶叶-茶汤冲泡过程中的浸出率研究,表明茚虫威在绿茶加工过程中的平均消解率为24.8%,3次冲泡的总浸出率平均值为5.2%。     

苯醚甲环唑在香蕉和土壤中的残留分析方法研究

建立了苯醚甲环唑在香蕉和土壤中的残留分析方法。样品经乙腈或丙酮、乙酸乙酯提取,中性氧化铝柱净化,GC-ECD检测。方法在0.004~0.4μg/mL范围内有良好的线性关系,香蕉和土壤中苯醚甲环唑最低检测质量分数为0.004 mg/kg。样本中添加量为0.004~1.0 mg/kg时(n=5),平均回收率为81.4%~106.3%,相对标准偏差为1.5%~11%;方法的准确度和精密度均满足农药残留分析的要求。     

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。     

80%成标干悬浮剂在黄瓜中残留动态研究

利用高效液相色谱法研究了80%成标干悬浮剂在黄瓜中的消解动态和最终残留。结果表明,80%成标干悬浮剂在黄瓜中的半衰期为7.9d。按5760g/hm2施药,共施药4次,最后一次施药5d后取样检测,残留量为0.24mg/kg。远远低于其它国家规定的最大残留量限值。     

高效液相色谱-串联质谱法测定黄瓜与土壤中烯酰吗啉和氰霜唑及其代谢物的残留量

为评价烯酰吗啉和氰霜唑在黄瓜和土壤中的安全性,建立了同时检测烯酰吗啉和氰霜唑及其代谢物4-氯-5-(4-甲苯基)-1H-咪唑-2-腈(CCIM)的高效液相色谱-串联质谱法。样品经乙腈提取,乙二胺-N-丙基硅烷键合相(PSA)和十八烷基硅烷键合相(C18)净化后,质谱多反应监测模式扫描,基质匹配标准曲线外标法定量。烯酰吗啉、氰霜唑和CCIM在0. 01～0. 5 mg/L范围内均具有良好的线性关系,相关系数(r)均大于0. 994 0,在0. 05、0. 1、0. 5 mg/kg加标浓度下,3种待测物在黄瓜和土壤中的平均回收率为78%～105%,相对标准偏差(RSD)为1. 3%～14. 8%,定量下限为0. 05 mg/kg。对35%氰霜唑·烯酰吗啉悬浮剂在黄瓜和土壤中的残留动态及最终残留量进行分析,发现烯酰吗啉、氰霜唑及CCIM之和在黄瓜和土壤中消解较快,烯酰吗啉在黄瓜和土壤中的半衰期分别为1. 2～2. 1、3. 0～9. 6 d;氰霜唑及CCIM之和在黄瓜和土壤中的半衰期为0. 9～2. 3、1. 8～6. 2 d。该方法简单、快速、灵敏度及准确度高,能够满足黄瓜和土壤中烯酰吗啉、氰霜唑及CCIM残留量的检测要求。     

敌百虫在棉花和土壤中的残留研究

建立了敌百虫在棉花和土壤中残留量的高效液相色谱-电喷雾质谱(HPLC-ESI/MS)测定方法.该方法最小检出量为1.5×10-11 g,最小检出浓度在植株和土壤中均为0.05 mg/kg,加样回收率为植株71%～76%、土壤96%～103%、棉籽74%～79%,相对标准偏差分别为3.2%～16%、5.2%～12%、4.8%～6.5%.本法快速、灵敏、准确,可以用于敌百虫的残留分析.降解动态和最终残留研究结果表明,敌百虫在植株和土壤中的半衰期(T50)分别为0.4～0.6 d和0.5～1.2 d;以推荐剂量施药2～3次,或以2倍推荐剂量施药2～3次,采收间隔21 d,棉籽和土壤中敌百虫残留量均低于0.05 mg/kg.     

高效液相色谱–串联质谱法同时测定土壤中8种杀菌剂残留

建立高效液相色谱-串联质谱法同时测定土壤中戊唑醇、腈菌唑、腈苯唑、氟硅唑、三唑酮、丙环唑、烯唑醇、苯醚甲环唑8种杀菌剂残留量的方法。采用QuEChERS样品前处理方法对土壤样品进行提取、净化和富集,用电喷雾离子源、正负离子扫描,以多反应监测(MRM)模式进行定性和定量分析。在优化的实验条件下,8种杀菌剂的质量浓度在0.01~0.50 mg/L范围内与色谱峰面积均成良好的线性关系,相关系数均大于0.995,方法检出限为0.005~0.010 mg/kg。样品平均加标回收率为85.6%~102.2%,测定结果的相对标准偏差为4.6%~13.2%(n=5)。该方法操作简便,灵敏度和准确度高,满足土壤中戊唑醇等8种杀菌剂残留量的测定要求。     

液相色谱-质谱/质谱法检测人参和土壤中多菌灵的残留动态

建立了液相色谱-质谱/质谱法测定50%多菌灵可湿性粉剂在人参和土壤中的消解动态和残留量。多菌灵在0.01~0.5μg/mL质量浓度范围内呈良好线性,相关系数为0.9985,在0.01~0.2 mg/kg加标水平下,多菌灵在人参和土壤中的回收率为82.74%~91.88%,相对标准偏差(RSD)为2.85%~6.28%,最低检出浓度为0.005mg/kg。两年两地残留实验结果表明,拌土施药剂量52 500g a.i./hm2下,人参和土壤中多菌灵半衰期分别为11.6~13.7d和10.4~13.0d,最终残留量分别在0.0075~0.0332mg/kg和0.0068~0.0428mg/kg之间。建议我国对人参中多菌灵的最大残留限量(MRL)值为0.5mg/kg,最高施药剂量52 500g a.i./hm2,安全施药间隔期28d。     

超声辅助-分散液液微萃取-气相色谱/质谱法测定葡萄酒中三唑类农药残留

以超声辅助-分散液液微萃取(UA-DLLME)为富集和净化手段,采用气相色谱/质谱法(GC/MS)检测葡萄酒中三唑类农药残留量。实验考察了萃取剂种类及用量、超声时间和盐效应等因素对萃取效率的影响。研究结果表明,最适宜的萃取条件为:以30μL十一醇为萃取剂、超声时间为10min和NaCl浓度为30g·L~(-1)。戊菌唑、氟硅唑、烯唑醇和苯醚甲环唑的检出限分别为0.020、0.021、0.039、0.019μg·L~(-1),相对标准偏差(RSD,n=5)在2.8%~7.5%之间,添加质量浓度为0.005mg·L~(-1)与0.1mg·L~(-1)时,戊菌唑、氟硅唑、烯唑醇和苯醚甲环唑的加入回收率在87.3%~107.5%之间。该方法可用于葡萄酒中上述三唑类农药残留的检测。     

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）。     

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.     

Determination and dynamics of difenoconazole residues in Chinese cabbage and soil

An analytical method was developed using a solid phase extraction （SPE） cleanup and gas chromatography for detecting the residues of difenoconazole in Chinese cabbage and soil. The recovery and the relative standard deviation of this method in Chinese cabbage was 87.6-99.0%, 1.71-10.50%, respectively; in soil was 92.4-95.5%, 4.93-10.70%, respectively. Further degradation of difenoconazole residue in Chinese cabbage and soil was studied to evaluate residue behavior and environmental safety of difenoconazole. Degradation rate of difenoconazole in both Chinese cabbage and soil followed the first order kinetics with the half-lives of 6.6-7.8 and 54.2-55.0 days, respectively.     

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.     

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.     

芹菜、草莓基质对甲胺磷等4种有机磷农药测定的影响

研究芹菜、草莓基质对甲胺磷、乙酰甲胺磷、氧化乐果、毒死蜱4种有机磷农药检测的影响。利用样品基质溶液配制标准样品,对比草莓、芹菜样品、丙酮溶液中4种农药的保留时间、峰形、峰面积。结果发现DB–5MS色谱柱上,丙酮溶液、芹菜基质、草莓基质中甲胺磷、乙酰甲胺磷、氧化乐果色谱峰出峰时间不完全重合,保留时间最大漂移0.1 min。丙酮溶剂、芹菜基质较草莓基质中的甲胺磷、乙酰甲胺磷、氧化乐果更容易出现峰拖尾现象,且芹菜基质溶液中相同浓度的甲胺磷、乙酰甲胺磷峰面积分别约是草莓基质溶液中的75%,90%。毒死蜱的保留时间、峰形、响应面积在草莓基质、芹菜基质、丙酮溶液中基本一样。     

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。     

Dissipation,residues and risk assessment of spirotetramat and its four metabolites in citrus and soil under field conditions by LC‐MS/MS

A modified Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method for the simultaneous determination of spirotetramat and its four metabolite residues in citrus, peel, pulp and soil was developed and validated by liquid chromatography with tandem mass spectrometry (LC‐MS/MS). The samples were extracted with acetonitrile (1%, glacial acetic acid, v/v) and purified using primary secondary amine and octadecylsilane. The limit of detection was 0.01–0.13 mg/kg, whereas that of quantification was 0.02–0.40 mg/kg for spirotetramat and its metabolites. The average recoveries of spirotetramat, spirotetramat‐enol, spirotetramat‐mono‐hydroxy, spirotetramat‐enol‐glucoside and spirotetramat‐ketohydroxy in all matrices were 73.33–107.91%, 75.93–114.85%, 76.44–100.78%, 71.46–103.19% and 73.08–105.27%, respectively, with relative standard deviations < 12.32%. The dissipation dynamics of spirotetramat in citrus and soil followed first‐order kinetics, with half‐lives of 2.3–8.5 days in the three sampling locations. The terminal residues of spirotetramat in four matrices at the three locations were measured below the 1.0 mg/kg maximum residue limit set by China, and residues were found to be concentrated on the peel. The risk assessment of citrus was evaluated using risk quotients. The risk quotient values were found to be significantly <1, suggesting that the risk to human health was negligible when using the recommended doses of spirotetramat in citrus. These results could provide guidance for the safe and proper application of spirotetramat in citrus in China.     

Determination of chlorpyrifos 20% EC (Dursban 20 EC) in scented rose and its products

The method for determination of chlorpyrifos is validated and dissipation behaviour of residue in scented rose and percent transfer in different products is described. GC-electron-capture detection with a HP-1, 30 m x 0.53 mm, 3.0 microm capillary column and nitrogen at 1 ml/min was used in the study. Plant matrices studied were: leaves, flowers, soil, rose water, absolute and concrete. Detector response linearity and sensitivity, limit of detection and determination, percent recovery were determined based on area response (mm2) of the standard. Analytical field and laboratory samples (rose water by hydro-distillation of the flowers, concrete and absolute by hexane extraction and condensation) were analysed for evaluation of the method. Samples were extracted with acetone, partitioned with water, saturated sodium chloride solution and dichloromethane. The organic layer was rotary-evaporated to 2 ml for cleanup with silica-carbon column. The column was eluted with dichloromethane-toluene-acetone (10:2:2, v/v/v) and the derived solution was rotary-evaporated to 5 ml for end analysis. Matrix enhancement effect was observed for leaf and soil samples for which corrective approach was followed to compensate for overestimation of the residue. Limit of detection for chlorpyrifos standard was 0.05 mg/l with good linearity of detector response (R2 = 0.99). Percent recovery ranged from 78 to 117% in different plant matrices (fortification level 1, 4 and 8 mg/l). Dissipation behaviour showed that chlorpyrifos was below detection limit by the 12th day of application on the scented rose with half life of 3.40 days on leaves and 3.10 days on flowers at 0.1% dosage. Percent transfer studies showed that 5.71, 46.91 and 38.80% of the residue from flowers was transferred to rose water, concrete and absolute, respectively.     

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.