超高效液相色谱-串联质谱法测定茶叶和茶汤中茚虫威对映体及7种降解产物

通过比较不同酸碱度的提取溶剂、不同SPE柱富集净化、不同上样体积以及不同溶剂清洗净化的效果，建立了茶鲜叶、绿茶、红茶、绿茶汤和红茶汤中茚虫威对映体及其降解产物的残留分析方法。采用乙腈-水溶液提取茶鲜叶、红茶、绿茶，盐析后，经C18与GCB分散固相萃取净化，浓缩近干，以甲醇-水溶液（9∶1，V/V）定容；采用PRP SPE柱富集净化茶汤，甲醇-水溶液（4∶6，V/V）清洗后，甲醇洗脱接收，浓缩近干，以甲醇-水溶液（9∶1，V/V）定容；采用Lux^® 3 μm Cellulose-2柱对茚虫威对映体及其7种降解产物进行分离，超高效液相色谱-三重四极杆串联质谱（UPLC-MS/MS）基质外标法定量测定。茚虫威对映体及其降解产物在0.005~5 mg/L浓度范围内的不同基质标准曲线相关系数r均在0.999 1以上；在低、中、高3个浓度添加水平下，平均回收率在76.9%~108.4%之间，相对标准偏差（RSD）小于16.4%；在茶鲜叶、红茶、绿茶中检出限（LOD）为0.001 mg/kg，红茶汤、绿茶汤中LOD为0.2 μg/L；在鲜叶、红茶和绿茶中定量限（LOQ）不大于0.01 mg/kg，茶汤中LOQ不大于1 μg/L。结果表明，该方法的标准曲线、相关系数、回收率和精密度均能满足残留分析要求，可用于茚虫威对映体及其降解产物的残留筛查检测。

Analysis of Indoxacarb Enantiomers and its Seven Metabolites in Tea and Tea Infusion by Ultra Performance Liquid Chromatography Tandem Triple Quadrupole Mass Spectrometry

A residual analysis method of indoxacarb enantiomers and its seven kinds of degradation products in fresh leaves,green tea,black tea,green tea infusion and black tea infusion was established,followed by comparing the extraction solvent with different pH,purification and enrichment capacity of different solid phase extraction column,different loading volume and different proportion of eluting solvent.Fresh tea leaves,black tea and green tea samples were extracted by acetonitrile and water,purified by C18 and GCB dispersive solid phase extraction.After concentrated nearly to dry,methanol-water(9∶1,V/V)was used to resolve the sample.PRP SPE column was used for the enrichment and purification of green tea infusion and black tea infusion,then methanol-water(4∶6,V/V)was used to cleanup pigments and other impurities.Finally,the analytes were eluted by methanol,and after rotary to dryness,reconstituted with methanol-water(9∶1,V/V).The indoxacarb enantiomers and its degradation products were separated by Lux 3μm Cellulose-2 column and quantified by UPLC-MS/MS using matrix external standard method.In the concentration ranged of 0.005-5 mg/L,the correlation coefficients of different matrix standard curves were above 0.9991.The average recoveries of indoxacarb enantiomers and degradation products at three spiked concentration levels ranged from 76.9%to 108.4%with the relative standard deviation(RSD)less than 16.4%.The limits of detection(LODs)in fresh leaves,black tea and green tea were 0.001 mg/kg,and that in black tea infusion and green tea infusion were 0.2μg/L.The limits of quantification(LOQs)in fresh leaves,black tea and green tea were not higher than 0.01 mg/kg,and that in black tea infusion and green tea infusion were not more than 1μg/L.The results show that the standard curves,correlation coefficients,recoveries and precisions of this method can meet the requirements of pesticide residue analysis,and it can be used for the determination and screening of indoxacarb enantiomers and degradation products in tea and other samples.