材料期刊网

建立了茶叶中农药氯噻啉残留的液相色谱-串联质谱检测方法。茶叶样品用乙腈提取，提取液经 QuEChERS法净化，利用 PSA（ N-丙基乙二胺）、C18、GCB（石墨化炭黑）等吸附剂材料进一步去除杂质，净化液经过离心后取上清液以水等体积稀释。以乙腈-0.1％（v／v）甲酸水溶液为流动相，在0.30 mL／min 流速下梯度洗脱，用 C18色谱柱进行液相色谱分离，电喷雾正离子模式电离（ESI＋），选择反应监测（SRM）模式检测，外标法定量。结果表明：氯噻啉在1~500μg／L范围内线性关系良好（相关系数 r为0.9999），定量限为0.01 mg／kg（ S／N≥10），在乌龙茶和绿茶中3个添加水平（0.01、0.3和3 mg／kg）的平均回收率为87.0％~101.0％，相对标准偏差（RSD，n=7）在2.1％~13.1％之间。对多种茶叶的测定结果表明，该方法操作简便、成本低、准确性高、特异性好、分析速度快，可以对茶叶中氯噻啉残留进行定性和定量检测。

The method for the determination of imidaclothiz residue in tea by liquid chromatog-raphy-tandem mass spectrometry( LC-MS/MS ) has been developed. The imidaclothiz in tea was extracted by acetonitrile and purified by QuEChERS with PSA( primary secondary amine), C18,GCB(graphitized carbon black)as the adsorbents. The purified solution was centrifuged and the supernatant was diluted with water of equal volume. The separation was performed on a C18 column with a gradient elution program of acetonitrile( containing 0. 1%( v/v)formic acid) and water at a flow rate of 0. 30 mL/min. The mass spectrometer was carried out with electros-pray ion source in the positive mode( ESI+)and selective reaction monitoring( SRM),quanti-fied by external standard solution. The results showed that the mass concentration of imidaclo-thiz in the range of 1 to 500 μg/L was linearly correlated with the peak area,and the correlation coefficient( r)was 0. 999 9. The limit of quantification( LOQ,S/N≥10)was 0. 01 mg/kg. The recoveries in oolong tea and green tea at three spiked levels(0. 01,0. 3 and 3 mg/kg)varied from 87. 0%-101. 0% and the relative standard deviations( RSDs,n=7)were between 2. 1%and 13. 1%. The real sample tests showed that the method is simple,cheap,accurate,specific, rapid,and suitable for the qualitative and quantitative confirmation of imidaclothiz residue in tea.