离子交换固相萃取-高效液相色谱法研究吡虫啉在梨中的分布及残留动态

建立一种以固相萃取(SPE)、高效液相色谱(HPLC)为基础的测定梨果皮、果肉中吡虫啉残留量的方法。样品用乙腈进行提取,经二氯甲烷液液分配后用阳离子交换固相萃取(SCX-SPE)柱净化,高效液相色谱/二极管阵列检测法(HPLC/DAD)测定。各种添加水平(果皮:0.05、0.1、0.5、2 mg/kg;果肉:0.05、0.5、1mg/kg)的回收率为83%~103%,相对标准偏差(RSD)小于10%,方法的检出限为0.05 mg/kg。运用此方法分别对梨果皮和果肉中吡虫啉的残留动态进行研究,发现吡虫啉主要在梨果皮中残留,得到吡虫啉在果皮中的消解动态方程为:wt=w0×exp(-0.235t),半衰期是2.98 d。

Determination of Imidacloprid Residue and Its Distribution in Pears by SCX Solid-phase Extraction-High Performance Liquid Chromatography

A method was developed for the determination of imidacloprid residue in the pericarp and pulp of pear with SCX-solid phase extraction(SPE)-high performance liquid chromatography(HPLC).The sample was extracted with acetonitrile and the extract was clean-up with SCX-SPE after LLE with dichloromethane;the content of imidacloprid was determined by HPLC with diode-array detection.The average recoveries of imidacloprid in pear pericarp(spiked at 0.1,0.5,and 1 mg/kg) and pear pulp(spiked at 0.05,0.5 and 1 mg/kg) ranged from 83% to 103% with relative standard deviation(RSD<10%).The detection limit was 0.05 mg/kg.The results of the study of the degradation dynamic of imidacloprid residue indicated that the residue was mostly left in the pear pulp.