| A GC/ECD method for the simultaneous analysis of thiamethoxam,chlorfenapyr and lambda-cyhalothrin residues in tea and soil was developed and validated.The samples were extracted with acetonitrile after water soaking,and purified by QuEChERS method using PSA,GCB and Florisil as adsorbents,then determined by GC/ECD.The result showed that the calibration curves were linear in the ranges of 0.50-400 μg/L for thiamethoxam,0.20-100 μg/L for chlorfenapyr and 0.40-200 μg/L for lambda-cyhalothrin,with correlation coefficients more than 0.99.The limits of detection（LODs） for thiamethoxam,chlorfenapy and lambda-cyhalothrin were 0.25,0.05,0.10 μg/L,respectively.The average recoveries in tea and soil at three spiked levels were between 62% and 108% with RSDs（n=5）no more than 15.8%,and the limits of quantitation（LOQs） were lower than 10 μg/kg.This method is easy,quick,effective and safe,and can meet the requirements for simultaneous residue determination of thiamethoxam,chlorfenapyr and lambda-cyhalothrin in tea and soil samples. |