Determination of lambda-cyhalothrin residue in tea and soil using gas chromatography

A gas chromatographic (GC) method was established for the determination of lambda-cyhalothrin residue in tea and soil. Tea and soil samples were extracted with hexane, separated by capillary column and determined by gas chromatography-electron capture detector (GC-ECD). The average recoveries of lambda-cyhalothrin in tea and soil were 89.0% -94.1% and 89.8% -94.7%, respectively at the spiking levels of 0.02 to 2.00 mg/kg. The corresponding relative standard deviations (RSDs, n =5) were 3.0% -4.9% and 2.5% -4.2%, respectively. The limit of detection (S/N = 3) was 0.002 mg/kg for lambda-cyhalothrin. The degradations of 2.5% lambda-cyhalothrin microemulsion in tea and soil in Changsha, Hunan were investigated and the degradation equations were Y = 3.1996e(-0.3394x) and Y = 0.1224e(-0.1036x) with the correlation coefficients of 0.9956 and 0.9247, respectively. The half-lives of lambda-cyhalothrin in tea and soil were 2.04 days and 6. 69days, respectively.