DEGRADATION DYNAMICS OF IMIDACLOPRID IN TEA LEAVES AND TEA GARDEN SOIL

A determination method of the residue and degradation dynamics of imidacloprid in tea leaves and in tea garden soil are described in this paper.Samples of fresh tea leaves and tea garden soil were extracted with dichloromethane,and the extracts were purified on aa Al_2O_3 column,followed by imidacloprid determination using HPLC with a DAD detector.The recovery rate was 75.8% to 89.1% for fresh tea leaves and 81.8% to 105.1% for the soil,with a V.C.of 3.8%～5.5% and 5.0%～5.9%,respectively.The minimum detectable concentration was 0.01 mg/kg for tea leaves and 0.003 mg/kg for the soil.The degradation half-life of imidacloprid was 1.9～2.2 days for tea leaves and 3.7～2.8 days for the soil,thus the degradation speed being faster in tea leaves than in the soil.