RP-HPLC Determination of Residual Amounts of Abamectin in Longan

Abamectin in longan was extracted with acetonitrile and fitered. The extract was shaked with solid NaCl. An aliquot of the acetonitrile phase was taken,and evaporated to dryness by N2-blowing in a hot water bath at 60 ℃. The residue was taken and made up to 2.0 mL with methanol,and the solution obtained was used for HPLC determination. The Symmetry C18 column was used as stationary phase,and mixture of methanol and H2O (90+10) was used as mobile phase with flow-rate of 1.0 mL·min-1. UV detection at 245 nm was adopted in the measurement. Linear relationship between values of peak area and concentration of abamectin was obtained in the range of 0.01-2.0 mg·L-1,and detection limit (3S/N) of the method found was 0.005 mg·kg-1. Eight samples of longan were analyzed by the proposed method,and recovery was tested by adding standard solution of abamectin to these samples,values of recovery found were in the range of 87%-92%,and values of RSD′s (n=5) of the results were in the range of 1.79%-4.89%.