Determination of Restricted Pesticides-Carbamates Illegally Added in Pesticide Products by High Performance Liquid Chromatography

Pesticide sample (0.400 g) was dissolved ultrasonically in 80 mL of methanol for 10 min, and the solution was diluted to 100.0 mL with methanol. An aliquot of the sample solution (ca. 50 mL) was taken and centrifuged for 5 min. The supernatant was taken and filtered through a filtering membrane of 0.45 μm. The filtrate was used for HPLC analysis. Besil C₁₈-B column was selected as stationary phase with column temperature at 30℃. Mixtures of (A) water and (B) methanol in various proportions were used as mobile phase in gradient elution with a flow rate of 1 mL·min^-1, to effect a satisfactory separation of the 12 carbamates. UV-detection was made at the wavelength of 215 nm using diode array detector. As shown by the results, linear relationships between values of peak area and mass concentration of the 12 carbamate pesticides in the range of 5.0-100.0 mg·L^-1, with detection limits (3S/N) in the range of 0.1-0.2 mg·kg^-1. Test for recovery by standard addition method was made using a blank pesticide sample as matrix, giving results in the range of 97.2%-106%, and RSDs (n=6) ranged from 1.5% to 3.8%.