Simultaneous GC Determination of Chlorothalonil,Triadimefon and Pyrethrin Pesticide Residues in Buckwheat

Gas chromatography was applied to the determination of residual chlorothalonil,triadimefon and pyrethrin pesticides in buckwheat.The sample was extracted with a mixture of petroleum ether and acetone(4+1),and the extract obtained was purified and concentrated on chromatographic column.The eluate from the chromatographic column was used for GC (with ECD) analysis.Linearity ranges of chlorothalonil,triadimefon and 4 pyrethrin pesticides were kept in the range of 0.02-5.0 mg·L-1,with detection limits (3S/N) less than 0.02 mg·L-1.Tests for recovery and precision were made by standard addition method at 3 different concentration levels,values of recovery found were in the range of 80.4%-111.6% and values of RSD′s (n=8) were less than 8.0%.