GC-MS Determination of Residual Amounts of 11 Organophosphorus Pesticides in Sorghum Seeds

GC-MS was applied to the determination of residual amounts of 11 organophosphorus pesticides in sorghum seeds. The sample was sopped with H2O and extracted with acetonitrile, the extract was purified by C18 SPE column and Carb/PSA column. The eluate was taken for separation on HP-5MS chromatographic column and the contents of 11 organophosphorus pesticides were determined under SIM mode. External standard method was adopted in the determination. Linear relationships between values of peak area and mass concentration of the 11 organophosphorus pesticides were obtained in the range of 0.05-1.0 mg·L-1, with their detection limits (3S/N) in the range of 0.001-0.025 mg·kg-1. Test for recovery were made by addition of standard at 2 different concentration levels, values of recovery found were in the range of 81.3%-108%, with values of RSD′s (n=5) in the range from 1.5% to 8.0%.