GPC-GC Determination of Residual Amounts of 55 Organophosphorus Pesticides in Sunflower Seeds

A method of GC for determination of residual amounts of 55 organophosphorus pesticides in sunflower seeds was proposed. The sample was extracted with a mixture of ethyl acetate and cyclohexane (1+1), and the extracts obtained were purified to remove the macromolecular impurities by gel permeation chromatography (GPC), using Bio-Beads S-X3 GPC column and the same mixture of ethyl acetate and cyclohexane (1+1) as mobile phase. The 55 organophosphorus pesticides in the eluate were separated on DB-1701 (30 m×0.25 mm, 0.25 μm) column and determined by flame photometric detector. Linear relationships between values of peak area and mass concentration of the 55 organophosphorus pesticides were kept in definite ranges, with detection limits (10S/N) in the range of 0.002 5-0.05 mg·kg-1. Recovery and precision of the method were tested at 3 concentration levels, giving results of recovery in the range of 53.5%-119% and RSD′s (n=6) less than 14%.