GC Determination of Residual Amounts of 11 Pesticides in Vegetables of Complex Matrixes

Eleven pesticides of residual amounts (including BHC,DDT,tecnazene,quirtozene,aldrin and etc.) were extracted from samples of vagetables of complex matrixes with mixed solvent of acetone and n-hexane (mixed in the ratio of 1 to 1 by volume),and partitioned with 20 g·L-1 Na2SO4 solution. The n-hexane extract was purified by shaking with conc. H2SO4. After removing the H2SO4 phase,the hexane phase was washed with 20 g·L-1 Na2SO4 solution,and dehydrated with anhydrous Na2SO4. Then the solution in n-hexane was evaporated to near dryness by rotary evaporation under 13 kPa. The residue was taken and made up to 1.0 mL with n-hexane and used for GC determination. After separation on the DB 1701 capillary column,GC determination was carried out with μ-ECD. Recovery tests were made at 2 concentration levels by addition of mixed standard solution of the 11 pesticides to 4 kinds of vegetables as the matrixes,results of recovery found were in the range from 81.6% to 97.1%,with RSD′s (n=6) less than 7.5%. Detection limit (3S/N) of the method found was 0.5 μg·kg-1.