GC Determination of Residual Amounts of 22 Polychlorobiphenyl′s in Vegetables

Vegetable sample was extracted with a mixture of acetone and n-hexane (1+1) in the ASE 200 Microwave Extractor.The extract was dehydrated with anhydrous Na2SO4 and evaporated to near dryness.The residue was dissolved in n-hexane and purified by passing through Florisil column.The column was eluted with n-hexane,and the eluates collected were combined and evaporated to a volume of 2.0 mL which were used for GC analysis.Linear relationships between values of peak area and mass concentration of monomers of the 22 polychlorobiphenyl′s (PCBP′s) were obtained in definite ranges,with correlation coefficients over 0.999 as shown by their linear regression equations.Tests for recovery were made by adding mixed standard solutions of the 22 PCBP monomers to a same matrix sample of Chinese cabbage,values of average recovery found were in the range of 84.0% to 99.0%.Values of RSD′s (n=6) found at one concentration level of the mixed standard solution were in the range of 0.90%-2.69%.