Abstract: Various pretreatment techniques were compared because of complex ground substance in aquatic products. Then a method was developed for the determination of residues of sixteen congeners trace polychlorinated biphenyls based on the selected pretreatment technique. Samples were extracted with n-hexane, defatted with sulfuric acid, purified by silica column, and determined by gas chromatography and electron capture detection with external standard method for quantitative analysis. Results showed that the recoveries of standard addition levels are 71.0%～104.9%, the relative standard deviations are all below 6.86%, and the limits of detection are 0.08～0.21 ng/g.

Key words: aquatic products, trace polychlorinated biphenyls, GC-ECD