Abstract:

Two sample pretreatment methods were developed and applied to determine 111 residues of pesticides in aquatic products. For Method Ⅰ, the residues were extracted from homogenized tissue with acetone-ethylacetate-n-hexane (1∶1∶1, v/v/v), and then were redissolved in acetonitrile; for Method Ⅱ, the residues were extracted from homogenized tissue with acetonitrile-water under ultrasonication, and then were separated by liquid-liquid partition. The supernatants were purified using solid phase extraction (Envi-18 and PSA columns) prior to the GC-MS analysis. The determination was performed in selected ion monitoring (SIM) mode with the external calibration for quantitative analysis. Under the optimal conditions, the detection limits (S/N=3) for residues of pesticides were in the ranges of 0.001-0.026 mg/kg. The recoveries of Method Ⅰ for the spiked standards at concentration of 0.25 mg/kg were 72%-113% with the relative standard deviations (RSDs) of 3.4%-12.1%. The recoveries of Method Ⅱ were 51%-127%, among which the recoveries for 94% pesticides were between 70% and 120% with the RSDs of 3.2%-13.8%.

Key words: aquatic products , gas chromatography-mass spectrometry (GC-MS), multiresidual pesticides, sample pretreatment, solid phase extraction （SPE）