Analysis Method Study on 839 Pesticide and Chemical Contaminant Multiresidues in Animal Muscles by Gel Permeation Chromatography Cleanup, GC/MS, and LC/MS/MS

The paper reports the study of gel permeation chromatography (GPC), gas chromatography/mass spectrometry (GS/MS), and column chromatography tandem MS (LC/MS/MS) for 839 pesticides and chemical contaminants, through which a GPC data bank has been established for 744 pesticides, a GC/MS data bank for 541 pesticides, and an LC/MS/MS data bank for 464 pesticides. On the basis of this study, a new method for quantitative determination of 587 pesticide residues in animal muscles such as beef, mutton, pork, chicken, and rabbit has been established using GPC cleanup followed by GC/MS and LC/MS/MS. In the method, 10 g animal samples were mixed with 20 g sodium sulfate and extracted twice with 35 mL cyclohexane-ethyl acetate (1 + 1) by blender homogenization followed by centrifugation, filtration, and concentration. An equivalent of 5 g sample was injected into a 400 x 25 mm S-X3 GPC column, with cyclohexane-ethyl acetate (1 + 1) as the mobile phase at a flow rate of 5 mL/min. The 22-40 min fraction was collected for subsequent analysis. For the 478 pesticides determined by GC/MS, the portions collected from GPC were concentrated to 0.5 mL and exchanged twice with 5 mL hexane. For the 379 pesticides determined by LC/MS/MS, the portions collected from GPC were dissolved with acetonitrile-water (60 + 40) after taking the extract to dryness with nitrogen gas. At the limit of quantification (LOQ) and 10 LOQ fortification levels of 0.1-16 000 microg/kg, recoveries were within 40-130%, among which 563 pesticide recoveries were between 60 and 130%, accounting for 96% of the compounds; 24 analytes were recovered between 40 and 60%, accounting for 4% of the compounds. The relative standard deviation was below 30% for all 587 pesticides. The limits of detection for the method were 0.1-1600 microg/kg. In comparison with GC/MS, LC/MS/MS increased the detection sensitivity 2-1000 times for 236 pesticides.