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.

Validation study on 660 pesticide residues in animal tissues by gel permeation chromatography cleanup/gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry.

A new method using gel permeation chromatography (GPC) cleanup followed by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS-MS) has been established for quantitative determination of 437 pesticide residues in animal tissues such as beef, mutton, pork, chicken, and rabbit. Based on an appraisal of the characteristics of both GC-MS and LC-MS-MS, validation experiments were conducted for 660 pesticides. In the method, 10 g animal samples were mixed with 20 g sodium sulfate and extracted with 35 mL of cyclohexane+ethyl acetate (1+1) twice by blender homogenization, centrifugation, and filtration. Evaporation was conducted and an equivalent of 5 g sample was injected into a 400 mm 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 368 pesticides determined by GC-MS, the portions collected from GPC were concentrated to 0.5 mL and exchanged with 5 mL hexane twice. For the 69 pesticides 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. In the linear range of each pesticide, the correlation coefficient was r > or = 0.98, exceptions being dinobuton, linuron, and fenamiphos sulfoxide. At the low, medium and high three fortification levels of 0.2-4800 microg/kg, recoveries fell within 40-120%, among which 417 pesticides recoveries between 60% and 120%, accounting for 95%, 20 analytes between 40% and 60%, accounting for 5%. The relative standard deviation was below 28% for all 437 pesticides. The limits of detection for the method were 0.2-600 microg/kg, depending on each pesticide.

Simultaneous determination of 16 sulfonamides in honey by liquid chromatography/tandem mass spectrometry.

A method is described for the determination of 16 sulfonamides in honey. Samples are dissolved in phosphoric acid solution (pH2), cleaned up with 2 solid-phase extraction (SPE) cartridges, an aromatic sulfonic cation-exchange cartridge and an Oasis HLB SPE cartridge, and analyzed both qualitatively and quantitatively by liquid chromatography/tandem mass spectrometry (LC/MS/MS) under the selected conditions. Without exception, calibration curves were linear (r = > 0.995), when sulfamethizole was between 1.0 and 25.0 microg/kg; sulfacetamide, sulfapyridine, sulfadiazine, sulfachloropyridazine, sulfamethoxazole, sulfamerazine, sulfisoxazole, sulfamonomethoxine, and sulfadoxine were between 2.0 and 50.0 microg/kg; sulfamethoxypyridazine, sulfadimethoxine, and sulfathiazole were between 4.0 and 100.0 microg/kg; sulfamethazine and sulfameter were between 8.0 and 200.0 microg/kg; and sulfaphenazole was between 12.0 and 300.0 microg/kg. Average recoveries at 4 fortification levels in the range of 1.0-300 microg/kg in honey were 70.9-102.5%, and relative standard deviations were 2.02-11.52%. The limits of quantitation for the 16 sulfonamides were between 1.0 and 12.0 microg/kg, with the LC/MS/MS method.