A method was developed for the rapid determination of 32 pesticide residues

including organ ochlorine

organophosphate and pyrethroid pesticides

in milk based on gas chromatography-ion trap tandem mass spectrometry.Electron impact ionization or chemical ionization were selected for the analytes with different sensitivities.Experimental parameters influencing the behaviours of compounds in the analysis of MS/MS were investigated and optimized.The mechanisms for the influencing factors were also discussed.Under the optimal conditions

the calibration curves for 32 pesticides were linear in the ranges of 25（10）-500（200） μg/L with correlation coefficients more than 0994.The method detection limits（MDL） for fention and chlorpyriphos were 1.7 μg/kg and 2.8 μg/kg

respectively

while those for the other pesticides were in the range of 0.026-1.2 μg/kg.The recoveries for 32 pesticides at two spiked levels of 50 and 200 μg/kg（organochlorine pesticides were spiked at 20 and 100 μg/kg） ranged from 71.5% to 116% with relative standard deviations（RSDs） of 1.9%-14%.The proposed method was applied in the detection for real samples

and could reduce the possibility of false positive results with strong anti interference.