Determination of 32 weedicides and pesticides in foods by gas chromatography-mass spectrometry and selected ion monitoring

Objective:To establish a method for determination of organophosphorus,organochlorine,carbamate and weedicide pesticides in foods by gas chromatography-mass spectrometry(GC-MS) and selected ion monitoring(SIM).Methods:The pesticides were extracted with acetone and dichloromethane.The extract was warmed with water at 80℃,circumrotated and evaporated until it was nearly dry.Then it was cleaned-up by Envi-Carb column and Sep-Pak-NH2 column.The analysis was performed by GC-MS and SIM.Retention time and specific ions were used to confirm the pesticides.Results:The calibration curves of 32 pesticides were linear(correlation coefficient r0.99)within the range of 0.05～1.0 μg/ml.The recoveries were 90%～96%,the relative standard deviations(RSD) of the method was 10% for each case,and the limit of determination(LOD),defined in terms of 3 times baseline noise,was 0.005 mg/kg.Conclusion:The method is suitable for determining pesticides in foods with satisfactory sensitivity,accuracy and precision.