气相色谱-串联质谱法检测香菇中残留的福美双、丙森锌和代森联

目的建立福美双、丙森锌、代森联3种农药残留在香菇样品中的气相色谱-串联质谱检测方法。方法用带有强螯合作用的碱性缓冲溶液将不溶于水的二硫代氨基甲酸重金属盐转化为不同的水溶性钠盐,在离子对甲基化的作用下将二硫代氨基甲酸钠盐转化为不同的甲酯化合物,采用DB-5MS毛细管气相色谱柱(30 m×0.25 mm,0.25μm)分离,选择离子扫描方式进行气相色谱-串联质谱检测,工作曲线外标法定量。结果衍生后的二硫代氨基甲酸盐类农药在一定范围内(福美双0.05~1.00μg/mL;丙森锌和代森联0.25~5.00μg/mL),其浓度与气质联用仪相应定量离子的响应峰面积呈良好的线性关系。福美双、丙森锌、代森联的检出限分别为0.01、0.05、0.05 mg/kg,平均回收率为76.98%~93.52%,相对标准偏差最大为11.54%(n=6)。结论该方法操作简便、灵敏度高、定量准确可靠,各项指标均符合农药残留检测的要求。

Determination of thiram,propineb and metiram in mushroom by gas chromatography-mass spectrometry

OBJECTIVE To establish a method for determination of thiram,propineb and metiram in mushroom samples by gas chromatography-mass spectrometry(GC-MS).METHODS Insoluble heavy metal salts were converted into water-soluble sodium salts by alkaline buffer with strong chelating agents.Dithiocarbamates can be converted into different methyl ester compounds with ion pair methylation.The GC separation was performed on a DB-5 MS capillary column(30 m×0.25 mm,0.25μm).The pesticides were detected by GC-MS with selective ion monitoring(SIM)and quantified by external standard of working curve method.Methodsological verification was carried out based on optimized sample pretreatment and GC-MS condition.RESULTS The concentrations of dithiocarbamates exhibited a good linear relationship with GC-MS within a certain range.The limits of detection of thiram,propineb and metiram were 0.01,0.05 and 0.05 mg/kg,respectively.Furthermore,the average recoveries were from 76.98%to 93.52%,and the maximum relative standard deviation was 11.54%(n=6).CONCLUSION This method is simple,sensitive,accurate and reliable.All the indices meet the requirements of pesticide residue detection.