气相色谱-火焰光度检测器法检测果蔬样品中3种二硫代氨基甲酸盐类农药残留

目的建立检测福美铁、丙森锌、代森锰农药残留的气相色谱-火焰光度检测器(硫滤光片)GC-FPD(S)]测定方法,提高该类农药的检测专一性。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可溶于水的钠盐,在离子对甲基化的作用下将二硫代氨基甲酸钠盐转化为可供GC-FPD(S)测定的含硫酯类物质,优化样品前处理技术和色谱检测条件,并进行方法学论证。结果衍生后的二硫代氨基甲酸盐类农药在一定范围内,其浓度的平方与GC-FPD(S)的响应峰高呈良好的线性关系。福美铁、丙森锌、代森锰的最低检出浓度分别为0.1、0.5、0.5 mg/kg,平均回收率为75.3%～94.6%,相对标准偏差最大为14.1%。结论该方法操作简便、定量准确可靠,各项指标均符合农药残留检测的要求。

Determination of three dithiocarbamate pesticides residues in fruit and vegetable samples by gas chromatography-flame photometric detector

Objective A gas chromatography-flame photometric detector (sulfur filter) GC-FPD(S)] method for the residues determination of ferbam, propineb and maneb in fruit and vegetable samples was established. The method could improve the specificities of detection for dithiocarbamates. Methods By alkaline buffer with strong chelating agents, insoluble heavy metal salts were converted into water-soluble sodium salts. With ion pair methylation, dithiocarbamates could be converted into esters which could be used for GC-FPD(S). Methodological verification was carried out based on optimized sample pretreatment and chromatographic conditions. Results The square of dithiocarbamates concentration exhibited a good linear relationship in certain range. The detection limits of fenbam, propineb and maneb were 0.1,0.5, and 0.5 mg/kg respectively. Furthermore, the average recoveries were 75.3%-94.6%, and the maximum relative standard deviations was 14.1%. Conclusion This method was simple, accurate and reliable for residues detemination of dithiocarbamates pesticides in fruit and vegetable samples. All indexes meet the requirements of pesticide residue detection.