加速溶剂萃取—气相色谱—串联质谱法同时测定种植土壤中6种广谱杀菌类农药的残留量

Simultaneous Determination of Residues of 6 Broad Spectrum Bactericidal Pesticides in Planting Soil by Gas Chromatography-Tandem Mass Spectrometry with Accelerated Solvent Extraction

以题示方法测定种植土壤中6种广谱杀菌类农药(吡唑醚菌酯、戊唑醇、氟硅唑、氟菌唑、肟菌酯和百菌清)的残留量。随机采集种植土壤样品,经除杂、风干、研磨和过筛后,分取10 g,加入硅藻土5 g,研磨均匀,转移至加速溶剂萃取池中,在萃取温度70℃时按照设定好的参数进行萃取。萃取液过活化好的弗罗里硅土固相萃取柱,所得洗脱液于70℃氮吹至近干,用正己烷稀释至1 mL后注入气相色谱仪。6种农药在Rtx-5MS色谱柱上进行程序升温分离,用配电子轰击离子源的串联质谱仪检测,基质匹配法定量。结果显示:6种农药可在20 min内完成分离,其质量浓度均在0.05~2.0 mg·L^(-1)内与其对应的峰面积呈线性关系,检出限(3S/N)为0.005~0.012 mg·kg^(-1);加标回收率为89.3%~102%,测定值的相对标准偏差(n=6)为1.8%~4.0%。

The residues of the 6 broad spectrum bactericidal pesticides(pyraclostrobine, tebuconazole, flusilazole, fluconazole, trifloxystrobin and chlorothalonil) in planting soil were determined by the title method. Planting soil sample was randomly collect, removed impurities, dried by air, grinded and sieved, and an aliquot(10 g) was taken, and mixed with 5 g of diatomite. The mixture was grinded evenly, transferred to the accelerated solvent extraction pool, and extracted according to the set parameters at the extraction temperature of 70 ℃ by nitrogen. The extract was passed through the activated magnesiumtrisilicate solid phase extraction column, and the obtained eluate was blown to nearly dry at 70 ℃ by nitrogen, and diluted to 1 mL with n-hexane. The above solution was injected into the gas chromatograph, and the 6 pesticides were separated on Rtx-5 MS chromatographic column under temperature-programmed conditions, detected by tandem mass spectrometry with electron impact ion source, and quantified by matrix matching method. It was shown that the 6 pesticides could be separated within 20 min, and their mass concentrations were linearly related with corresponding peak areas in the range of 0.05-2.0 mg·L^(-1), with detection limits(3 S/N) in the range of 0.005-0.012 mg·kg^(-1). Test for recovery was made by standard addition method, giving recoveries in the range of 89.3%-102%, and RSDs(n=6) of the determined values ranged from 1.8% to 4.0%.