气相色谱法测定大白菜中百菌清农药残留的不确定度评定

Evaluation of Uncertainty in the Determination of Chlorothalonil Pesticide Residues in Chinese-Cabbage by Gas Chromatography

目的:评定气相色谱法测定大白菜中百菌清农药残留的不确定度。方法:参照《蔬菜和水果中有机磷、有机氯、拟除虫菊酯和氨基甲酸酯类农药多残留的测定》(NY/T 761—2008)标准测定大白菜中百菌清农药残留,并建立数学模型,分析不确定度的来源。结果:6次平行添加测定大白菜中百菌清平均含量为0.1874 mg·kg^(-1),置信概率为95%时,测定的扩展不确定度为0.0184 mg·kg^(-1)(k=2)。结论:大白菜中百菌清农药残留测量结果引入的不确定度主要有标准曲线拟合、试剂移取、样品重复测定、标准物质、定容和称量等。其中,标准曲线拟合引入的不确定度最大,样品测量引入不确定度最小。

Objective:To evaluate the uncertainty evaluation of chlorothalonil pesticide residues in Chinese cabbage by gas chromatography.Method:According to the NY/T 761—2008 standard,the pesticide residues of chlorothalonil in Chinese cabbage were determined,and a mathematical model was established to analyze the source of uncertainty.Result:The average content of chlorothalonil in Chinese cabbage was 0.1874 mg·kg^(-1)by 6 parallel additions.When the confidence probability was 95%,the expanded uncertainty of the determination was 0.0184 mg·kg^(-1)(k=2).Conclusion:The uncertainty introduced in the measurement results of chlorothalonil pesticide residues in Chinese cabbage mainly includes standard curve fitting,reagent pipetting,repeated sample determination,standard material,constant volume and weighing.Among them,the uncertainty introduced by the standard curve fitting is the largest,and the uncertainty introduced by the sample measurement is the smallest.