鸡肉中亚胺硫磷等26种农药残留的液相色谱串联质谱法不确定度的评定

Uncertainty evaluation of 26 pesticide residues including phosmet in chicken by liquid chromatography-tandem mass spectrometry

采用液相色谱-串联质谱法测定鸡肉中的26种农药残留量,分析不确定度来源,并对不确定度各分量进行评定。通过空白基质添加8次重复测定,考察A类不确定度;通过对实验过程中的前处理过程中的样品称量、提取试剂和温度,到标准物、校准曲线拟合和实验过程中温度引入的不确定度的全面分析,评价B类不确定度;取置信水平P=95%,k=2,最终给出液相色谱串联质谱法测定鸡肉中26种农药含量的扩展不确定度。结果表明,引起本实验室过程相对不确定度的主要因素为标准物质纯度,其值为0.025和0.01、标准物质配制达到0.01以上,校准曲线拟合,实验重复性和前处理过程引入的不确定相对较小,特别是温度引起的不确定度可忽略。因此在实验过程中,购买有证标准物质、提高检测人员操作水平,可有效提降低实验过程中引入的相对不确定度。该研究可为动物源性食品中农药残留测定不确定度的评定提供依据,也为实验室内部质量控制提供技术支撑。

The liquid chromatography-tandem mass spectrometry was adopted,and26 pesticide residues in chicken were determined,and the source of uncertainty were analyzed,and the components of uncertainty were evaluated.The uncertainty of class Awas measured by adding 8 replicates of blank matrix.Sample weighing,extraction reagent and temperature in the pre-treatment process of the experiment,and standard substance,calibration curve fitting andthe uncertainty introduced by temperature in the experiment were comprehensively analyzed,and the uncertainty of class B was evaluated.The P=95%,K=2 weretakenas confidence level,and the extended uncertainty of the determination of 26 pesticides in chicken by liquid chromatography-tandem mass spectrometry was finally given.The results showed that the main factor causing the relative uncertaintyin the process of the laboratorywas the purity of the standard substance,and their values were 0.025 and 0.01,andthe preparation of the standard substance reached more than 0.01.The uncertainty introduced by the calibration curve fitting,experimental repeatability and pretreatment processwas relatively small,especially the uncertainty caused by temperature could be ignored.Therefore,in the experimental process,the certified standard substances were purchased,and the operation level of tester was improved,and the relative uncertainty introduced in the experimental process could be effectively reduced.This study could provide a basis for the evaluation of the uncertaintyin the determination of pesticide residuesin animal-derived food,and it also provided technical support for the internal quality control of the laboratory.