QuEChERS-液相色谱-质谱联用法测定草莓中烯酰吗啉残留量的不确定度评定

Evaluation of uncertainty in determination of dimethomorph residue in strawberry by QuEChERS-liquid chromatography-tandem mass spectrometry method

[目的]评定使用GB 23200.121—2021《植物源食品中331种农药及其代谢物残留量的测定液相色谱-质谱联用法》测定草莓中烯酰吗啉残留量的不确定度。[方法]通过建立测量模型,识别和量化各不确定度分量,计算在最大残留限量0.05 mg/kg含量水平下的合成标准不确定度和扩展不确定度。[结果]在置信概率p为95%时,取包含因子k为2,扩展不确定度为0.006 mg/kg,测量结果表示为(0.050±0.006) mg/kg,k为2。[结论]该方法的测量不确定度主要来自标准曲线拟合和标准溶液配制,贡献率分别为43%和32%,而由样品称量引入的不确定度分量最小,仅占1%。本模型可为使用QuEChERS-液相色谱-质谱联用法测定农药残留量的不确定度评定提供参考。

[Aims] This study aims to evaluate the uncertainty in determination of dimethomorph residue in strawberry according to GB 23200.121-2021 ‘National food safety standard—Determination of 331 pesticides and metabolites residues in foods of plant origin-Liquid chromatography-tandem mass spectrometry method’. [Methods] A measurement model was established to identify and quantify the various uncertainty components, then the combined standard uncertainty and expanded uncertainty were calculated at the maximum residue limit(MRL) level of 0.05 mg/kg.[Results] The expanded uncertainty was 0.006 mg/kg at confidence probability p=95%(coverage factor k=2), the measurement result was expressed as follow:(0.050±0.006) mg/kg, k=2. [Conclusions] The main sources of measurement uncertainty were fitting of calibration curve and preparation of standard solutions which accounts for 43 and 32%,respectively. The lowest uncertainty component was introduced by sample weighting, accounting for only 1%. This model could provide a reference for uncertainty evaluation in determination of pesticide residues by QuEChERS-liquid chromatography-tandem mass spectrometry method.