气相色谱-质谱法测定芥蓝中虫螨腈残留量的不确定度评定

目的评定气相色谱-质谱法测定芥蓝中虫螨腈的不确定度。方法采用气相色谱-质谱法(GB23200.8-2016)对芥蓝中虫螨腈残留量进行测定,建立测量不确定度的数学模型,计算检测过程中不确定度分量,合成扩展不确定度。结果当芥蓝中虫螨腈残留量为0.091mg/kg时,其扩展不确定度为0.0060mg/kg(k=2)。结论标准溶液配制过程引入的不确定度贡献率最大,使用的量具标称容量越小引入的不确定度越大,使用体积越小引入的不确定度越大。实验室可通过选择合适的量具、增加平行样品测定,提高人员操作熟练度及稳定性等来减小测量不确定度。

Uncertainty evaluation for determination of chlorfenapyr residues in cabbage mustard by gas chromatography-mass spectrometry

Objective To evaluate the uncertainty for the determination of chlorfenapyr in cabbage by gas chromatography-mass spectrometry. Methods Gas chromatography-mass spectrometry (GB 23200.8-2016) was used to determine chlorfenapyr residues in cabbage, a mathematical model of measurement uncertainty was established, uncertainty components in the detection process were calculated, and the extended uncertainty was synthesized. Results When the residue of chlorfenapyr was 0.091 mg/kg, the expanded uncertainty was 0.0060 mg/kg (k=2). Conclusion The uncertainty contribution rate introduced in the preparation process of standard solution is the largest. The smaller the nominal capacity of the measuring tool is, the greater the uncertainty will be, and the smaller the used volume is, the greater the uncertainty will be. The laboratory can reduce the uncertainty of measurement by selecting appropriate measuring tools, increasing parallel sample measurement, and improving the proficiency and stability of personnel.