气相色谱质谱联用技术测定大米中溴虫腈的不确定度评定

Uncertainty evaluation for determination of chlorfenapyr in rice by gas chromatography-mass spectrometry

目的评定气相色谱质谱联用技术测定大米中溴虫腈的不确定度。方法通过分析测量过程确定不确定度的来源;通过统计学方法,从质量浓度、体积、质量和仪器测量重复性等方面量化不确定度;最后计算合成不确定度和扩展不确定度。结果当大米中溴虫腈含量为2.18μg/kg时,扩展不确定度U=0.26μg/kg(k=2)。结论气相色谱质谱联用技术测定大米中溴虫腈的不确定度主要来源是标准曲线拟合,其次是重复性的测定;在标准溶液的配制过程中,要合理制定标准曲线线性范围,在样品的前处理过程中需要更加规范的实验操作来减小实验重复性引起的不确定度,并适当增加重复性次数,从而保证实验结果的可靠性。

Objective To evaluate the uncertainty for the determination of chlorfenapyr in rice by gas chromatography-mass spectrometry. Methods The sources of uncertainty were determined by analyzing the measurement process. The uncertainty was quantified from the aspects of mass concentration, volume, mass and instrument measurement repeatability by statistical methods. Finally, the synthetic uncertainty and extended uncertainty were calculated. Results When the content of chlorfenapyr in rice was 2.18 μg/kg, the expansion uncertainty U=0.26 μg/kg(k=2). Conclusion The main source of uncertainty for determination of chlorfenapyr in rice by gas chromatography-mass spectrometry is standard curve fitting, followed by repeatability determination. In order to ensure the reliability of the experimental result, we should develop the linear range of standard curves reasonably in the configuration process of standard solution, standardize the experimental operation in the pretreatment process of samples to reduce the uncertainty caused by experimental repeatability and increase the repeatability times appropriately, so as to ensure the reliability of experimental results.