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目的评定采用气相色谱-质谱联用结合同位素稀释技术测定鱼类样品中指示性多氯联苯的不确定度,分析影响测量不确定度的各种因素。方法依据GB/T5009.190-2006《食品中指示性多氯联苯的测定》对鱼类中指示性多氯联苯进行测定,建立测量过程中各分量的数学模型,估算各不确定度分量对总不确定度的影响。结果置信概率P为95%时,鱼类样品中总PCBs的测定结果为(27.26±0.72)μg/kg,k=2。结论本方法不确定度主要来自添加内标的浓度和相对响应因子计算过程,样品称量及内标溶液量取的影响可以忽略不计。同位素内标的应用可有效控制分析过程对不确定度的影响。
Objective To assess the uncertainty of determination of PCBs in fish samples by gas chromatography-mass spectrometry coupled with isotope dilution and to analyze various factors that affect the uncertainty of measurement. Methods According to GB / T5009.190-2006 “Determination of Indicative PCBs in Food”, the instrumental PCBs in fish were measured, the mathematical model of each component in the process of measurement was established, and the components of each uncertainty were estimated Impact on total uncertainty. Results When the confidence probability P was 95%, the total PCBs in fish samples was (27.26 ± 0.72) μg / kg, k = 2. Conclusion The uncertainty of this method mainly comes from the calculation of the concentration of added internal standard and the calculation of relative response factor. The effects of sample weighing and internal standard solution volume are negligible. The application of isotope internal standard can effectively control the impact of the analysis process on the uncertainty.