气相色谱法测定鱼肉中指示性多氯联苯的不确定度评定
Uncertainty Evaluation of Indicative Polychlorinated Biphenyls in Fish by Gas Chromatography
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摘要: 为了提高实验室检测结果的准确性，对气相色谱法测定鱼肉中指示性多氯联苯含量进行了不确定度的评定。依据食品安全国家标准GB 2762-2022《食品安全国家标准食品中污染物限量》，识别“被测量”为样品中“以2,4,4’-三氯联苯( PCB 28) 、2,2’,5,5’-四氯联苯（PCB52）、2,2’,4,5,5’-五氯联苯（PCB101）、2, 3’,4,4’,5-五氯联苯（PCB118）、2,2’,3,4,4’,5’-六氯联苯（PCB138）、2,2’,4,4’,5,5’-六氯联苯（PCB153）和 2,2’,3,4,4’,5,5’-七氯联苯（PCB180）总和计”的多氯联苯含量，根据“被测量”及检测标准，重新建立多氯联苯测量模型，分析测量模型中对结果有影响的不确定度分量，并进行评定。经评定，质控鱼肉样品中多氯联苯的测量结果为149.1 μg/kg，相对扩展不确定度Ur=2.9%, k=2。不确定度贡献为：测量重复性70.8%、称样质量0.025%、加入内标体积1.8%、样品溶液中各目标物浓度比值之和27.3%。Abstract: In order to ensure the accuracy of laboratory test results, the uncertainty of the determination of indicative polychlorinated biphenyls in fish by gas chromatography was evaluated. According to the national Food Safety standard, National Food Safety Standard Maximum Levels of Contaminants in Foods (GB 2762-2022), the content of PCB28, PCB52, PCB101, PCB118, PCB138, PCB153 and PCB180) in the "measured" samples was determined as the total content of PCBs. Then, the polychlorinated biphenyls (PCBs) measurement model was re-established according to the "measured" and detection standard, and then the weight of uncertainty affected by the measurement model on test results were analyzed and evaluated. After evaluation, the measurement result of PCBs in quality control fish samples was 149.1 μg/kg, and the relative extended uncertainty was Ur=2.9% k=2. The contribution of uncertainty was: measurement repeatability 70.8%, sample weight 0.025%, internal standard volume 1.8%, sum of concentration ratios of each target in sample solution 27.3%.
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