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对采用气相色谱内标法测定鱼丸中的二十二碳六烯酸(DHA)含量的测量不确定度进行评定。通过建立测定过程中各分量的数学模型,分析、识别不确定度来源。其不确定度主要来源于校正因子、样品称量、十一碳酸甘油三酯内标溶液、重复测定、回收率等因素。在对各不确定度分量进行量化的基础上,合成得到测定结果的标准不确定度。当鱼丸的DHA含量为170.2 mg/100 g时,其合成标准不确定度和扩展不确定度分别为2.7 mg/100 g和5.4 mg/100 g。重复测定引入的不确定度分量对总不确定度的贡献最大。十一碳酸甘油三酯内标溶液浓度及添加体积、回收率、校正因子带来的不确定度分量也不容忽视。试样称量对总不确定度的贡献最小。本研究结果为采用该方法测定鱼丸中DHA含量提供理论依据。
The measurement uncertainty of determination of docosahexaenoic acid (DHA) in fish balls by gas chromatography internal standard method was evaluated. By establishing the mathematical model of each component in the measurement process, the source of the uncertainty is identified and analyzed. The uncertainty comes mainly from the correction factor, sample weighing, eleven capric triglyceride internal standard solution, repeated determination, recovery and other factors. Based on the quantification of each uncertainty component, the standard uncertainty of the measurement result is synthesized. When the fish meal has a DHA content of 170.2 mg / 100 g, the synthetic standard uncertainty and extended uncertainty are 2.7 mg / 100 g and 5.4 mg / 100 g, respectively. The uncertainty component introduced by repeated measurements contributed the most to the total uncertainty. Undecane triglyceride internal standard solution concentration and volume added, recovery, the uncertainty factor caused by the correction factor can not be ignored. The sample weight contributes the least to the total uncertainty. The results of this study provide a theoretical basis for the determination of DHA content in fish balls by this method.