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目的对硫酸锌返滴定法测定食品添加剂磷酸二氢钙含量的测量不确定度进行评定,确保检测结果准确可靠。方法按照测量不确定度评定的通用规则,建立了数学模型,分析了方法中的不确定度分量及其来源,计算了各分量的不确定度,最后计算出了检测结果的合成标准不确定度和扩展不确定度。结果扩展不确定度为0.10%,K=2。结论标准溶液产生的相对标准不确定度及用硫酸锌溶液滴定产生的不确定度是硫酸锌返滴定法测定食品添加剂磷酸二氢钙含量的主要影响因素。
OBJECTIVE To evaluate the uncertainty of measurement of calcium dihydrogenphosphate (Ca2 +) content in food additives by back titration with zinc sulfate to ensure the test results are accurate and reliable. Methods According to the general rules of measuring uncertainty, a mathematical model was established. The components of uncertainty and their sources were analyzed. The uncertainty of each component was calculated. Finally, the combined standard uncertainty And expand the uncertainty. The result of extended uncertainty is 0.10%, K = 2. Conclusion The relative standard uncertainty of standard solution and the uncertainty of titration with zinc sulfate solution are the main factors that determine the content of calcium dihydrogen phosphate in food additive by zinc sulfate back titration.