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目的:通过直接滴定法对碘盐中碘离子含量测定不确定度的研究,为碘盐中碘离子含量测定的质量控制提供依据。方法:采用GB/T13025.7-1999《制盐工业通用实验方法-碘离子的测定方法》测定碘盐碘离子含量以及均值、标准差、方和根等统计学方法。结果:经过计算碘盐碘离子含量测量不确定度各分量值,得到U(ω)相对标准不确定度为0.0023,U(m)1/万和U(m1)1/千天平的最大允许误差导致的样品质量不确定度分别为0.00020和0.00029,U(v校)容量瓶定容体积引入的不确定度为0.00056,U(v校1)滴定管滴定引入的不确定度为0.00075;最终合成不确定度为0.0023。结论:影响碘盐碘离子测定不确定度的最主要因素是U(ω),即样品测量滴定消耗标准滴定液的体积。
OBJECTIVE: To study the uncertainty of determination of iodine ion in iodized salt by direct titration, and to provide the basis for the quality control of iodine ion in iodized salt. Methods: The method of GB / T13025.7-1999 “General method of salt industry - Determination of iodine ion” was used to determine iodine ion content, mean value, standard deviation, square root and other statistical methods. Results: The maximum allowable errors of U (ω) relative standard uncertainty of 0.0023, U (m) 1/10000 and U (m1) 1 / The uncertainty of the sample quality caused by U (v) was 0.00020 and 0.00029 respectively. The uncertainty introduced by the U (v) calibration volumetric flask volumetric injection was 0.00056. The uncertainty introduced by U (v 1) burette titration was 0.00075. The degree of certainty is 0.0023. Conclusion: The most important factor influencing the uncertainty of determination of iodide salt iodide ion is U (ω), that is, the volume of standard titration solution consumed by titration of sample.