尿碘测定低砷量改进标准方法的精密度和准确度观察

Precision and Accuracy of Modified Method(Low Arsenic) for Urinary Lodine Determination

目的观察拟修订的尿碘测定标准方法（简称低砷改进法）的精密度和准确度。方法按WBZ／T210．5—2008《生物材料中化学物质测定方法》的规定，对低砷改进法（检测范围0～300μg／L）精密度和准确度进行方法学评价。结果低砷改进法的碘浓度与相应吸光度对数值呈线性相关（r〉0．9990）；测定尿样碘含量为36．4、152．0、254．5μg／L时的变异系数（CV）分别为3．6％，2-4％，1．7％；测定低、高两种碘浓度的国家尿碘标准物，其结果与给定值的相对偏差分别为-1．4％和0．5％；测定低、中、高3种不同碘含量的尿样加碘标回收率分别为101．7％，97．1％，100．8％，平均回收率为99．9％，回收率范围为94．1％-105．7％。低砷改进法的砷铈反应速度缓慢，在测定50、150、250μg／L碘浓度时，现行标准方法吸光度值的变化速率分别是改进方法的1．48、1．24、1．21倍。结论该法在尿碘4-300μg／L检测范围时具有良好的精密度和准确度，不仅减少环境砷污染，更易于操作，推荐应用。

Objectlve To konw the precision and accuracy of the modified method （low arsenic） for the determination of iodine in urine. Methods The methodological assessment for the precision and accuracy of the modified method （0-300 g/L calibration range） of low arsenic was worked out according to WSfF68--1996 the Guide for Method of Monitoring Biological Materials. Results The linear correlative coefficient of modified method of low arsenic was above 0.999 0 and the coefficients of variation （CVs） were 6.0%, 2.4% and 1.7% （n=6） when testing urinary iodine at 36.8 g/L, 152.0 g/L and 254.5 g/L, respectively. The test results of two standard materials were all within the given range and the relevant deviations （RDs） were -1.4% and 0.5%（n=6）, respectively. The average recovery was 99.9% in a range of 94.1%-105.7%, when measuring different urine samples with quantitative iodine added. The speed of arsenic-cerium reaction was observed by testing the change of absorbency （AA /minute）, and the results showed that the original method had a 1.48, 1.24 and 1.21 times as faster as the modified method on measuring iodine at 50, 150 and 250 μg/L, respectively. Conclusion This modified method of low arsenic （4-300 g/L calibration range） can not only reduce environmental arsenic pollution, but be easier to be performed with better precision and accuracy, and should be recommended to apply in the determination of iodine in urine.