尿中碘的过硫酸铵消化—砷铈催化分光光度测定方法

Method for measuring iodine in urine by As3+-Ce4+ catalytic spectrophotometry using ammonium persulfate digestion

目的介绍修订后的尿碘测定标准新方法,即尿中碘的过硫酸铵消化-砷铈(As3+、Ce4+)催化分光光度测定方法,建议各级实验室应尽快应用.方法按'研制生物样品监测检验方法指南'(WS/T 68-1996)的规定,对我国现行的尿碘测定方法标准进行了修订,并对修订后的新方法进行方法学评价.结果修订后的新方法尿碘检测范围为0～300μg/L;最低检测量为3μg/L(取样量为0.25 ml);精密度:测定尿碘为63.3、129.8、252.5μg/L时,变异系数(CV)分别为5.5%、2.8%、4.4%(n=6);准确度:对低、中、高碘3种尿样加碘标平均回收率分别为101.3%、97.6%、95.8%(n=6),总平均回收率为98.3%(范围:92.6%～107.0%);测定低、高2种尿碘标准物,其结果与给定值的相对偏差分别为4.9%和1.0%(n=6);该方法的砷铈反应除了在水浴控温条件下进行,还可以直接在20～35℃之间某一稳定的室温条件下进行测定.结论修订后的新方法比原标准方法更加简便易操作,并提高了测定的精密度和准确度.

Objective To introduce a new method for determination of urinary iodine by using ammonium persulfate digestion, this method was modified from the national standard method of chloric acid digestion. Methods The modification for the national standard method was conducted and the methodological assessment for the modified method was worked out according to the 'guide for methods of monitoring biological materials'. Results The calibration range of the new method was 0 - 300 μg/L and the lowest limit of detection was 3μg/L or 0.75 ng (0.25 ml of urine was tested). The test variations (CV) were 5.5%, 2.8% and 4.4% when measuring urine samples with iodine concentration of 63.3 μg/L, 129.8μg/L and 252.5μg/L, respectively. The average recovery was 98.3% with a range of 92.6%-107.0% when measuring urine samples containing different iodine concentration. The test results of 'Standard material' were all within the given range and the relevant deviation (RD) was 4.9% and 1.0%, respectively. This method can be performed not only in the controlled temperature (using water bath), but also in a certain stable room temperature between 20-35℃. Conclusions This new modified method is easier to be performed with better precision and accuracy, and this method is suitable to almost routine laboratories for measuring iodine in urine.