摘要目的 建立根据反应速率测定尿碘的方法(速率法),扩大尿碘测定的线性范围.方法 对消化处理后的尿样和标准系列,进行砷铈催化反应测定.利用分光光度计的动力学测定功能(测定波长420 nm),记录每一个测定体系中吸光值(A)随时间(t)变化的曲线∽-t曲线),在此曲线上选择(A1,t1)和(A2,t2)点,计算反应速率(v),v=(lgA1-lgA2)/(t2-t1),以1 000(v-vo)为X(vo为试剂空白的反应速率),通过标准系列的测定,计算碘的含量(C)与X的回归方程:C=a±bX.计算样品的X值,并将其代入回归方程求得尿样中的碘含量.结果 ①C与X呈正相关,标准系列线性范围为0 ～1 200 μμg/L,相关系数r＞0.999 1;最低检出限为3.9tμg/L(取0.25 ml尿样).②精密度:在0～1 200 μg/L范围内选择A、B、C、D、E5份尿样,精密度试验测得值为(72.3±2.7)、(148.2±5.2)、(210.5±4.4)、(562.7±6.8)、(899.3±8.0)μg/L,相对标准偏差(RSD)在0.9％ ～ 3.8％.③准确度:对A、B、C、D4份样品做加标回收试验,回收率在94.2％ ～ 107.2％;测定给定值分别为(67.9±9.0)、(142.0±1o.0)、(195.0±10.0)、(558.0±17.0)、(885.0±28.0) μg/L的国家尿碘标准物质,结果均在标准物质的不确定范围之内.④方法对比试验:对用国家卫生标准《尿中碘的砷铈催化分光光度测定方法》(WS/T 107-2006,标准方法)测定结果为0 ～ 300 μg/L和＞300 μg/L的尿样各60份,同时用速率法测定.0～300 μg/L的60份样品,两种方法测定结果呈正相关(r=0.994,P＜ 0.01),速率法测定结果平均值略低于标准方法,差异有统计学意义(t=2.047,P＜0.05),但平均偏差仅为2.1 μg/L,对尿碘测定来说没有实际意义;＞300 μg/L的60份尿样,两种方法测定结果呈正相关(r=0.993,P＜ 0.01),差异无统计学意义(t=-1.092,P＞0.05).结论 砷铈催化速率法测定尿碘,扩大了尿碘测定的线性范围,绝大多数样品直接取样,不需稀释,可以减少尿碘测定的工作量.

abstractsObjective To establish a arsenic cerium catalytic rate method for determination of urinary iodine,and increase the linear range of urinary iodine determination.Methods Standard series and urine samples after digestion treatment,were tested using dynamics function of spectrophotometer to record the curve of absorbance value (A) change with time (t) during arsenic cerium catalytic reaction for each measurement system,choice (A1,t1) and (A 2,t2) on this curve and calculating the reaction rate (v),v =(lgA1-lgA2)/(t2-t1).Through the determination of the standard series it could calculate regression equation of iodine concentration (C) with X:C =a ± bX,X =1 000 (v-v0),and the v0 is the reaction rate of reagent blank.Results (① C and X were positively correlated.The standard series linear range was 0-1 200 pμg/L and correlation coefficient r was higher than 0.999 1.The minimum detection limit was 3.9 μg/L (0.25 ml urine).②)Precision:5 urine samples (A,B,C,D,E) were selected within the range of 0-1 200 μg/L and the measured value were (72.3 ± 2.7),(148.2 ± 5.2),(210.5 ± 4.4),(562.7 ± 6.8),and (899.3 ± 8.0) μg/L.The relative standard deviation (RSD) was between 0.9％-3.8％.(③)Accuracy:4 samples (A,B,C,D) were measured for standard addition recovery test,recovery was between 94.2％-107.2％;urinary iodine standard material [the given values were (67.9 ± 9.0),(142.0 ± 10.0),(195.0 ± 10.0),(558.0 ± 17.0),(885.0 ± 28.0) μg/L] were determined and the results were in the range of uncertainty of the standard material.④Method contrast:with the national health standard method (method for determination of iodine in urine by arsenic cerium catalytic spectrophotometry) to determinate 120 urine samples,the results showed that there were 60 urine samples within 0-300 μg/L,60 urine samples were more than 300 μg/L.Then rate method was used to test the 120 urine samples.For the 60 samples within the scope of 0-300 μg/L,the determination results of the two methods were positively correlated (r =0.994,P ＜ 0.01);the results of the rate method were lower than those of the standard method and the difference was statistically significant (t =2.047,P ＜ 0.05).But the average deviation was only 2.1 μg/L,for the determination of urine iodine there was no practical significance;for the 60 samples higher than 300 μg/L,the determination results of the two methods were positively correlated (r =0.993,P ＜ 0.01) and the difference was not statistically significant (t =-1.092,P ＞ 0.05).Conclusions Arsenic cerium catalytic rate method has increased the linear range of urinary iodine determination.Using this method,the vast majority samples can be tested directly without dilution,thereby reducing the workload for determination of urine iodine.