碘元素自动检测仪测定水碘的方法学评价

Methodological evaluation of an automatic iodine element detector for measuring water iodine

目的评价碘元素自动检测仪测定水碘方法的可行性。方法应用碘元素自动检测仪测定水碘浓度,同时对该方法进行方法学特性试验,包括标准曲线线性关系,精密度实验,加标回收实验,水碘标准物质GBW09113j、GBW09114j,并与砷铈催化分光光度法进行方法比对实验。结果采用碘元素自动检测仪进行测定,在碘浓度2、10、20、40、60、80、100、120μg/L标准曲线范围内,6次平行测定相关系数(r)范围为-0.9999~-0.9996。精密度分析显示,平行测定低、中、高碘浓度水样各6次,对应的变异系数(CV)分别为2.2%、3.0%、3.2%,均<5%。加标回收实验显示,低、中、高碘浓度水样2次加碘标后,回收率分别为97.0%、98.8%、99.5%,总平均回收率为98.4%。2种水碘标准物质的测定结果均在给定的标准值±不确定度范围内[(8.2±1.2)、(61.0±6.0)μg/L]。分别应用碘元素自动检测仪与砷铈催化分光光度法测定30份水样,结果比较差异无统计学意义(t=-1.62,P=0.116)。结论碘元素自动检测仪测定水碘,虽存在标准曲线线性范围未覆盖0~<2μg/L的不足,但其自动化程度高,精密度高、准确度好,与砷铈催化分光光度法结果比对一致性良好,在水碘测定上具有很好的应用前景。

Objective To evaluate the feasibility of using an automatic iodine element detector to detect water iodine.Methods Water iodine was determined by an automatic iodine element detector.The methodological characteristics of this method was tested,including linear relationship of standard curves,precision tests,standard recovery experiment,and certified reference material GBW09113j,GBW09114j determination experiments.The methodological comparison experiment was conducted using arsenic cerium catalytic spectrophotometry.Results Using an automatic iodine detector,in the range of 2,10,20,40,60,80,100,and 120μg/L standard curve,the correlation coefficient(r)for six parallel measurements ranged from-0.9999 to-0.9996.Precision analysis showed that the low,medium,and high iodine concentration water samples were measured six times in parallel,with corresponding coefficient of variation(CV)of 2.2%,3.0%,and 3.2%,all of which were less than 5%.The standard recovery experiment showed that the recovery rates of low,medium,and high iodine concentration water samples after two rounds of standard were 97.0%,98.8%,and 99.5%,respectively,with a total average recovery rate of 98.4%.The detection results of the two reference materials were within the range of the given standard given by the national standard values[(8.2±1.2),(61.0±6.0)μg/L].The iodine content of 30 water samples was determined by the automatic iodine detector and the arsenic cerium catalytic spectrophotometry,and the results showed no statistically significant significance(t=-1.62,P=0.116).Conclusions Although the concentration range of standard curve does not cover 0-<2μg/L,the determination of water iodine by automatic iodine detector has advantages of high automation,high precision,good accuracy,and the results are in good agreement with the results of arsenic cerium catalytic spectrophotometry.It has good application prospects in water iodine determination.