应用全自动碘分析仪测定鲜奶及奶粉中碘含量的方法学评价

Methodological evaluation of iodine content in fresh milk and milk powder using automatic iodine analyzer

目的建立全自动碘分析仪测定鲜奶及奶粉中碘含量的分析方法。方法用碱灰化处理样品后,应用全自动碘分析仪测定鲜奶及奶粉内碘离子含量,进行方法学评价。结果该方法检测范围为0~500μg/L碘,标准曲线的平均相关系数为0.9999,检测限为5μg/kg,样品加标回收率为96.0%~101.8%,精密度(RSD,n=6)为1.55%~3.04%。全自动碘分析仪法和砷铈催化分光光度法对低、中、高3种浓度样品的碘含量检测的结果差异无统计学意义(t=0.424、0.607、0.073,P均>0.05)。两种方法对低(t=0.902,P=0.388)、中(t=0.318,P=0.757)、高(t=1.783,P=0.105)浓度样品加标后的碘含量检测的结果差异无统计学意义。两种方法测定30份鲜奶及奶制品中碘含量检测的结果差异无统计学意义(t=0.396,P>0.05)。结论应用全自动碘分析仪测定鲜奶及奶粉中碘的精密度、准确度均可达到标准方法水平,样品试剂用量少、程序简单、操作容易,适用于鲜奶及奶粉中总碘的检测。

Objective To establish an analysis method for the determination of iodine content in fresh milk and milk powder by automatic iodine analyzer.Methods After treating the sample with alkali ashing,the iodine ion contents in fresh milk and milk powder were determined by an automatic iodine analyzer and the methodological evaluation was carried out.Results The detection range of this method was 0-500 μg/L iodine,the average correlation coefficient of the standard curve was 0.999 9,the detection limit was 5 μg/kg,the recovery rate of sample spike was 96.0%-101.8%,and the precision(RSD,n=6) was 1.55%-3.04%.Arsenic-cerium catalyzed spectrophotometry and fully automated iodine analyzer were compared for low(t= 0.424,P = 0.681),medium(t= 0.607,P = 0.557),and high(t= 0.073,P = 0.943),and there was no significant difference between the two methods in the results of iodine content detection among the three concentrations.There was no significant difference in iodine content detection between the two methods after spiked with low(t = 0.902,P = 0.388),medium(t = 0.318,P = 0.757),and high(t = 1.783,P = 0.105) concentrations.There was no significant difference between the two methods in the determination of iodine content in 30 samples of fresh milk and dairy products(t = 0.396,P > 0.05).Conclusions The precision and accuracy of the determination of iodine in fresh milk and milk powder by automatic iodine analyzer are no different from the standard method.The amount of sample reagents is small,the procedure is simple and the operation is easy,which is suitable for the detection of total iodine in fresh milk and milk powder.