Heckman M M
J Assoc Off Anal Chem. 1979 Sep;62(5):1045-9.
An accurate, reproducible method for less than or equal to 1 ppm iodine in foods is required for nutritional labeling. In order to ascertain the current status of iodine analysis in foods, 7 samples, representing different food classes, were analyzed by 8 laboratories. Six laboratories used their modifications of the Ce-As-I catalytic method preceded by alkaline dry ashing. Two laboratories used neutron activation analysis (NAA), with differing radiochemical separations. The study showed wide discrepancy in analytical results. Mean relative standard deviation for all laboratories was 77.9% between laboratories; 19.1% within-laboratories. Laboratories using NAA had only slightly better precision than did laboratories using the chemical method. The lowest level reported on the entire group of samples ranged among laboratories from 0.0089 to 0.65 ppm. Figures reported by a laboratory are, in general, consistently high or consistently low. The only differences in methodology which may possibly correlate with level of iodine obtained are the use of NAA technique and use of manual, rather than automated, colorimetry.
营养标签需要一种准确、可重复的方法来测定食品中碘含量小于或等于1 ppm的情况。为了确定食品中碘分析的现状，8个实验室对代表不同食品类别的7个样品进行了分析。6个实验室使用了在碱性干灰化之前的铈 - 砷 - 碘催化法的改进方法。2个实验室使用了中子活化分析（NAA），放射化学分离方法不同。研究表明分析结果存在很大差异。所有实验室之间的平均相对标准偏差为77.9%；实验室内部为19.1%。使用NAA的实验室的精密度仅略优于使用化学方法的实验室。整个样品组中报告的最低水平在各实验室之间为0.0089至0.65 ppm。一个实验室报告的数据通常要么一直偏高，要么一直偏低。可能与所获得的碘含量水平相关的方法学上的唯一差异是NAA技术的使用以及使用手动比色法而非自动比色法。
