Two colorimetric assays for iodine in foods

Using a standardized sample preparation, comparisons were made of two colorimetric iodine assays that are based on different chemistry. One assay kinetically measured the initial iodine catalysis of the redox reaction between Ce+4 and As+3 other monitored iodine catalysis of the reaction between thiocyanate and nitrite by measuring light absorbance after 20 min. Both were accurate when tested with reference samples of nonfat milk powder and oyster tissue that had known certified iodine content. The thiocyanate-nitrite assay consistently showed greater precision and less variability, particularly at lower iodine concentrations in lyophilized egg samples