Sub-stoichiometric isotope dilution analysis method for the determination of iodine in common salts using iodine-131 tracer

A sub-stoichiometric isotope dilution analysis (SIDA) method was developed for the determination of iodine in different brands of common salts. An aqueous salt solution containing 131I tracer and NaI as carrier is oxidized by tartaric acid and KIO3 and the liberated iodine is extracted with CCl4. To the extract an aqueous solution of AgNO3 is added in substoichiometric amount to obtain a colloidal solution of AgI. On adding sodium thiosulfate solution, the NaI so formed passes into aqueous solution, which is then counted. Several different brands of salt were analysed. The method is especially suitable for the determination of microgram amounts of iodide in the presence of excess of chloride. (Author)