Semi-automatic method for the determination of total iodine in food

Abstract

A simple method for the determination of total iodine in food, based on the catalytic destruction of thiocyanate by nitrite in the presence of iodide, has been evaluated and the colorimetric finish technique automated. Optimum conditions for the destruction of organic matter and the liberation of iodine have been investigated and a set of conditions applicable to the automated finish technique developed. The method, when applied to 160 foods, had a precision of about 10%, a detection limit for iodine of 1 µg per 100 g of food, a mean recovery of added iodide of 90% and an output of about 70 samples per week. The effect of storage conditions on the iodine content of fish and eggs has also been examined, and the effect of some possible interfering substances, such as chloride, bromide and mercury, investigated.