Acid digestion determination of iodine in foods.

A method for determining iodine in food is described. The samples were digested using a mixture of sulfuric, nitric, and perchloric acids. The iodine was determined by an automated colorimetric method based on the iodide-catalyzed reduction of Ce+4 by As+3. For milk samples, the relative standard deviation for the method was less than 3%, and the recovery of 125I added to milk and carried through the method ranged from 96 to 102%. The method was compared with 4 other procedures and was superior to alkaline dry ashing methods.