Gas chromatographic determination of total iodine in foods.

A gas chromatographic (GC) method has been developed for determination of total iodine in foods, based on the reaction of iodine with 3-pentanone. Organic matter of a sample is destroyed by an alkaline ashing technique. Iodide in a water extract of the ash residues is oxidized to free iodine by adding dichromate in the presence of sulfuric acid. Liberated iodine is reacted with 3-pentanone to form 2-iodo-3-pentanone, extracted into n-hexane, and then determined by gas chromatography with an electron-capture detector. Recoveries of iodide from spiked food samples ranged from 91.4 to 99.6%. Detection limit for iodine is 0.05 micrograms/g.