Simple determination of iodine in small specimens of thyroid tissue

This work describes a simple photometric determination of the iodine concentration in thyroid tissue, a method based on the well-known catalytic Sandell-Kolthoff reaction. The modified ceric arsenite reaction is very sensitive and does not require complicated laboratory equipment. It can be performed in any routine clinical laboratory if instructions are followed strictly. By means of this method iodine concentration can be determined even in small specimens, for instance puncture samples of thyroid tissue or thyroid glands of small animals (mouse). Previous to the analysis, the tissue is digested in a mixture of sodium chlorate and perchloric acid at 100 degrees C. Using this manner of digestion between 94 and 110% of iodine in the sample were recovered. Comparison with neutron activation analysis showed excellent agreement of the obtained values.