THE DETERMINATION OF PROTEIN-BOUND IODINE BY DRY ASHING

Abstract

THE relation of thyroid function to circulating iodine in the human appears to be well established (1–6) but the technical difficulties inherent in the determination of amounts of iodine of the order of 0.02 gamma have discouraged the universal adoption of existing methods (7, 8) as routine diagnostic aids. The methods most commonly used are based on Chaney's (9) procedure and involve acid digestion of the washed serum protein, reduction, distillation and absorption of the evolved iodine, and finally its colorimetric determination by its catalytic effect on the reduction of eerie sulfate by arsenious acid. To eliminate the constant attention required in the acid digestion procedures, Barker has recently introduced (10) an alkaline ashing method with subsequent acid leaching of the iodine from the ash. Considerable simplification is thereby attained, since no attention is required during the two to three-hour incineration period.