A Micro Colorimetric Method for the Quan- Titative Estimation of Iodine in Blood

Various investigators have reported on methods for the estimation of iodine in air, food, water, vegetables, tissue, and blood. Chatin (1) in 1851 used the method of Rabourdin (2) and established the presence of iodine in air. Rabourdin’s method depends on converting the iodine to potassium iodide, setting it free with nitrous acid, and extracting with carbon disulfide. Detection was possible in solutions containing 1 part per million of iodine. A year later Grange (3) showed that the starch-iodide reaction could be used in solutions containing 5 parts per million; this later became the basis for the titration method. In 1913 Blum and Griitzner (4) contributed a method for the estimation of iodine in blood. The principle involved combustion of the organic matter by their barium superoxide method, oxidation of iodide to iodate by permanganate, and titration with 0.01 N thiosulfate. The determination required 200 cc. of blood. Kendall and Richardson (5) in 1920 developed a similar method for the detection of iodine in blood and animal tissue. They oxidized iodide to iodate quantitatively by the action of bromine or chlorine. The iodine is liberated by an excess of potassium iodide. This reaction produces 6 times the amount of iodine originally present. The liberated iodine was then titrated with 0.005 N thiosulfate. The average iodine content of human blood.was found to be 0.013 mg. per 100 cc. 100 cc. of blood were required for determination. Stieglitz (6) in 1923 precipitated iodine as palladous iodide (PdI2) and used this reaction for microchemical detection of iodine in tissues.