Ultramicrodetermination of Iodine by a Rapid Automatic Reaction-Rate Method.

Abstract

An automatic spectrophotometric reaction rate method for the ultramicrodetermination of iodide is based on the Sandell-Kolthoff reaction, in which a trace of iodine or iodide acts as catalyst for the reduction of Ce(IV) in the presence of As(1H). The time required for the reaction to consume a small fixed amount of ceric ions, and therefore for the absorbance to decrease by a preselected amount (about 0.06 unit), is measured automatically and related directly to the iodide concentration. Ultramicro amounts of iodide in the range of 0.015 to 0.45 mu g were determined with relative errors of about 1 to 2% and measurement times of only about 10 to l00 seconds. The method should be adaptable for the determination of protein-bound iodine (PBI). (auth)