Rapid test for detection of certain iodinecontaining contaminants in serum.

T HAS BEEN OUR EXPERIENCE (1) that accurate measurement on large numbers of samples in a minimum amount of working time per specimen can be achieved consistently in the analysis of protein-bound iodine by means of alkaline incineration. However, with the use of incineration, where many samples may be exposed simultaneously in enclosed spaces such as centrifuges, drying ovens, and muffle furnaces, it is essential not to include specimens of high iodine content (500 g. per 100 ml., or higher). Sera from patients who have received iodinated compounds such as iodinated radiopaque media for roentographic purposes may, while under test, release relatively large amounts of iodine. Some of the released iodine may be absorbed by the other samples in sufficient quantity to invalidate the entire series of tests. This phenomenon, and a method for screening out sera containing high concentrations of iodine, was first described by Samson et a!. (2). Malkin (3) introduced a modification, which eliminated the use of a muffle furnace, and at the same time, precluded the possibility of interferences occurring during the steps prior to incineration. The modification described here is rapid, and can easily be performed in a laboratory devoted to determinations of protein-bound iodine. Briefly, unknowns with sodium carbonate are heated in an oven, resulting in the release of iodine from potential contaminators in concentrations of sufficient magnitude for detection by means of the sulfate-ceric acid catalysis in conjunction with brucine sulfate. The entire procedure can be completed in approximately twenty minutes