Simple open fusion for an iodine screen test.

SEVERAL TESTS have been proposed for determining the gross contamination sometimes encountered in serums submitted for protein-bound iodine analysis (1-5). These screens are all l)ased on the use of the coupled Ce(IV-As(III)) reaction as a detection device. However, ceric ions in strong acid solution represent a powerful oxidation system for many organic compounds (6). There is, therefore, a good possibility that these compounds are capable of reducing Ce(IV) to give the appearance of the presence of iodine. It is impossible to differentiate simple Ce(IV) reduction from the iodine catalyzed Ce(IV) and As (III) reaction by measurement of loss of Ce(IV) color alone. Our own experiences with several of these preliminary semiquantitative contamination-exclusion tests has indicated that too many samples were eliminated which subsequent analysis showed to be uncontaminated. We attempted to develop a simple procedure which would yield a reliable screen test with an open-alkaline-combustion technic employing ordinary burners and porcelain crucibles. This extremely rapid process could be used to destroy the organic precipitate containing the iodine without apparent loss of the latter in the conversion to high melting potassium iodide. An important feature of such a system would be the ability to screen large numbers of samples without cross