A modification of current micro-methods for the estimation of diodone (3:5-di-iodopyridone-N-acetic acid).

The investigation of renal function in health or disease demands a reliable method for the estimation of diodone in blood and urine. The methods of Alpert (1941), Flox, Pitesky & Alving (1942), Corcoran & Page (1943) all involve the use of bromine to split iodine from the diodone molecule and to convert this into iodate. Having had a fairly wide experience in the use of diodone in the estimation of renal blood flow and tubular mass in normal men and patients, as well as in animals, we have reexamined the various methods, and now present a procedure which, by a suitable combination of the best features of the other methods, combines accuracy with speed. By this method it is possible to perform the analysis of the blood and urine samples from a clearance test in about 30 min., whereas Alpert's method takes the greater part of a day. In the procedure here presented the diodone iodine is converted by a bromide-bromate mixture into iodate; the excess Br2 removed by sodium formate and the iodate estimated colorimetrically by-acidification and the addition of excess KI.