Calcium determination in biologic material.

THE CLASSICAL PROCEDURE for the determination of calcium in biologic fluids involves the precipitation of calcium as the oxalate and titration of the oxalate with potassium permanganate. The permanganate titration has certain difficulties. The oxalate solution has to be heated during the titration (1) and the end point is unreliable in dilute solutions (2). The use of cerate oxidimetry avoids these circumstances. The principles of cerate oxidimetry have been well established in the chemical literature and there have been numerous applications to the determination of calcium (2-8). The present report defines conditions which proved to be most satisfactory for the determination of calcium in biologic material. The method has proved reliable through several years of use since 1940 in this and other laboratories. The accuracy is ±2 per cent as measured by the recovery of known amounts of calcium.