The complexometric titration of micro and ultramicro quantities of calcium in blood serum, urine, and inorganic salt solutions.

EVER SINCE THE CLASSIC OXALATE METHOD of Kramer and Tisdall (1), for the determination of serum calcium, simpler methods have been sought to determine calcium. Among the more important methods suggested have been flame photometry, colorimetry, and titrimetry. Flame photometry of calcium in serum and urine has not as yet been satisfactorily developed. Serious and rather unpredictable interferences from other ions present, necessitate more elaborate equipment (2, 3). Although several colorimetric procedures have been proposed (4-6), none of these methods, to our knowledge, have been used routinely in this country. A promising method has been published by Kingsley and Robnett (7). New titrimetric procedures have been reported. These procedures are based on Schwarzenbach’s (8, 9) complexometric titration of metallic ions with disodium ethylenediaminetetraacetate (EDTA),