Spectrophotometric titration of calcium and magnesium with complexon-III and metal-specific indicators

The equivalence points of the Ca and Mg titrations with complexon-III, using metal-specific indicators, can be determined more accurately by the spectrophotometric than by the visual method. In comparison with the spectrophotometric method in the ultraviolet⁷, where no indicator is required, the end point can be determined more sharply from our titration curve.The accuracy is of the order of 0.5% ; the repeatibility is even more favourable.