Rapid determinations of complexing stability constants by gradient flow-injection titration

The use of rapid gradient flow-injection titration for the determination of equilibrium constants in solution, previously used in pK measurements of monobasic and multibasic weak acids is extended to the more demanding case of metal complexation. Formation constants for the complexes ML and ML2 of Cd2+ with glycine have been determined by that technique using potentiometric detection with a glass electrode. Under optimum conditions formation constants in good agreement with batch and literature values are obtained in several minutes.