Thermodynamic considerations in co-ordination. Part XVIII. Formation constants for cadmium(II)–amino-acid complexes as determined by glass and solid-state cadmium-electrode potentiometry

Abstract

Potentiometrically determined formation constants are reported for the cadmium(II)–asparaginate,–aspartate,–cysteinate,– glutaminate,–histidinate,–phenylalanate,–serinate, and –tryptophanate systems at 25 °C and I= 3·00M(Na)ClO₄. Computer-simulated models of blood-plasma conditions have been used to examine (a) complexing competition between cadmium(II) and manganese(II)–,iron(II)–,cobalt(II)–,copper(II)–, and zinc(II)–amino-acid anion complexes, and (b) to assess selectivities of ethylenediaminetetra-acetic acid (H₄edta) for cadmium(II) and the in vivo essential amino-acids and metal ions listed. Criteria for producing a drug more specific than those currently in use are discussed.