EQUILIBRIUM STUDIES OF ASPARTAME AND SOME OF ITS DEGRADATION PRODUCTS WITH HYDROGEN(I) AND COPPER(II) UNDER PHYSIOLOGICAL CONDITIONS USING POTENTIOMETRIC PH MEASUREMENTS

摘要

Equilibrium studies of N-L-alpha-aspartyl-L-phenylalanine 1-methyl ester (aspartame) and some of its degradation products (L-phenylalanine, L-aspartic acid) with hydrogen(I) and copper(II) were carried out under physiological conditions (I = 0.15 M (NaCl) in water, 37 degrees C) using potentiometric titrations. The concentration stability constants of binary and ternary complexes of copper( II) with aspartame, L-phenylalanine and L-aspartic acid, as well as those of the binary complexes of nickel(II) and aspartame, are reported. Quatemary solutions containing the three ligands and copper(II) were measured and the pH values obtained are compared with those obtained using a simulated model. [References: 30]