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

Equilibrium studies of N-L-alpha-aspartyl-L-phenylalanine 1-methyl est er (aspartame) and some of its degradation products (L-phenylalanine, L-aspartic acid) with hydrogen(I) and copper(II) were carried out unde r 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-phen ylalanine and L-aspartic acid, as well as those of the binary complexe s of nickel(II) and aspartame, are reported. Quatemary solutions conta ining the three ligands and copper(II) were measured and the pH values obtained are compared with those obtained using a simulated model.