Multivariate curve resolution of voltammetric data for Ni-tartarate complexation system with both labile and inert behaviour

Abstract

The complexation between Ni²⁺ and tartarate, in TRIS buffer, which forms successive complexes, was studied by differential pulse polarography (DPP) and multivariate cure resolution (MCR). This system shows both electrochemically inert and labile attribute. It is very difficult, if not impossible, to analyze such systems by conventional and classical methods. Experimental data were obtained by DPP for different metal-to-ligand ratio at pH = 7.5. This procedure was done by adding appropriate volume of tartarate solution to a metal ion solution with constant concentration of Ni²⁺. The complex formation constants obtained by resolving the data matrix by soft modeling approach and those obtained by conventional method were compared, and there was no significant difference between them. Although the condition of linearity of the current data with respect to the concentrations is not totally fulfilled, but the results show the variation from linearity for the studied system is small and can be neglected. Thus, the MCR provided good estimations for the stability constants of complexation process, and is suitable for use as a complementary tool on the study of systems with both successive inert and labile complexes.