Original scientific paper

The Use of Graph-theoretical Models to Evaluate Two Electroanalytical Methods for Determination of Stability Constants

Nenad Raos ; Institute for Medical Research and Occupational Health, Zagreb, Croatia
Gina Branica ; Institute for Medical Research and Occupational Health, Zagreb, Croatia
Ante Miličević orcid.org/0000-0003-1536-6278 ; Institute for Medical Research and Occupational Health, Zagreb, Croatia

Abstract

Stability constants K1 and b2 of copper(II) complexes with alanine and its five N-alkylated and
N,N-dialkylated derivatives were measured by glass electrode potentiometry (GEP) and square
wave voltammetry (SWV) and evaluated using graph-theoretical models. Correlations with the
connectivity index of the 3rd order, 3cv, show that log K1(GEP) values were better reproduced
than log K1(SWV) values; S.E. = 0.18–0.16 vs. 0.29–0.35, respectively. The opposite is true for
log b2 (S.E. = 0.51–0.56 vs. 0.39–0.47 for GEP and SWV, respectively). By applying three criteria
– 1) difference between GEP and SWV values, 2) difference between SWV and theoretical
values, and 3) correlation of experimental error (S.E.exp) to the difference between experimental
and theoretical values – it was possible to determine three experimental log K1(SWV)
values as problematic. This report demonstrates the value of recently developed graph-theoretical
models in planning the experiments and discussing their results.

Keywords

glass electrode potentiometry (GEP); square wave voltammetry (SWV); copper(II) chelates; amino acid; stability constant; topological indices

Hrčak ID:

31139

URI

https://hrcak.srce.hr/31139

Publication date:

15.11.2008.

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