Chemical speciation of L-glutamine complexes with Co(II), Ni(II) and Cu(II) in cationic micellar medium

The impact of cationic micelles on the protonation equilibria of L-glutamine and chemical speciation of its complexes with Co(II), Ni(II) and Cu(II) have been studied by monitoring hydrogen ion concentration pH metrically at 303 K and at an ionic strength of 0.16 M. The protonation constants and binary stability constants have been calculated with the computer program MINIQUAD75. The best fit chemical models are selected based on standard deviations in the model parameters and residual analysis using crystallographic R-factor and sum of squares of residuals in all mass-balance equations. The trend in the variation of stability constants of the complexes with mole fraction of the surfactant is attributed to the compartmentalization of complexation equilibria. Distribution of species and effect of influential parameters on chemical speciation have also been presented. KEY WORDS: Chemical speciation, complex equilibria, L-glutamine, cationic micelles Bull. Chem. Soc. Ethiop. 2012, 26(3), 383-394. DOI: http://dx.doi.org/10.4314/bcse.v26i3.7