Soft‐modeling based spectrofluorimetric study of simultaneous equilibria

Abstract

A two-way soft resolution method will fail when applied to a simultaneous equilibria system due to rank deficiency in its concentration profiles. Increasing the dimensionality of measurements from two-way to three-way data can be used to overcome this problem. Simultaneous dissociation of two weak acids is considered as a model for simultaneous equilibria. Three-way data obtained from excitation-emission spectrofluorimetric monitoring of a pH-metric titration is analyzed using a proper combination of well-known soft-modeling methods. Multivariate curve resolution-alternating least squares is used for calculating the excitation and emission spectral profiles of involved species and rank annihilation factor analysis for obtaining the contribution of each species in measured excitation-emission matrices at different pHs. The results of simulated and real simultaneous acids dissociation equilibria showed that the proposed combined method performs well even in situation when the equilibrium constants are close to each other. The applicability of method for study of an acidic dissociation is also shown.

A perspective on the growth of chemometrics in Iran: a glance into activities between 2005 and 2012

“…They published these two works in one of the top chemistry journals, Analytical Chemistry [3,4]. The research group of Abdollahi has developed different factor analysis-based curve resolution methods to resolve different chemical systems [27][28][29][30][31]. Tautomerization equilibria in aqueous micellar solutions and acid dissociation equilibria in mixed solvent media were studied using factor analysis methods by this group [27,29,32].…”

“…Tautomerization equilibria in aqueous micellar solutions and acid dissociation equilibria in mixed solvent media were studied using factor analysis methods by this group . They also studied multicomponent simultaneous equilibria using self‐modeling methods . Maximum likelihood principal component analysis was used as the initial projection step in the MCR analysis of noisy data by this group .…”