Selectivity of single, mixed, and modified pseudostationary phases in electrokinetic chromatography

Abstract

The selectivity of a compilation of single, mixed, and modified EKC pseudostationary phases, described in the literature and characterized through the solvation parameter model, is analyzed. Not only have micellar systems of different nature been included but also microemulsions, polymeric, and liposomial phases. In order to compare the systems, a principal component analysis of the coefficients of the solvation equation is performed. From this analysis, direct information of the system properties, differences in selectivity, as well as evidence of lack of accuracy in some system characterizations are obtained. These results become a very useful tool to perform separations with mixtures of surfactants, since it is possible to know which mixtures will provide a greater selectivity variation by changing only the composition of the pseudostationary phases. Furthermore, the variation of the selectivity of some mixtures, as well as the effect of the addition of organic solvents on selectivity, is also discussed.

Cationic surfactants for micellar electrokinetic chromatography: 1. Characterization of selectivity using the linear solvation energy relationships model

“…Among micelles of anionic surfactants, the structure of the ionic head group has been shown to be the dominant factor in controlling EKC selectivity [6]. A collective comparison of EKC PSPs shows that cationic surfactants provide significantly different selectivity than other PSPs [20]. However, relatively few cationic surfactants have been studied compared to anionic surfactants.…”

Recent progress in the use of ionic polymers as pseudostationary phases for EKC

“…In an approach similar to that suggested by Fuguet et al [34], complexes of polyacrylic acids with cationic surfactants have been employed and characterized as PSPs. In the most recent study, the selectivity of the complexes is studied as a function of composition [37].…”

“…Fuguet et al [34] used principal components analysis (PCA) to classify 55 PSPs, including 22 polymeric PSPs as well as liposomal systems and a microemulsion, using LSER results from the literature. Two principal component axes were found to nearly completely account for the variance.…”

Retention behavior and selectivity of a latex nanoparticle pseudostationary phase for electrokinetic chromatography

“…The coefficients (v, s, a, b, and e), determined from the regression analysis, provide relative measures of the interactive nature of the PSP compared to the BGE and correspond to cohesivity and dispersive nature (v), ability to interact with non-bonding and p-electrons of the solute (e), polarity and polarizability (s), hydrogen-bond accepting ability (a), and hydrogen-bond donating ability (b). The LSER approach has been applied extensively to the characterization of PSPs and to compare and classify their selectivities [16,24].…”

“…One useful means to normalize the parameters is to divide by the following normalization parameter [16,69]:…”