Statistical evaluation of linear solvation energy relationship models used to characterize chemical selectivity in micellar electrokinetic chromatography

Electrokinetic chromatographic characterization of novel pseudo‐phases based on N‐alkyl‐N‐methylpyrrolidinium ionic liquid type surfactants

“…Moreover, [C n MPY] 1 imparts to the fused-silica capillary wall a permanent charge not subject to pH-induced variations in ionization so long as the ionic attraction between anionic silanols and the cationic surfactant is not perturbed. These results are reminiscent of those obtained by Stalcup and co-workers using short-chain [C 2 The general characteristics of CTAB and C n MPYB-based pseudo-phases are listed in Table 2. The electrophoretic mobilities of the micelles do vary significantly between the a) The errors reported in parentheses are the standard errors, 6s/N.…”

“…Consistent with the latter value is the fact that, in the case of dihexadecyldimethylammonium bromide, bromide counterions remain tightly bound to the vesicle surface (b , 0.01). Anionic micelles, on the other hand, possess m values from 2.0 for lithium perfluorooctane sulfonate (LiPFOS) [6] and 2.3 for the bile salt detergent sodium cholate [6] to 2.7-3.0 for SDS, depending on conditions and counter-ion valency [2,3,6,8]. The C n MPYB series, despite being a linear surfactant and not being fluorinated, yields values of m ranging from 2.4 to 2.7 and a composite value of 2.52 6 0.30, without any clear trend with chain length.…”

“…The selectivity of MEKC separations is primarily determined by the choice of micelle-forming surfactant. Multiple studies have been performed characterizing the selectivity of micellar [1][2][3][4][5][6], polymeric [7], vesicular [8,9], and liposome [10][11][12] pseudostationary phases. Among micellar pseudostationary phases, cationic surfactants provide selectivity significantly different from anionic surfactants [2,5,6].…”

“…In some cases, the rR 2 term has been referred to as the polarization/polarizability correction term for the LSFER model, and therefore, r may represent polarizability of the micellar phase that is not accounted for by s [36]. The multiparameter LSFER model developed by Abraham provides statistical treatment of all data and has been used extensively to characterize various pseudophases in EKC and MEKC [1][2][3][4][5][6][7][8][9]12].…”

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

“…2), two of them with fluorinated hydrophobic side chains, were characterized with respect to performance and selectivity in EKC [31]. This was the first report of fluorinated polymeric PSPs, and it was anticipated that these polymers would provide highly unique selectivity akin to that which had been reported previously for lithium pefluorooctane sulfonic acid (LiPFOS) [32,33]. However, none of the polymers had selectivity similar to LiPFOS, and the selectivity of analogous hydrocarbon and fluorocarbon polymers were very similar.…”