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

Abstract

MEKC and the linear solvation energy relationship (LSER) model have been applied to two series of cationic surfactants. The synthetic flexibility of the quaternary ammonium group is exploited to generate the two series, one consisting of linear substitutions and the other incorporating the ammonium into ring structures of varying size. The effects of the head group structure on the CMC, aggregation number, and electrophoretic properties of the surfactants were determined. These surfactants were also characterized with the LSER model, which allowed the contributions of five chemical factors to the interactions between solutes and the micelles to be evaluated. Trends were observed in the cohesivity and polarity of the linear surfactant series, with both increasing with the size of the head group. No trends in the LSER parameters were observed in the cyclic series, but the LSER results do show that the surfactants with cyclic head groups provide a significantly different solvation environment from the linear series. Additional trends were observed in the aggregation behavior and chromatographic properties of the surfactants. These included changes in the CMCs, aggregation numbers, EOF, and electrophoretic mobility of the micelles that correlate to changes in head group size.

Cationic surfactants for micellar electrokinetic chromatography: 2. Representative applications to acidic, basic, and hydrophobic analytes

“…Our group has recently reported the synthesis of two series of cationic surfactants with systematically varied headgroup structure and the characterization of their retention and selectivity in EKC using the linear solva-tion energy relationship (LSER) model [10]. Our results showed that slight structural changes to the headgroups of cationic surfactants produce significant changes in retention and selectivity.…”

Linear Free Energy Relationship Correlation of The Distribution of Solutes Between Water And Cetytrimethylammonium Bromide (CTAB) Micelles

“…Study of Schnee and Palmer [9] Logk CTAB ¼ NA þ 0:65ð0:13ÞE À 0:58ð0:11ÞS þ 1:06ð0:09ÞA À 2:77ð0:18ÞB þ 3:28ð0:22ÞV ð12Þ …”

“…Schnee and Palmer [9] did not report a numerical value for the constant, nor did the authors give the complete statistical details for their derived correlation. Examination of Equations 11 -13 reveals that the Abraham model does provide a very good mathematical description of each of the three log k CTAB datasets.…”

“…The published log K S,CTAB/water correlation of Quina and coworkers [6], see Equation 6, was based on only 54 experimental values. Published retention factor correlations (correlated as the logarithm of the retention factor) of Fuguet et al [7], Poole and Poole [8], and Schnee and Palmer [9] were based on datasets containing 56, 36, and 40 compounds, respectively. We assess the predictive ability of our derived correlation model through training set and test set analysis.…”

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

“…The identity and LSER descriptors of 40 compounds are presented in [13]. The current study used the same compounds, minus bromobenzene, for a total of 39 analytes.…”