Investigation of the chiral surfactantN-dodecoxycarbonylvaline in electrokinetic chromatography: Improvements in elution range and pH stabilityvia mixed micelles and vesicles, and the hydrophobicity determination of basic pharmaceutical drugs

Abstract

The chiral surfactant dodecoxycarbonylvaline (DDCV) has proven to be an effective pseudostationary phase for the separation of many enantiomeric pharmaceutical compounds. In this study the elution range and the prediction of octanol-water partitioning for the DDCV micellar system was examined. Through incorporation of DDCV in mixed micelles and unilamellar vesicles, enhancement of the elution range was observed. The mixed micelles contained a second anionic surfactant, sodium dodecyl sulfate (SDS), while the vesicles were composed of DDCV and the cationic surfactant cetyltrimethylammonium bromide (CTAB). Enantioselectivity, as well as other chromatographic and electrophoretic parameters, were compared between the mixed micelles, vesicles, and DDCV micelles. The hydrophobicity of the DDCV system was also evaluated as a predictor of n-octanol-water partition coefficients for 15 beta amino alcohols. The correlation between the logarithm of the retention factor (log k) and log P(ow) for seven hydrophobic beta-blockers and eight beta-agonists were r2 = 0.964 and r2 = 0.814, respectively.

Analysis of liposomes by capillary electrophoresis and their use as carrier in electrokinetic chromatography

“…[18] by substitution of the carbonyl by a benzoyl group, was investigated by dynamic light scattering, microscopy, fluorescence probe and surface tension methods [19]. It spontaneously forms vesicles with 30-70 nm diameter in aqueous solutions.…”

“…LFER analysis suggested a difference in solute-vesicle interaction due to the counter-ion. The elution range for EKC with particles containing chiral N-dodecoxycarbonylvaline (DDCV) was increased by applying mixed vesicles with an oppositely charged detergent, CTAB [18]. The vesicle-based separation system finally consisted of 1.4% (w/v) CTAB/DDCV (30/70 mol%) in 35 mM CHES buffer, pH 8.5.…”

Effect of class I and II organic modifiers on retention and selectivity in vesicle electrokinetic chromatography

“…The electrophoretic mobility of the vesicle, m ep, ves , was calculated using an iterative computational method which maximizes the square of the correlation coefficient (r 2 ) of a regression line of log k vs. n CH2 , where n CH2 is the number of methylene groups of a homologous series of alkylphenones [25]. The retention factor, k, for charged solutes is calculated as:…”

Hexafluoroisopropanol-modified cetyltrimethylammonium bromide/sodium dodecyl sulfate vesicles as a pseudostationary phase in electrokinetic chromatography

“…Since then, mixed surfactant vesicles spontaneously formed from oppositely charged single chain surfactants, also referred to catanionic surfactant vesicles, have attracted increasing attention in EKC. Catanionic surfactant vesicles composed of cetyltrimethylammonium bromide (CTAB) and N-dodecoxycarbonylvaline (DDCV) [3], CTAB and sodium octyl sulfate (SOS) [4][5][6][7][8], octyltrimethylammonium bromide (OTAB) and SDS [5], cetyltrimethylammonium chloride (CTAC) and SOS [8], as well as octyltriethylammoniumbromide (C 8 NE 3 Br) and sodium dodecyl benzene sulfonate (SDBS) [9,10], have been successively examined as PSP in EKC. Compared to micelles, catanionic surfactant vesicles have much larger size, greater surface charge density that allows strong electrostatic interactions, and alternative hydrophobic-hydrophilic discriminatory power provided by the hydrophobic region of the vesicle bilayers [2,5].…”