Migration mechanism of bases and nucleosides in oil-in-water microemulsion capillary electrophoresis

Abstract

The electrophoretic behaviors of five bases and corresponding nucleosides in the oil in water (o/w) microemulsion capillary electrophoresis, microemulsion electrokinetic chromatography (MEEKC), were examined in comparison with those in normal capillary zone electrophoresis (CZE). The microemulsion systems were composed of heptane, sodium dodecyl sulfate (SDS), 1-butanol and 10 mM phosphate buffer (pH 7.0) or toluene, SDS, 1-butanol and 5 mM carbonate buffer (pH 10.0). CZE was carried out in the range of pH 9.7-10.9, and the dissociation constants, pKa, of the bases and nucleosides and the electrophoretic mobilities of the anionic forms were determined. The electrophoretic behaviors of the solutes in the microemulsion systems were analyzed from their pKa, the electrophoretic mobilities of the anions determined by CZE, and the distribution constants, K(D), of the neutral forms between the microemulsion droplets and the outer aqueous phase. The importance of adsorption mechanism in MEEKC system was suggested from the correlation between log K(D) and log P.

Etched succinate‐functionalized silica hydride stationary phase for open‐tubular CEC

“…Certainly, they will be retained under a consideration of complex mechanism. According to Watarai's report 33, the p K a values of bases and nucleosides are calculated from their corresponding values of apparent electrophoretic mobility in a CZE system with 0.1 M ammonium acetate buffer, which shows the data for Thd (10.5), Thy (10.2), Urd (10.0), and Guo (10.0). Data for Cyd (12.5) and Ado (12.4) could be found in 34.…”

Twenty‐one years of microemulsion electrokinetic chromatography (1991–2012): A powerful analytical tool

“…Generally, 1‐hexane , 1‐heptane and 1‐octane were commonly used. In addition, other water‐insoluble substances, cyclohexane , pentane , toluene , 1‐chloropentane , 1‐octanol , 1‐hexanol , were also attempted. However, some water‐soluble solvents as ethyl acetate , isopropylmyristate , and propylene glycol monomethyl ether acetate were reported in MEEKC studies.…”

Optimisation and use of water-in-oil MEEKC in pharmaceutical analysis

“…1 shows the L1 and the L2 phases where the composition of the microemulsion is determined. Microemulsions have unique properties as separation media and have been successful in the separation of a range of analytes in both high performance liquid chromatography (HPLC) [1][2][3] and microemulsion electrokinetic chromatography (MEEKC) [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18].…”