Pranaityte Birutë, Padarauskas Audrius
Department of Analytical and Environmental Chemistry, Vilnius University, Vilnius, Lithuania.
Electrophoresis. 2006 May;27(10):1915-21. doi: 10.1002/elps.200500386.
Manipulation of the EOF is essential for achieving optimal separations by MEKC. In this paper, we present an extensive investigation of the effect of common experimental conditions on the EOF observed in a capillary coated with poly(diallyldimethylammonium chloride) (PDADMA) polyelectrolyte under MEKC conditions. It was found that highly reproducible cathodal EOF is achieved approximately at or just below the conditional CMC value of SDS in the electrolytes used. At concentrations of SDS greater than the CMC the EOF is independent of pH. The impact of common organic modifiers (ACN, methanol, urea, beta-CD and nonionic surfactant) on the EOF behavior in both a PDADMA-coated capillary and a bare silica capillary is compared. The suppressing effect of organic modifiers on the EOF is much stronger for coated capillary indicating that these compounds additionally reduce the negative charge density on the capillary surface due to alteration of the surfactant coating.
操纵电渗流对于在毛细管胶束电动色谱法（MEKC）中实现最佳分离至关重要。在本文中，我们对常见实验条件对在MEKC条件下涂有聚二烯丙基二甲基氯化铵（PDADMA）聚电解质的毛细管中观察到的电渗流的影响进行了广泛研究。结果发现，在所使用的电解质中，大约在SDS的条件临界胶束浓度（CMC）值或略低于该值时可实现高度可重现的阴极电渗流。在SDS浓度大于CMC时，电渗流与pH无关。比较了常见有机改性剂（乙腈、甲醇、尿素、β-环糊精和非离子表面活性剂）对涂有PDADMA的毛细管和裸硅胶毛细管中电渗流行为的影响。对于涂覆毛细管，有机改性剂对电渗流的抑制作用要强得多，这表明这些化合物由于表面活性剂涂层的改变而额外降低了毛细管表面的负电荷密度。
