Open‐tubular capillary electrochromatography using a polymeric surfactant coating

Abstract

A stable polyelectrolyte multilayer (PEM) coating was investigated for use in open-tubular capillary electrochromatography (o-CEC). In this approach, the PEM consisted of the cationic polymer of a quaternary ammonium salt, poly(diallyldimethylammonium chloride) and the anionic polymeric surfactant, poly(sodium undecylenic sulfate). Both the cationic and anionic polymers were physically adsorbed to the surface of a fused-silica capillary by use of a simple coating procedure. This procedure involved an alternate rinse of the positively and negatively charged polymers. The performance of the PEM coating as a dynamic stationary phase was evaluated by use of electrochromatographic experiments and showed good selectivity for both phenols and benzodiazepines. Reproducibility of the PEM coating was also evaluated by calculating the relative standard deviations (RSDs) of the electroosomotic flow (EOF). The run-to-run and capillary-to-capillary RSD values of the EOF were less than 1.5%. The endurance of the coating was more than 100 runs. The importance of the PEM coating was illustrated by comparing separations on a bare uncoated capillary with the coated capillary. In addition, the chromatographic performance using o-CEC and micellar electrokinetic chromatography (MEKC) was compared for the separation of benzodiazepines.

MEKC: An update focusing on practical aspects

“…This type of coating provides reproducible separations at a low pH (pH 3.0), with RSD values for migration times and peak areas better than 0.45 and 3.3%, respectively. Kamande et al [169] investigated the use of a PEM coating consisting of the cationic polymer PDADMA and the anionic polymeric surfactant poly(sodium undecylenic sulfate) (poly-SUS), both the cationic and anionic polymer being physically adsorbed onto the surface of a fused-silica capillary by use of a simple coating procedure. When used in MEKC, poly-SUS was added to the BGE, so that the analytes partitioned in the PSP; by contrast in CZE, the analytes partitioned in the stationary phase coating.…”

Polyelectrolyte‐modified short microchannel for cation separation

“…To stabilize the EOF, it has been proposed to control the pH of the eluent, or to fix the zeta potential of the capillary either by chemical modification or by adsorption. In the latter case, adsorption of polyelectrolytes is rather an easy route to achieve this goal [6][7][8][9][10]. Except for modulating the EOF, these adsorption methods, both covalent and noncovalent, have also been used to prevent nonspecific adsorption, or as a means to attach active molecules (such as antibodies) to the surface.…”

Method Development by Use of Capillary Electrophoresis and Applications in Pharmaceutical, Biological and Natural Samples

“…This usually provides higher efficiencies and rapid analysis. They have, over the years, been extensively used in a BGE [74][75][76][77][78][79][80], in a polyelectrolyte multilayer coating [63,74,[81][82][83], and in a CE-MS system [84][85][86].…”