Improved capillary electrophoresis frontal analysis by dynamically coating the capillary with polyelectrolyte multilayers

An improved CE-FA method using a polyelectrolyte multilayer (PEML) coated capillary is described. The coating was simply created by alternatively flushing the capillary with positively charged polyelectrolyte polybrene (HDB) and negatively charged polyelectrolyte dextran sulfate (DS). Human serum albumin (HSA) and 6 drugs were selected as an experimental model to evaluate such an improvement. The PEML coating was demonstrated to effectively reduce the protein adsorption on the capillary wall. Compared with the uncoated capillary, the repeatability (RSD%) of the EOF mobility and the plateau height of free drug were improved significantly from 3.7% to 0.51% and from 0.61% to 0.34%, respectively. No interference of the coating on the measurement of protein–drug binding parameters was observed.