THE EFFECT OF METAL CATIONS ON CAPILLARY ELECTROOSMOTIC FLOW
Eduardo De La Toba, Shane Wells, Christopher Harrison.
San Diego State University, San Diego, CA.
Capillary electrophoresis (CE) is an incredibly powerful tool in the field of chromatography due to its potential for high-resolution separations of analytes and the requirement for very small volumes of sample for analysis. Despite these attributes, one issue when performing separations with CE is that proteins can bind to the negatively charged silica surface on the interior of the capillary. To overcome this obstacle, phospholipids are used to prevent the binding of proteins to the surface. Traditionally, phospholipid bilayers are stabilized by calcium ions that are incorporated into the phospholipid bilayer in order to minimize the charge repulsion of the negatively charged phosphate groups on the heads of the phospholipids. It is known that the magnitude and direction of the electroosmotic flow (EOF) is influenced by the presence of calcium ions in the phospholipid bilayer. The objective of this work was to investigate how different metal cations might integrate into the bilayer and influence the EOF and the stability of the bilayer. We predicted that the incorporation of noncalcium metal cations into the bilayer would yield an overall positive charge of the bilayer and, in turn, the EOF based on the magnitude of the incorporation of the different metals. This has been supported by our work using a range of different divalent and trivalent metal cations in the separation buffer. We have shown that there is a significant impact on the magnitude of the EOF depending on the choice of the metal cation and with various EOF values.