Characterization by atomic force microscopy of fused-silica capillaries chemically modified for capillary electrokinetic chromatography

Abstract

Fused-silica capillary tubes with 50-μm bores have been chemically modified to yield octadecyl-derivatized surfaces with increased surface area. Alkylation is achieved in three steps: etching, silane adlayering, and olefin hydrosilation. Surface roughness, surface area, surface - tip attractive forces, and topographic images of the native, etched, silane-adlayered, and alkylated capillary bores as measured by atomic force microscopy are presented here. Significant roughening occurs during the etching process, but the most dramatic change in roughness and surface adhesion forces occurs in the hydrided (silane-adlayered) capillary surface. Topographic smoothing and passivation of surface activity are observed for the alkylated capillary surface.