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

Fused-silica capillary tubes with 50-mu m bores have been chemically modifi ed to yield odadecyl-derivatized surfaces with increased surface area. Alky lation is achieved in three steps: etching, silane adlayering, and olefin h ydrosilation. Surface roughness, surface area, surface-tip attractive force s, and topographic images of the native, etched, silane-adlayered, and alky lated capillary bores as measured by atomic force microscopy are presented here. Significant roughening occurs during the etching process, but the mos t dramatic change in roughness and surface adhesion forces occurs in the hy drided (silane-adlayered) capillary surface. Topographic smoothing and pass ivation of surface activity are observed for the alkylated capillary surfac e.