Characterization of wall modified silica capillaries for OTCEC and CE

Fused silica capillaries with an i.d. of 50 and 75 mm are chemically modifi ed by the silanization/hydrosilation method to attach organic moieties for use in electrokinetic chromatography. An etching process was utilized to in crease the surface area of the capillary inner wall. A comparison of Si-C b onded capillary columns to those obtained by conventional organosilanizatio n (Si-O-Si-C) bond was performed. The etched capillaries after chemical mod ification are shown to have an anodic electroosmotic flow (EOF) below pH 4. 5 while the bare modified capillaries show a cathodic EOF at all pH's studi ed. The use of these etched chemically modified capillaries eliminates the need for frits and the difficulties associated with packed capillaries such as bubble formation. This open tubular approach to CEC is also suitable for an analysis of a number of different types of basic compounds.