Characterization of inner surface phenomena in capillary electrophoresis capillaries by electron microscopy, atomic force microscopy and secondary ion mass spectroscopy

Abstract

Scanning electron microscopy (SEM), atomic force microscopy (AFM) and secondary ion mass spectroscopy (SIMS) were used to investigate the topography and physicochemical properties of fused-silica capillary inner surfaces. SEM is a quick and economical standard technique, e.g., it is used to investigate adsorption phenomena and to optimize the drawing processes. However, it is impossible to investigate coated capillaries, and vertical information is only vague. Here the use of AFM is advantageous, e.g., in deep grooves (down to 500 nm) using this technique. SIMS offers poor lateral resolution (1 μm), but a great deal of chemical information about adsorbates or immigration of ions into deeper glas layers. Other high-resolution techniques like X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) are not or not yet [scanning tunneling microscopy (STM), near-field scanning optical microscopy (NSOM)] practical techniques for investigating capillary electrophoresis (CE) capillaries.