GLASS CHIPS FOR HIGH-SPEED CAPILLARY ELECTROPHORESIS SEPARATIONS WITH SUBMICROMETER PLATE HEIGHTS

Micromachined capillary electrophoresis systems with integrated sample injection have been fabricated on glass chips using standard photolithographic and etching techniques. The injector permits volume-defined electrokinetic sample injection without sample biasing. Utilization of short separation capillaries and high field strengths in combination with a small sample plug length results in both fast and efficient separations of fluorescein isothiocyanate- (FITC-) labeled amino acids. Analysis times range from a few seconds to a few tens of seconds with corresponding plate numbers of 5800-160 000, respectively. Plate heights down to 0.3 mum have been obtained using a separation length of 24 mm and an electric field of 1 kV/cm. As it turns out, a maximum separation efficiency has been reached, limited only by diffusion and the effects of both injection and detection. Automated repetitive sample injection and separation on a time scale of seconds is demonstrated and provides a route to quasi-continuous on-line monitoring of chemical species in a sensorlike fashion.