PLANAR GLASS CHIPS FOR CAPILLARY ELECTROPHORESIS - REPETITIVE SAMPLE INJECTION, QUANTITATION, AND SEPARATION EFFICIENCY

A sample injection system and a capillary electrophoresis channel integrated together on a planar glass substrate are described, and the performance is evaluated. Voltages of at least 25 kV may be applied over an 11-cm-long capillary channel with sufficient dissipation of the Joule heat generated (1.8 W/m). The glass substrate sustains at least 10(5) V/cm dc without dielectric breakdown. Using laser-induced fluorescence detection, mixtures of fluorescein derivatives and fluorescein isothiocyanate-labeled amino acids were injected and separated. Up to 100 000 theoretical plates and approximately 20 plates/V were obtained under optimized conditions, comparable to results with fused-silica capillaries. Quantitative analysis showed that peak areas were proportional to the amount injected for injected plug lengths greater than 200 mum. The presence of two rectangular corners in a 0.85-cm-long separation channel did not increase dispersion detectably, indicating a serpentine capillary channel 0.5 m in length could be fabricated in less than a 1-cm2 area.