Characterization of Lateral Dispersion in Microfabricated Electrophoresis-Electrochemical Array Detection

Characterization of the analyte dispersion occurring perpendicular to the applied electric field in microfabricated electrophoresis-electrochemical detection experiments is described. Both plug injections and continuous migration experiments in 8-μm-internal-height channels are used to evaluate lateral dispersion. The width of dopamine plugs (60 s), at 4σ, or the effective zone width in the time dimension, has been determined to range from 1.2 to 1.8 mm and is dependent on the capillary and channel voltages used. This results in a unique separation achieved in the channel for every 3.3 s of continuous sample introduction. Experimental parameters that might be used to minimize lateral dispersion have been studied. Electric field ratios, between the capillary and channel, of < 1.5 provide optimal results for these experiments. In addition, the rate of capillary movement is shown to be a critical parameter in channel-based separations with the new detection scheme.