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-electroc hemical detection experiments is described. Both plug injections and c ontinuous migration experiments in 8-mu m-internal-height channels are used to evaluate lateral dispersion. The width of dopamine plugs (60 a), at 4 sigma, 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 c apillary and channel voltages used. This results in a unique separatio n achieved in the channel for every 3.3 s of continuous sample introdu ction. Experimental parameters that might be used to minimize lateral dispersion have been studied. Electric field ratios, between the capil lary and channel, of < 1.5 provide optimal results for these experimen ts. In addition, the rate of capillary movement is shown to be a criti cal parameter in channel-based separations with the new detection sche me. (C) 1998 John Wiley & Sons, Inc.