OPEN-CHANNEL ELECTROCHROMATOGRAPHY ON A MICROCHIP

A glass microchip having a channel with a cross section of 5.6 mu m high and 66 mu m wide was fabricated using standard photolithographic and etching techniques. The surface of the channel was chemically modified with octadecylsilane to function as the stationary phase for open channel chromatography. Electroosmotic now was used to ''load'' the sample into the microchip and to ''pump'' the mobile phase during the experiments. For electric field strengths in the separation column from 27 to 163 V/cm, the linear velocity for the electroosmotic flow ranged from 0.13 to 0.78 mm/s. Detection was performed using direct fluorescence for separation monitoring and indirect fluorescence for void time measurements. Plate heights as low as 4.1 and 5.0 mu m were generated for unretained and retained components, respectively.