Rapid electrophoretic and chromatographic analysis on microchips

Rapid, high-performance electrokinetically-driven separations are easily incorporated into microfabricated devices. The first example is an electrophoretic separation of a binary mixture that was completed in less than 1 millisecond. A separation field strength of 53 kV cm(-1) was used (8.6 kV applied to the microchip), and the separation was monitored 200 mu m downstream from the injection valve. The second separation technique described is solvent-programmed open-channel electrochromatography. Using a microchip with its channel walls coated with a C-18 stationary phase and applying a five second, linear gradient, a sample of coumarin dyes was resolved in just under 20 seconds.