DISPERSION IN CAPILLARY ELECTROPHORESIS WITH EXTERNAL FLOW-CONTROL METHODS

Recently, methods for controlling the bulk how of the buffer which are independent of the electrophoretic migration have been demonstrated i n capillary electrophoresis (CE) systems. These methods include contro lling the electroosmosis by radially directed electric fields, and con trolling the bulk flow by siphoning. This paper investigates basic dis persion mechanisms at work by examining the dispersion of dimethyl sul foxide under various external control methods. It is found that the el ectroosmotic how control methods exhibit the same dispersive behavior as the conventional CE system. In particular, the results for pH 7 buf fers obey the theoretical expression for the plate height in all confi gurations. However, in all configurations, pH 2.7 buffers do not follo w the theory, and counter to intuition, additional pressure can improv e the plate height at pH 2.7. Taking all these methods together, one c an develop a technique to appropriately adjust the electrophoretic and bulk how to optimize resolution.