Automated recycling free fluid isotachophoresis : Principle, instrumentation and first results

Abstract

Most investigations involving preparative isotachophoresis report the use of solid support media in which sample loads of up to 1 g are fractionated within several hours. Larger throughputs and simpler recovery of purified proteins have been achieved by continuous flow isotachophoresis. This method is based on a thin film of fluid flowing between two parallel plates with the electric field applied perpendicular to flow direction. Both the leading and the terminating electrolytes, as well as the sample, are continuously admitted to one end of the electrophoretic chamber and are collected through an array of outlet tubes at the other. In recycling isotachophoresis the effluent from each channel is reinjected into the cell through a corresponding influent port. The development of automated recycling isotachophoresis with a computer controlled counterflow of leading electrolyte is described together with its prospective use as a downstream processing unit operation in biotechnology.