Abstract: The invention is in concern of a method for measuring the electrophoretic mobility of particles in a liquid test sample in order to improve the precision of the electrophoretic measurement and to reduce in particular the operational expenditures in such a method.By use of considerably simple means a very precise time measurement of the mobility of particles is obtained free from any subjective influences with respect to the selection of the particles to be evaluated and to the time measurement. Accordingly, signals variable with respect to their frequency and visualized on the screen of a monitor are derived from out of video synchronization pulses, said signals are logically combined to the digitalized adjustable image scanning signals, improved in their signal-to-noise ratio.The output signals of this combination effect a counting operation dependent on the particle mobility.

Abstract: The invention is in concern of a method and a device for moving a liquid sample material in a measuring chamber, particularly for use in electrophoretic measurements. To permit precise measurements the remaining sample material is prevented from mixing with the sample material under test. The valves employed have to be closed in the course of the sample movement. This is realized in displacing the sample material by means of two pistons rigidly connected to each other and arranged in a by-pass of the measuring chamber.