Abstract: A fluid-tight connection of capillary channels in components which are detachable from each other is established with the use of a sealing element. In order to compensate for slight deviations between the channel axes during the coupling of the components without creating any dead spaces, the sealing element is configured as a piece of flexible tubing adapting to the course of the capillary channels during component coupling, and a mounting element anchored in one of the components.

Abstract: In order to avoid dead volumes in a valve for control of a branch line departing from the main line in a valve chamber located in a valve housing, the valve chamber contains an elastomer part provided with a main channel and a branch channel departing from it, and the two ends of the main channel are sealingly connected with the main lines. The free end of the branch channel is sealingly connected with the branch line, and further that a valve lifter be provided in the valve housing, which acts on the branch channel in the branch-off area directly adjacent to the main channel of the elastomer part, thus reducing the cross-section of the branch channel, which is held in place by a counterpiece in the valve housing.

Abstract: An electrode arrangement includes at least one potentiometric measuring electrode located in a sample channel, a reference electrode located in a branch line, and a suction pump downstream of the diaphragmless entrance opening of the branch line into the sample channel the reference electrode being an ion-sensitive, i.e., preferably chloride-sensitive, membrane electrode.