Abstract: A burette tip (1) for metering a titrating agent consists essentially of a burette body (10) with a seat (3) for a membrane and with such a membrane (2). The burette tip (1) comprises, for protecting the membrane (2) and the seat (3) against mechanical damage, a covering (4, 5, 15) which at least partly encloses and covers the membrane (2) and the seat (3). The membrane (2) is clamped between the burette body (10) and a cover part (5) and is held in the burette body (10).

Abstract: In order to regenerate a plurality of suppressors (6, 6a, 6b) that are inserted alternatingly into a device for ion-exchange chromatography, apart from an analysis branch (9), at least one additional treatment branch (10, 10a) is anticipated, through which a treatment agent (7, 7a) can be fed. The analysis branch (9) and the treatment branch (10, 10a) each possess a gap (34) in which the suppressors (6, 6a, 6b) can be alternatingly inserted. In order to insert a suppressor in a pipework branch, the suppressor is moved relative to the pipework branch until the connection openings (36a, 36b) of the suppressor are aligned with the corresponding pipe openings (35) of the gap of the pipework branch concerned.

Abstract: A volume measurement and dosage device possesses a cylinder- piston- and valve-system (4). With this system, liquid can be drawn up and/or delivered in defined quantities. At least two channels (33, 36, 38) are provided in the valve-system, which can be connected with at least one opening (32) in the cylinder bottom (11). The piston (12) is displaceable within the cylinder (10) by means of an actuation device (3). The cylinder (10) is at the same time surrounded by a holding device (5, 40), in which it is mounted in bearings to rotate with the cylinder bottom (11) around an axis common to the longitudinal axis of the cylinder (Y) or parallel to it. The cylinder bottom (11), with at least two channel openings (29, 30, 31), rests with a sealed seating upon a valve element (28). Through rotation of the cylinder bottom (11), its opening (32) can alternately be aligned with the channel openings (29, 30, 31) of the valve element (28).