FIELD: suction units for proportioning liquids. SUBSTANCE: proposed unit 1 has housing 2, end part 3 with open farthest end 6 for securing end-piece 8 detachably; end-piece 8 embraces space for placing liquid sample 10. End part 3 has device 5 which may perform reciprocating motion Suction unit 1 has detachable membrane member 11 mounted in air space for ensuring gas tightness; said air space is formed by cylindrical space 4 and space for sample in end-piece; it includes membrane made from liquid- and gas-tight flexible deformable material possessing property of restoring its form; device 5 may be brought in contact with this membrane. Method of proportioning liquid by means of above-mentioned unit consists in setting device 5 in motion towards farthest end 6 of end part 3 for contact with membrane, thus changing volume of space separated by membrane from air space in direction of end of end-piece 8 which may be introduced in liquid for drawing sample. Membrane is freed from end part 3 of suction unit by continuing motion of device 5 beyond position of drawing or removing sample. EFFECT: enhanced accuracy and reliability. 16 cl, 8 dwg
