Abstract: The liquid microcolumn chromatograph comprises a microcolumn (1), unit (2) for feeding eluent, made as a reservoir (3) separated by a "slack" diaphragm (4) into two half-chambers (5,6) one whereof communicates with a source (7) of pressure and the other is connected to a source (8) of eluent and to an inlet into the microcolumn (1) a flow-through cell (9), and an eluent-collecting vessel (14). The chromatograph is provided with an additional reservoir (10) separated by a "slack" diaphragm (11) into two half-chambers (12, 13) and is also provided with an additional source (15) of pressure, the half-chamber (12) being communicated with an outlet of the flow-through cell (9) and connected to the eluent-collecting vessel (14), whereas the half-chamber (13) communicates with the additional source (15) of pressure.

Abstract: A device for preparing a gradient solution for a high-pressure liquid chromatograph comprises vessels (1) containing eluents, a switch-over unit (7), a piston pump (9) and a mixer (4). Each vessel (1) containing eluents has a movable partition (10) dividing it into two chambers (11,12). The switch-over unit (7) is fashioned as a flow-through chamber (13) accommodating a rotary switch-over valve having a rotor (15) and stator (16). The rotor (15) has one through passage (17), whereas the stator (16) is provided with through passages (18) equal in number to the number of vessels (1) each communicating with the corresponding vessel (1) and arranged so that during rotation of the rotor (15) the through passage (17) provided therein is capable of connecting alternately to the passages (18) of the stator (16).