Device and method to sample liquids with high-precision in an automated sample analyzer

A sampling unit (100) to dispense a precise volume of liquid sample from a sample container (50) in an automated analytical instrument, the sampling unit comprising:

• at least one pump unit;
• at least one drive unit;
• a control unit operably connected to control the at least one pump unit and the at least one drive unit;
• an elongated hollow sampling member (10) comprising a first end including a sampling tip (12) and a second end (14), where in the sample member extends along a longitudinal axis between the first and second ends, and the second an end (14) is connected to a pump unit of the at least one unit;
• wherein the sampling member (10) is adapted to move between a first position and a second position via operation of a drive unit of the at least one drive unit, and the sampling tip (12) is adapted to be filled, in said first position, with liquid sample from the sample container through aspiration by one pump unit of the at least one pump unit;
• and
• a liquid-sampling valve (20) fluidically connected to the at least one pump unit and the sampling member, the liquid-sampling valve having a valve body comprising a flow structure including an inlet and an outlet, said flow structure including an aliquoting chamber (18) having a volume fluidically connectable to the inlet and outlet, the liquid-sampling valve (20) being selectively operable in either of both:
• (i) a first valve position in which the flow structure is adapted to be loaded with liquid sample through the inlet, said liquid sample is provided directly from the sampling tip (12) in the second position of the sampling member (10), and
• (ii) a second valve position in which the flow structure is adapted to dispense the volume of liquid sample through the outlet,
• wherein said aliquoting chamber (18) is configured to provide the volume of liquid sample via segmenting the liquid sample loaded into the flow structure in the first valve position;
• wherein the sampling tip (12) is adapted to discharge, in said second position of the sampling member, liquid sample through expelling by one pump unit of the at least one pump unit;
• and
• wherein the liquid-sampling valve (20) further defines, in the first second valve position, a guiding channel extending through the valve body in parallel with the longitudinal axis of said sampling member, said guiding channel configured to allow movement of the sampling member (10) between said first and second positions of the sampling member through the valve body, and
• wherein in the first valve position, the inlet is located within a same volume portion of the valve body that is occupied by the guiding channel in the second valve position and the inlet is located at a position shifted away from a central axis of the guiding channel.