Patent ID: 7939017

Claim:
An analytical system comprising: an analytical instrument having a detection zone; a sample holding station holding a plurality of samples; an injection port; a system fluid reservoir containing a system fluid; a sample probe which is movable between the samples in said sample holding station and said injection port and which transfers a selected sample from the sample holding station to the injection port; a first pump connected to the sample probe to draw the selected sample into the probe and to eject the selected sample into the injection port; a switching valve having a first position which connects the injection port to the detection zone to allow the first pump to deliver samples through the injection port to prime a flow path from the switching valve to the detection zone with sample; a second pump connected to the switching valve, wherein the switching valve has a second position which disconnects the injection port from the detection zone and connects the second pump to the detection zone, the second pump being operable to advance system fluid through the flow path to displace sample in the flow path and control the volume and the rate of movement of the sample primed by the first pump through the detection zone; and a controller which in a first mode selectively positions the switching valve in its first position and operates the first pump to deliver sample through the switching valve to prime the flow path to the detection zone and which in a second mode positions the switching valve in its second position and operates the second pump to deliver system fluid through the switching valve to advance the primed sample through the flow path to the detection zone.