HPLC sample introduction with bypass channel

A liquid separation system for separating sample fluid compounds, the liquid separation system comprising:

• a separation unit configured to separate compounds of a sample fluid in a mobile phase;
• a mobile phase drive configured to drive the mobile phase through the separation unit;
• a sample providing apparatus configured to provide the sample fluid;
• a sample dispatcher configured to receive the sample fluid from the sample providing apparatus, and configured to introduce a plurality of portions of the sample fluid into the mobile phase, the sample dispatcher comprising:
• a valve comprising an input and an output, the output coupled to the separation unit, and the valve configured to be switched to a loading state and to a dilution state;
• a sample reservoir coupled between the input and the output;
• and
• a bypass channel coupling the input of the valve to the output of the valve;
• and
• a controller configured to:
• switch the valve to the loading state, at which the sample reservoir is fluidly coupled to the sample providing apparatus and receives at least one portion of the plurality of portions of the sample fluid;
• switch the valve to the dilution state, at which the sample reservoir and the bypass channel are fluidly coupled in parallel flow paths between the mobile phase drive and the separation unit, and the parallel flow paths join at a point upstream of the separation unit, wherein:
• the mobile phase is driven through the sample reservoir and the bypass channel via the parallel flow paths;
• and
• the at least one portion of the plurality of portions of the sample fluid is driven with the mobile phase from the sample reservoir to the separation unit, and is diluted by the mobile phase from the bypass channel, and
• wherein switching states of the valve comprise a) a first switching state which fluidly couples only the sample reservoir between the mobile phase drive and the separation unit, b) a second switching state which fluidly couples both the sample reservoir and the bypass channel between the mobile phase drive and the separation unit, and c) a third switching state which fluidly couples only the bypass channel between the mobile phase drive and the separation unit.

A sample dispatcher configured for individually introducing a plurality of portions of a sample fluid into a flow of a mobile phase of a separation system configured for separating compounds of one or more sample fluids, wherein the separation system comprises a mobile phase drive configured for driving the mobile phase through a separation unit configured for separating compounds of the sample fluid in the mobile phase, the sample dispatcher comprising:

• a valve comprising at least an input and an output, the output coupled to the separation unit;
• a sample reservoir coupled between the input and the output;
• a bypass channel coupling the input of the valve to the output of the valve,
• and the valve is switchable to a state such that the bypass channel is not coupled between the mobile phase drive and the separation unit, wherein:
• the sample dispatcher is configured to selectively switch the valve to a loading state and a dilution state;
• at the loading state, the valve defines a flow path into the sample reservoir, wherein the sample reservoir receives and temporarily stores at least one portion of the plurality of portions of the sample fluid;
• at the dilution state, the valve fluidly couples the sample reservoir and the bypass channel in respective parallel flow paths between the mobile phase drive and the separation unit, the parallel flow paths joining at a point upstream of the separation unit, wherein:
• the mobile phase is driven through the sample reservoir and the bypass channel via the parallel flow paths;
• and
• the at least one portion of the plurality of portions of the sample fluid is driven with the mobile phase from the sample reservoir to the separation unit, and is diluted by the mobile phase from the bypass channel;
• and
• wherein switching states of the valve comprise a) a first switching state which fluidly couples only the sample reservoir between the mobile phase drive and the separation unit, b) a second switching state which fluidly couples both the sample reservoir and the bypass channel between the mobile phase drive and the separation unit, and c) a third switching state which fluidly couples only the bypass channel between the mobile phase drive and the separation unit.