Chromatographic analysis with low pressure dual gradient refocusing

A system for separation of analytes in a liquid sample, said system comprising:

• a control unit for controlling and regulating flow rate and pressure of the system;
• a disposable cartridge enclosing a sorbent for binding the analytes in the liquid sample;
• a recipient socket for receiving the disposable cartridge, wherein a mobile phase flows through the cartridge into the recipient socket, thereby eluting the analytes into the recipient socket to form eluted analytes;
• a first conduit in fluid communication with the recipient socket, said conduit establishing a fluid link to a holding loop, wherein the holding loop has a volume below 200 μL and a length of at least 2 meters and is configured to store one or more mobile phase gradients and the eluted analytes;
• one or more first fluid pumps connected in parallel and controlled by the control unit to optionally establish the one or more mobile phase gradients and to deliver a mobile phase at a flow rate of 300 nL/min to 50 μL/min through said cartridge at a pressure of 1 bar to 50 bar;
• one or more second fluid pumps connected in parallel and controlled by the control unit to optionally establish the one or more mobile phase gradients and to deliver a make-up flow rate, at a location between the recipient socket and a holding loop, of 300 nL/min to 50 μL/min at a pressure of 1 bar to 50 bar;
• and
• one or more valves constructed to switch between a low pressure position and a high pressure position, wherein said low pressure position establishes a fluid connection from the cartridge to the holding loop, and said high pressure position disconnects the fluid connection of the holding loop from the cartridge and establishes a fluid connection of the holding loop with a high pressure fluid pump and a second conduit leading to a chromatography column, wherein the control unit is adapted to activate the high pressure fluid pump and force the one or more mobile phase gradients and the eluted analytes in said loop through the chromatography column at a flow rate of 20 nL/min to 20 μL/min and a pressure of 1 bar to 3,000 bar.

A system for separation of analytes in a liquid sample, said system comprising:

• a control unit for controlling and regulating flow rate and pressure of the system;
• an inlet for introducing the liquid sample into the system;
• a first column having a sorbent for trapping the analytes, said first column being configured to switch between a trapping mode and an elution mode, said trapping mode providing the inlet in fluid communication with the first column, and said elution mode providing elution of the analytes trapped in the first column to form eluted analytes;
• one or more holding loops configured to store one or more mobile phase gradients and the eluted analytes from the first column, the one or more holding loops each having a volume below 200 μL and a length of several meters;
• one or more first fluid pumps connected in parallel and controlled by the control unit to establish a mobile phase comprising the one or more mobile phase gradients and deliver the mobile phase at a flow rate of 300 nL/min to 50 μL/min through said first column at a pressure of 1 bar to 50 bar, when the first column is in said elution mode;
• one or more second fluid pumps connected in parallel and controlled by the control unit to deliver a make-up flow rate, at a location between the first column and the one or more holding loops, of 300 nL/min to 50 μL/min at a pressure of 1 bar to 50 bar;
• wherein all of said one or more first fluid pumps and said one or more second fluid pumps are controlled by the control unit to establish said mobile phase gradient;
• and
• one or more valves constructed to switch between a low pressure position and a high pressure position, wherein said low pressure position establishes a fluid connection from the first column to the one or more holding loops, and said high pressure position establishes a fluid connection between a high pressure fluid pump and the one or more holding loops and a conduit leading to a chromatography column, wherein the control unit is adapted to activate the high pressure fluid pump and force the one or more mobile phase gradients and the eluted analytes in said one or more holding loops through the chromatography column at a flow rate of 20 nL/min to 20 μL/min and a pressure of 1 bar to 3,000 bar.