Abstract: A solvent delivery system for a liquid chromatography system may include a first gradient proportioning valve in fluidic communication with a first plurality of sources of solvent and producing therefrom a first low-pressure gradient stream. The solvent delivery system may further include a second gradient proportioning valve in direct fluidic communication with an inlet of the first gradient proportioning valve and with a second plurality of sources of solvent, the second gradient proportioning valve producing a second low-pressure gradient stream from the second plurality of sources of solvent, wherein one solvent source of the first plurality of sources of solvent used by the first gradient proportioning valve to produce the first low-pressure gradient stream comprises the second low-pressure gradient stream. The solvent delivery system may also include a first pump in direct fluidic communication with the first gradient proportioning valve to receive and pressurize the first low-pressure gradient stream.

Abstract: A solvent delivery system for a liquid chromatography system may include a first gradient proportioning valve in fluidic communication with a first plurality of sources of solvent and producing therefrom a first low-pressure gradient stream. The solvent delivery system may further include a second gradient proportioning valve in direct fluidic communication with an inlet of the first gradient proportioning valve and with a second plurality of sources of solvent, the second gradient proportioning valve producing a second low-pressure gradient stream from the second plurality of sources of solvent, wherein one solvent source of the first plurality of sources of solvent used by the first gradient proportioning valve to produce the first low-pressure gradient stream comprises the second low-pressure gradient stream. The solvent delivery system may also include a first pump in direct fluidic communication with the first gradient proportioning valve to receive and pressurize the first low-pressure gradient stream.

Abstract: A liquid chromatography system includes a gradient proportioning valve in fluidic communication with sources of solvent. From the solvent sources, the gradient proportioning valve produces a low-pressure gradient stream. A first pump is in fluidic communication with the gradient proportioning valve to receive, pressurize, and move the pressurized low-pressure gradient stream to a flow-combining device. A second pump operates in parallel with the first pump and moves a pressurized solvent stream to the flow-combining device where the pressurized solvent stream combines with the low-pressure gradient stream to produce a high-pressure gradient stream. A second gradient proportioning valve can produce, from a second plurality of sources of solvent, a second low-pressure gradient stream, wherein the solvent stream moved by the second pump to the flow-combining device and combined with the other low-pressure gradient stream comprises the second low-pressure gradient stream.

Abstract: A liquid chromatography system includes a gradient proportioning valve in fluidic communication with sources of solvent. From the solvent sources, the gradient proportioning valve produces a low-pressure gradient stream. A first pump is in fluidic communication with the gradient proportioning valve to receive, pressurize, and move the pressurized low-pressure gradient stream to a flow-combining device. A second pump operates in parallel with the first pump and moves a pressurized solvent stream to the flow-combining device where the pressurized solvent stream combines with the low-pressure gradient stream to produce a high-pressure gradient stream. A second gradient proportioning valve can produce, from a second plurality of sources of solvent, a second low-pressure gradient stream, wherein the solvent stream moved by the second pump to the flow-combining device and combined with the other low-pressure gradient stream comprises the second low-pressure gradient stream.