The invention provides methods for quantifying a non-ionic surfactant in a composition comprising a polypeptide and the non-ionic surfactant, where the quantification exhibits reduced interference between the non-ionic surfactant and the polypeptide. Also provided are methods where the composition further includes N-acetyl tryptophan, and the quantification exhibits reduced interference between the non-ionic surfactant, the polypeptide, and N-acetyl tryptophan.

The invention provides methods for quantifying a non-ionic surfactant in a composition comprising a polypeptide and the non-ionic surfactant, where the quantification exhibits reduced interference between the non-ionic surfactant and the polypeptide. Also provided are methods where the composition further includes N-acetyl tryptophan, and the quantification exhibits reduced interference between the non-ionic surfactant, the polypeptide, and N-acetyl tryptophan.

A pressure system for liquid chromatography allows multiple fluid lines to be driven in parallel by a single pump. A fluid pressure medium supply provides fluid pressure to the system. The fluid pressure medium supply is connected to a plurality of fluid transfer pipes, each with a flow limiter. The fluid pressure medium supply is configured to provided more flow than the flow limiters combined, and excess flow is either diverted with a pressure limiter or reduced with a pressure adjuster, or both. Further layers of pressure and flow control may be added with additional pressure limiters and/or pressure adjusters and flow limiters connected together. In some cases, multiple lines containing different fluids may be driven by the same pressure source through the use of flexible fluid delivery inner containers, each within a rigid container that is pressurized by the pressure source.

A pressure system for liquid chromatography allows multiple fluid lines to be driven in parallel by a single pump. A fluid pressure medium supply provides fluid pressure to the system. The fluid pressure medium supply is connected to a plurality of fluid transfer pipes, each with a flow limiter. The fluid pressure medium supply is configured to provided more flow than the flow limiters combined, and excess flow is either diverted with a pressure limiter or reduced with a pressure adjuster, or both. Further layers of pressure and flow control may be added with additional pressure limiters and/or pressure adjusters and flow limiters connected together. In some cases, multiple lines containing different fluids may be driven by the same pressure source through the use of flexible fluid delivery inner containers, each within a rigid container that is pressurized by the pressure source.

A method of introducing a sample into a separation column includes introducing the sample into a trap column, isolating the trap column from ambient atmosphere and pressurizing the trap column to a first pressure while the trap column is isolated from ambient atmosphere, providing a fluid connection between the trap column and the separation column after pressurizing the trap column to the first pressure, supplying the sample from the trap column to the separation column.

A method of introducing a sample into a separation column includes introducing the sample into a trap column, isolating the trap column from ambient atmosphere and pressurizing the trap column to a first pressure while the trap column is isolated from ambient atmosphere, providing a fluid connection between the trap column and the separation column after pressurizing the trap column to the first pressure, supplying the sample from the trap column to the separation column.

A fluid supply device for providing a mobile phase for a sample separating device includes, a supply conduit for providing a fluid which forms at least a part of the mobile phase, a fluid valve which is fluidically coupled with the supply conduit and, depending on its switching state, enables or prevents a passing of the fluid from the supply conduit, an elastic buffer unit which is fluidically coupled upstream of the fluid valve with the supply conduit and which is configured for buffering the fluid, and a fluid conveying unit for conveying the fluid which passes the fluid valve.

A fluid supply device for providing a mobile phase for a sample separating device includes, a supply conduit for providing a fluid which forms at least a part of the mobile phase, a fluid valve which is fluidically coupled with the supply conduit and, depending on its switching state, enables or prevents a passing of the fluid from the supply conduit, an elastic buffer unit which is fluidically coupled upstream of the fluid valve with the supply conduit and which is configured for buffering the fluid, and a fluid conveying unit for conveying the fluid which passes the fluid valve.

Exemplary embodiments are directed to a rotary selector valve that includes a valve body that includes a rotor and a stator. The stator includes a first port for flow of a first flow material and a second port for flow of a second flow material. The rotor includes a groove for flow of at least one of the first flow material and the second flow material. The rotor includes a vent groove disposed between the first port and the second port for venting at least a portion of at least one of the first flow material and the second flow material to an exterior of the valve body. Exemplary methods of operating a rotary selector valve and CO2-based chromatography flow systems including a rotary selector valve are also provided.

Exemplary embodiments are directed to a rotary selector valve that includes a valve body that includes a rotor and a stator. The stator includes a first port for flow of a first flow material and a second port for flow of a second flow material. The rotor includes a groove for flow of at least one of the first flow material and the second flow material. The rotor includes a vent groove disposed between the first port and the second port for venting at least a portion of at least one of the first flow material and the second flow material to an exterior of the valve body. Exemplary methods of operating a rotary selector valve and CO2-based chromatography flow systems including a rotary selector valve are also provided.