How to Configure the Optimum Delay Volume

The design of the Flexible Pump offers a strongly decreased delay volume compared to standard 600 bar pressure pumps. For the Flexible Pump, mixing is done in the multi-channel gradient valve at ambient pressure. As all pump parts in the flow path after mixing contribute to the delay volume, this also includes pump heads, flow connections, filters, mixers etc. Therefore the delay volume of a quaternary pump (Flexible Pump) is by design larger than that of a binary pump.

All listed components including the inlet weaver and pump heads ensure a good mixing performance resulting in excellent composition precision, and accuracy, highly reproducible retention times, and low baseline noise. This ensures best results for most applications.

Per default, the Flexible Pump does not require and include a Jet Weaver, as solvents are mixed in the MCGV and mixing is further improved in the inlet weaver, pump heads and subsequent parts in the flow path. Therefore, no Jet Weaver is required for most applications.

Jet Weaver high-performance mixers are optionally available for demanding applications, which use solvents in different channels. For example, A versus B solvents, which differ strongly in their UV-Vis absorption, e.g. using trifluoroacetic acid (TFA) as a modifier, which has a high absorbance. Solvent packages created by the pump may persist until the solvent reaches the detector flow cell. Absorption fluctuations can then show up as baseline noise, also referred to as mixing noise. Applications like impurity quantitation or lowest level compound detection require minimizing this noise. Jet Weavers strongly improve mixing and therefore reduce baseline noise and improve sensitivity in detection. Patented Agilent microfluidic technology offers high mixing performance at a low internal volume. For example, the physical volume of all channels for a 380 µL mixer only contributes with 150 µL to the pump delay volume (< 350 µL without Jet Weaver), which is the partial mixer volume that creates a composition change corresponding to the delay volume.

The installation procedure is illustrated in Install the Jet Weaver.

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