The physical delay volume of the pump depends primarily on the use of the Jet Weaver mixer. For UV detection, the Jet Weaver should always be used but for mass spectrometric detection the user can decide to bypass the Jet Weaver to reduce the delay volume. This only makes sense for ultrafast gradient operation (less than 0.5 min) or for use with very small volume columns. If the Jet Weaver is bypassed, the connection tubing to the autosampler is routed directly from the purge valve.
NOTE
Before disconnecting a Jet Weaver from the flow path, flush it with organic solvent (50 % isopropanol in water). Avoid leaving water or buffers inside the Jet Weaver, which may cause the growth of micro-organisms like algae or bacteria.
Sometimes it may be advisable to increase the delay volume in the pump. Specifically this can be the case when UV detection is employed and a strongly UV-absorbing compound has been added to the mobile phase. This can have the effect of emphasizing any pump noise and the most common example is the use of trifluoroacetic acid (TFA) in the analysis of proteins and peptides. The effect can be mitigated by increasing the mixer volume.
The following different Jet Weaver configurations are available:
The Jet Weaver (G7120-68135 (Jet Weaver 35 μL/100 μL) or G7132-68135 (Jet Weaver 35 µL/100 µL biocompatible) ) has two alternative volumes in the same unit.
The switch from the lower volume, 35 µL, to the higher volume, 100 µL, is done by uninstalling it, turning it around from front to back and re-installing it, see Change Configuration or Replace the Jet Weaver. The delay volume increases by approximately 31 µL and the baseline performance with additives like TFA improves. The configuration of the Jet Weaver is logged automatically by an attached RFID tag.
The 380 µL Jet Weaver high-performance mixer (G7120-68380 (Jet Weaver 380 μL) or G7132-68380 (Jet Weaver 380 µL biocompatible) ) is optionally available for demanding applications, which use solvents in different channels (for example A versus B), that differ strongly in their UV-Vis absorption. For example, it can be installed when 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. The 380 µL Jet Weaver strongly improves mixing and therefore reduces baseline noise and improves sensitivity in detection. Patented Agilent microfluidic technology offers high mixing performance at a low internal volume of 380 µL.
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id: 4289085195