What are the suggested time intervals when using a diverter valve?

For research use only. Not for use in diagnostic procedures.

Answer

Efficient use of diverter valve will keep the mass spectrometer source and ion optics from unnecessary and excessive contamination. This article provides guidance on how to set an appropriate time range for use of a diverter valve during an acquisition method.

SCIEX mass spectrometers (MS) such as the Triple Quad™ 4500, 5500 and 6500 systems are equipped with a built-in diverter valve. The API™ 4000 and 5000 systems and some TripleTOF® systems do not have a built-in diverter valve; however, an external diverter valve can be added.

Note: The numbers used in this article refer to a method use for small molecule analysis with reversed phase chromatography. Usually in such methods, the peaks are about 0.1–0.15 min wide, and the retention time is stable, not shifting more than 0.2 min.

At time of injection (t = 0), the diverter valve should be set to waste, so that buffer salts that were not retained by the column do not enter the instrument. At ~0.5–0.6 min prior to the elution of the first peak, the diverter valve should switch to the MS, directing flow to the source; the source should be at a stable temperature before the first analyte elutes.

At the end of the method run time, at ~0.4–0.5 min after the last peak has eluted, the diverter valve should switch back to waste. This will allow for capture of any peaks that have right-shifted and also provides enough baseline to the right of the last peak for integration purposes. Diverting the flow during the later part of the gradient will prevent the very hydrophobic components from contaminating the MS. If the acquisition method retention times tend to vary ± 0.2 min, remember to adjust the divert valve settings accordingly.

See article below for more details of how diverter valve works and how to set it up: https://sciex.com/support/knowledge-base-articles/setup-of-diverter-valve_en_us