Dear All,

I am a new user of LCMS. We have a Tandem MS hooked up with an HPLC system. We do not use a nitrogen generator. We use a huge liquid nitrogen tank as source for generating the nitrogen for the system. We also have an air compressor attached to it. My question is if we are to shutdown the system for general maintenance for a day or two (like say, weekends or long holidays), is it okay if we leave the nitrogen tank running while the LCMS and the air compressor are both turned off? Should I turn off the nitrogen tank as well?

Sometimes we have power shortages too in our area and I worry that if there is power failure that would take days, then the whole system (HPLC, Mass Spectrometer, and air compressor) will be off but with the nitrogen still in running. Will the continuous running of the nitrogen adversely affect my Mass Spectrometer? What should I do?

I hope you can give me advice on this. The MS is very expensive and I want to handle things properly.

Thanks

You should probably ask the instrument manufacturer as some of these things might be instrument specific. That being said...

If your instrument vents to atmosphere, either due to intentional shutdown or power failure, I don't think it would be harmful to have nitrogen flowing to the source. In fact, it is probably a good thing. Most LC/MS instruments vent through the sampling orifice, and this way you are venting your instrument with clean, dry nitrogen. But if your gases are entirely controlled by the instrument's electronics, then I'm pretty sure the internal valves will turn off the gases when the power fails, making it a moot point.

The power failures themselves are more likely to damage your instrument, especially if the power doesn't fail "cleanly". For example, it might flicker on and off, sag or brownout, or one phase might go out while the other phase remains on. To protect against these events, you may want to investigate buying a UPS. If you are present when the power fails, the UPS will give you time to properly shut down your instrument. If you aren't present, the UPS will cleanly cut power to your instrument when the battery runs out.

Thank you MG for your advice.