N2 supply to Agilent LCMSMS

[meh1]

Hi,
I'm trying to make my nitrogen supply last as long as possible for the rest of the lab until our liquid nitrogen is delivered tomorrow, so I would like to shut off the supply to my lcmsms (Agilent 6490). Should I just shut off the N2 supply or should I vent the MS and turn it off completely? We will have adequate nitrogen in less than 24 hours. Any thoughts?

Many thanks,
M

[nbik]

Dear meh1,
usually for tof system you need to use two N2 supplies, one for collision cell and another for drying gas. Nitrogen supply for collision cell you can shut off when you want. If you want to close another supply then it will be safety to vent system - without drying gas your system can suck in air with some dust to your vacuum system. It will not be very good. Also you have heater in your ESI and ion optic, i'm not sure it works good without drying gas.

[michellec]

Technically, you can. As long as you let N2 gas flow for a while before your next experiment, you should be fine assuming that

1. there will be no power failure, during which the MS needs N2 gas to vent the instrument.
2. the plumbing line for N2 was set up properly with no leak.

water vapor is a big problem for any vacuum system.