Cannot get rid of water in source chamber on qtof 7250

Cannot get rid of water in source chamber on qtof 7250. Helium checked and is free of water. I think only helium gas flows into MS. What could be going on? right now it's at 30% water vs ion 69.

I sprayed all over with duster looking for leaks. I would expect any leaks to result in high oxygen as well as water, however, oxygen is at acceptable levels. and no leaks detected.

tuning is not acceptable. not sure if this is related to water or it is another issue. not enough resolution for ion 502.

Scheduled agilent tech to come in but who knows how soon they can come.

0 howard_sanford over 1 year ago

Hi ChicagoCarbs ,

I've moved this to GC/MS Hardware for better visibility.
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0 paulsalverda over 1 year ago

If there's no water coming in from the gases, the water inside a GCMS after it has been opened for maintenance and then pumped back down is gone in <8 hours in a single/triple quad and a 7250 that was running properly before.

Collision Gas on 7250 (Different from 7200!)
Helium: 4 mL/min N2: 1 mL/min
The collision gas (or at least N2) can be turned off to maximize relative abundance of the molecular ion. Turning off N2 gas will not affect the sensitivity but it will affect your capability of performing MS/MS. Use He at 5 mL/min in this case. Turning off both He and N2 will significantly affect the sensitivity.

It is necessary to perform autotune after turning the collision gas off and wait at least 30 min before proceeding with tuning.

What is your column flow rate? The HES spectral tilt changes with flow - so higher than ~1.4 ml/min of column flow can make it look like there's an air leak.

Is there any N2:O2 ? Just high water is unusual.... What are the vacuum readings? The pump wattages?
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