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High N2 reading from air/water check GC-MS. Leak is coming from inlet. How to fix? How to troubleshoot?

Question asked by chemist23 on Aug 14, 2019
Latest reply on Sep 11, 2019 by chemist23


I am having trouble with getting the air/water check to pass on GC-MS.

I was able to determine that the issue is coming from the back inlet by plugging the inlet side of the column and also testing out the air and water check readings when connected to the front inlet.

So far I have tried , changing septum, liner, o-ring, gold seal but I am still getting a relatively high N2 reading.

For reference this is what my air and water check looks like:

Water: 3.01%
Nitrogen: 21.06%
Oxygen: 6.39%
Carbon dioxide: 0.29%

The N2 readings usually fluctuates between 12 and 21%.

Any more steps I should take to correct the back inlet? I am using a split/splitless inlet connected to a headspace sampler.