Hi everyone.

My lab has taken over a hugely problematic Varian GC-MS, and have been having serious issues.

First, the nitrogen tank was going down ridiculously fast, but we were unable to find a leak. Around this time we developed very high water peaks while running the daily diagnostic checks.

When we changed the N tank, the water peak stayed but the levels stopped tanking and returned to a normal level, so I figured it was a faulty tank or regulator connection causing the loss of gas.

After this situation was resolved, we had to shut down the GC-MS a few times in order to cover it for construction in the instrumentation room.

After the 3rd bakeout, we ran an autotune, which failed. The error was that the Trap Frequency Calibration failed. This was almost a month ago and all the software diagnostics come out fine. Further, the MS is unable to detect two different Cal Gas Ions that we should be seeing.

And now this past weekend, the Helium tank has been depleting the way the Nitrogen was before. The only thing we changed right before this occurred was changing out the N tank, which should not have disrupted the He in any way.

So, we are fairly certain that there is a leak somewhere. We have been using compressed air and an electronic leak detector to search, and have come up with nothing around the column, the oven or any of the usual ports.

What we are going to try next is to cap the MS separate from the GC and see if the pressures are off in either to try to isolate the leak. However, the pressures have been fine this entire time. The only indication of a leak was the tank depletion.

We don't know if the autotune failure and the missing cal gas ions are caused by a leak or not.

I was wondering if anyone here had any insight into what may be going on here, with the trap frequency calibration failure or the missing cal gas ions?

Also, any advice on how to find this leak, preferably without calling in a technician?

I would appreciate any help anyone is willing to give, I'm at my wit's end here.