please help me

[emma2009]

Hi everyone,

I had a bad day today in our GC/MS lab. I was trying to fix a leak indicated by my routine water/air check. I thought it was the column that goes into the transfer line was not tightened... Then, I still do not know what I was thinking about, but I was stupid enough that I unscrewed the source nut and then I heard the noise of the foreline pump and saw some fume-like thing off the foreline pump and I then realized that i did not vent the MS!!! The foreline pressure went off the ceiling of course. I immediately turned off the foreline pump and did a "vent", waited for the diffusion pump to cool down and turned the whole system off.

I tightened everything, and restarted whole system. After 4hr waiting, I tried an autotune, the error was that like "signal too low to do an autotune ". I am wondering if the foreline pump is bad because the foreline pressure was showing "160 mTorr (pressure Ok)". I think normally it is shown below 50 mTorr. Or maybe the MS is bad due to my stupidity?

Can anyone here help me analyze this problem now? Please help !!! :lol:


Thanks a lot!

Emma :)

[Don_Hilton]

Step one: let the rough pump run over night - see if the fore line pressure comes down. And it will give you a break before you start into any other repairs.

If the ion source was on at the time... you may have damaged the filament that was on. So, if you have good enough vacuum to run, try switching filaments and see how things go.

Next thought is pull the source and see if hot parts were oxidized. And a source cleaning may not hurt - because that is about the end of the cheap and easy stuff.

If you had voltage on the detector, there is a chance that you damaged the detector.

Some ideas for you....

[emma2009]

Thank you for replying...

I will leave it over night,

then examine and clean the source... I was not using the MS at that time...I think it was not on...

So worst scenario, if the detector is damaged, which part should I replace? The detector seems to have a lot of parts in it.... How do you tell if the detector "has voltage on it "? Does that just mean that it is not vented or does that mean it is ON...

Thanks a lot!

[Don_Hilton]

You have not stated what kind of instrument you are using - so I can not give you details for the detector. And, if you tell what kind of instrument you are using, someone who uses that kind of instrument may be able to give you more specific advice.


A detector has voltage on it when you are acquiring data. But, like the type of detector, voltage on the detector between GC rund depends on the manufacturer.

[emma2009]

I am using 5972 HP.

Now everything is back to normal now, thank God!

After I tuned it, the actual temperature is not shown on the method and it shows "not ready" with the red light on.

This is a general question: when it shows "not ready," what would be wrong?

Thanks a lot! I love this forum and I hope to be able to help someone too!

[Don_Hilton]

Without a '72 user jumping in I'll try to give you a couple of ideas. (It has been about 8 years since I've run a '72 - or other Agilent MS.) The lack of temperature reading indicates a problem with the temperature sensor or associated circuitry. Not ready is an indication that the computer can not confirm that the instrument is ready to run. If this is the transfer line temperature, it is a GC issue or communication issue. That may be fixed by restarting the GC. (Make sure the power connector for the transfer line is connected.)

Some things to check as we wait for someone more current with the '72 to post.