Shimadzu GC-MS Potential Vacuum Leak

[Tasneem12]

Hello All,

I am facing a very troublesome leak issue but struggling to pinpoint the source of leak. The GC component is working fine, its holding carrier gas flow and gc column pressure fine. But when I try the auto startup, it does not trigger the rotary pump to start, neither does it start the turbo pump or the ion source. If I do it manually, the rotary pump pressure goes down to 2 Pa, then I turned the turbo pump on, the pressure went to 3e-4 Pa. Now here comes the issues:

1. There is bubble forming in the rotary pump oil viewing window.
2. The instrument passes the auto tuning
3. The ion source temp goes upto 230C which I can see in the software's window but GC panel shows the temp to be zero.
4. There is no loud noise coming from the turbo pump.
5. Since it passed the auto tuning, I tried collecting background scan, GC would start running but mass spec status stays at "Ready" but it doesn't collect any scan.


I suppose the bubbles forming would indicate a leak but I don't know where that could be coming from, I even tried using a Helium detector around the instrument and found nothing. Please let me know what steps I can take now. Thank you

[H.Thomas]

Hi Tasneem,

your vacuum readings seem ok, so there is probably no leak in the MS.

I don't know why the GC panel shows the wrong ion source temp, but as long as the software gets it correct this should not be a problem.

The turbo pump shouldn't make a loud noise - if it did, it was broken.

You should check your method if the instrument doesn't collect mass spectra. What are your start and stop times set on the MS-tab in the instrument parameters?

For the bubbling oil: open the gas ballast valve for an hour or so. If that doesn't help, change the oil.

Kind regards, Hartmut

[Tasneem12]

Thank you Hartmut.

I was wondering if there is any command i can provide to mass spec to start other than just starting the run? Our instrument is a hyphenated technique, it is connected with a py unit, normally the process starts from py and it triggers gcms start. Now that we are trying to troubleshoot it, we have separated the connection with py.

Now when i start a single run in gcms, gc starts but mass spec stays at "Ready" status like I mentioned in my previous message. Is there any way i can send "start" signal to mass spec? In my method mass spec is supposed to start after 1 minute. But it doesn't start at all.

My auto tuning results are fine and vacuum is also fine.