[MEAS]

Hi I'm a graduate student with a GCMS with extremely high air/water checks causing the instrument to be inoperative.  Both the column and the MS have been baked out and still have high air/water checks.  Based off our troubleshooting guide, we've narrowed the issue down to a water leak in the MS.  There is no contamination from/in our gas cylinder since it has not been bothered with in the last few weeks.  Potential issues could be the o-ring however the guide did not clarify which o-ring in the instrument. 

Has anyone run into this issue before and know which o-ring needs to be replaced? Or has anyone had to deal with high air/water checks before? Is this a common issue?

Lastly, the instrument of question is an Agilent 210-MS GCMS.

Thank you for any helpful suggestions!

[marquis]

Agilent has some pretty good online app notes, as well as phone troubleshooting.  I'd try that first.

I'm used to the older agilent instruments.  Please confirm that the leak is showing up as high pressure in your vacuum line.  If so, the most common source of air leaks with the older GC/MS is the ferrule around the columns.  If they are just a little off, your vacuum goes to heck. 

If it is water, then your best place to look is at the drying media in your helium line.  Of course, your vacuum line or vacuum pump can also cause problems, especially if the instrument hasn't been used for a while. 

Good luck.

[marquis]

Sorry, forgot to mention.

Check the septum (if you are using one) at your injector.  The septumless injectors were very good a didn't leak until after 5000 or so injections.  But the rubber septum ones could start leaking quickly.