Another Agilent 5973 air leak

[djletin]

I have developed another very significant air leak on 5973 MSD. Earlier problem was solved by putting new ferrule and interface nut on MSD end of column. Symptoms this time are that N2 is good (<5%) if set column head pressure hi (25 psi or greater). However at operating pressure (~12 psi @ 40oC or about 17 psi @ 105oC, N2 level is > 100% (relative to m/z 69). Column is 0.2 mm id, 30 m Length. Seems related to inlet. I've gone back and forth between merlin seal and regular spetum and change liner and replaced o-ring several times. Also replaced inlet end column nut and ferrule, all to no avail.

[lostcosmos]

Hi djletin,

A good tip for finding leaks on the MSD is to use a fluorocarbon spray a.k.a canned air (like Dust-Off). Check the label for the main component and start a manual tune and scan in the range of the base peak (usually 25 to 125 m/z is good). Spray around fittings allowing enough time for the compound to reach the detector. Watch the manual tune for peaks from your fluorocarbon spray. Don't forget to check the calibration vial and around the MS itself.

Hope this helps.

George

[Rick]

Isolate your injector...put a septum at the end of your column (injector side) and verify if leak is always present

[AICMM]

djletin,

Have you checked to make sure you have the compression washer that goes underneath the bottom plate of the injector. If this is on top or missing you can get a leak in the injector.

Best regards.

[Bigbear]

Are all your zones hot? I got a big leak just by cooling my transfer line.
Some times you can get an apparent leak if the split vent solenoid is open! Try setting your injector to splitless.