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- Posts: 10
- Joined: Mon Aug 13, 2007 2:56 pm
Hope somebody can help here. I'll try and be brief but specific..
Have a 15 year old HP5972 interfaced with a HP5890 II GC and Tekmar 3100/Solatek 72 concentrator. Here is the problem:
-High baseline, around 40000 counts. It's still there when I direct inject a run and look at the chromoatography, so the problem is not Tekmar related.
-Loss of sensitivity and gradual increase in EMV over a week period. I'm currently running a 6:1 split with a Agilent DB624 20m .25mmID 1.12 um thickness column. Purge Valve is constantly "on". Septum purge vent in the front of GC is not capped.
-I do get peaks. The problem seems to be excessive baseline noise which is interfering with some of the compounds, like the ketones.
-MSD was recently refurbed. New motherboard and quads. Problem was eveident before this and remained upon completion of refurb
-We had previously split sample through a jet separator and before this problem, had changed over to splitting through injection port. The split vent line was cleaned.
-No "noticable" leaks around system using a helium sniffer.
-Manual tunes look good. Only issue is that over a week period, have to raise the EMV
-Background ions are 41, 55,69, etc. So it has a hydrocarbon 14 amu pattern, although library search tags it as "HAHNFETT". There has not been any stopcock grease added.
-running constant flow (have tried anything from .5-1.0ml/min) and injection port temp is 210, interface temp is 225, source temp reads 145. i have good foreline pressure (33 mTorr) as well.
-Everybody, including an Agilent service engineer is stumped on this one. if you need further info, I can provide it. Thanks for any help offered.
P.S New liner, septa, gold seal installed recently. Column is 4 months old, interface nut is the Restek conversion fitting. I'm "suspicious" of some of the valves in the GC as we hadn't been plumbed to run this way for 14 of the 15 years we've had the system. The sample always ran from the Tekmar transfer line to the column, to the jet, then through a piece of transfer line to the MSD. The injection port was disabled.
Have a 15 year old HP5972 interfaced with a HP5890 II GC and Tekmar 3100/Solatek 72 concentrator. Here is the problem:
-High baseline, around 40000 counts. It's still there when I direct inject a run and look at the chromoatography, so the problem is not Tekmar related.
-Loss of sensitivity and gradual increase in EMV over a week period. I'm currently running a 6:1 split with a Agilent DB624 20m .25mmID 1.12 um thickness column. Purge Valve is constantly "on". Septum purge vent in the front of GC is not capped.
-I do get peaks. The problem seems to be excessive baseline noise which is interfering with some of the compounds, like the ketones.
-MSD was recently refurbed. New motherboard and quads. Problem was eveident before this and remained upon completion of refurb
-We had previously split sample through a jet separator and before this problem, had changed over to splitting through injection port. The split vent line was cleaned.
-No "noticable" leaks around system using a helium sniffer.
-Manual tunes look good. Only issue is that over a week period, have to raise the EMV
-Background ions are 41, 55,69, etc. So it has a hydrocarbon 14 amu pattern, although library search tags it as "HAHNFETT". There has not been any stopcock grease added.
-running constant flow (have tried anything from .5-1.0ml/min) and injection port temp is 210, interface temp is 225, source temp reads 145. i have good foreline pressure (33 mTorr) as well.
-Everybody, including an Agilent service engineer is stumped on this one. if you need further info, I can provide it. Thanks for any help offered.
P.S New liner, septa, gold seal installed recently. Column is 4 months old, interface nut is the Restek conversion fitting. I'm "suspicious" of some of the valves in the GC as we hadn't been plumbed to run this way for 14 of the 15 years we've had the system. The sample always ran from the Tekmar transfer line to the column, to the jet, then through a piece of transfer line to the MSD. The injection port was disabled.
