Possible GC/MS electronical problems

[ishkaw]

Hi all,

I am working with a GC/MS Agilent 6890-5973 and I have problems with the optimisation of the repeller and the entrance lens in the manual tuning (problem occured after source maintenance). I can't get the Gaussian shape that I should have normally (see picture below).


This problem also occurs in the atune.u mode although the Tune report is fine (parameters are ok, abundances are ok...). I would have started my analysis if it wasn't that I was in front of the screen when the tune was running and I saw quickly that the repeller did not give a Gaussian shape..

I tried cleaning and reinstalling the source and got similar results... By the way, all the wires are connected to the right places and there are no loose connections. I changed the repeller, the insulators, the draw-out plate and even the electron multiplier (because it was overdue) and not of it worked...

I switched the source of the 5973 with the one in my other GC/MS (5975) and got good results on the second GC/MS (and bad results with the good source on the malfunctioning GC/MS). So, the problem is not the source itself.

I though that it might be a corrupted file so, after rebooting my entire system, I loaded a previous tune, saved it under a different name and ran it and still got bad results. Now, the only option I see is that this is an electronic problem. Maybe it could be the ceramic board on which the wires are connected, I've heard that sometimes it fails but I don't know what it does exactly when it's broken...

Does anybody have any idea what is the problem or what could I do next?

Thanks!

[cleh]

Try re-setting the atune file to defaults, save that and then run your autotune.

[ishkaw]

Try re-setting the atune file to defaults, save that and then run your autotune.

How do I reset to defaults? Is there any place or any buttons in chemstation that could do it automatically? I though that using a previous tune that worked and running it was a kind of re-setting...

thanks

[cleh]

It's in the tune section. I believe it's under load tune. It should say reset to defaults. Using an old tune file usually works, but I've had times when that didn't work but resetting the defaults has.

[ishkaw]

It's in the tune section. I believe it's under load tune. It should say reset to defaults. Using an old tune file usually works, but I've had times when that didn't work but resetting the defaults has.

Thanks for answering so fast but I couldn't find anything that looks like Reset to defaults when I load tune parameters.... I have to add that I tried other kind of Tunes (Lomass, Stune) and got the same bad results. I don't usually run those tuning so I'm pretty sure that they are not corrupted. I think that would eliminate the corrupted file option...

Any other idea of what could be my problem?

Thanks

[ishkaw]

I found how to restore tune parameters to default. I typed FRESHTUNE in the command line and it got back to default. I ran an atune again and get the same bad results
Please help me someone!!

Thanks

[Rick]

Hi!
It's important to isolate your problem...so,
1- cap your interface and test your msd only, with no column connected to your msd.
2- verifiy your vacuum with ion gauge
3- Have you redipped your quad?

[cleh]

You have already verified that the source is good by installing it another MS and getting the good tunes and installing the other instrument's source in this MS and getting bad tunes. Now you know it's not a corrupt tune file. Please post you're air/H2O check and a profile and scan of you're manual tune (69,219,502).

[Bigbear]

We still have not ruled out a corrupt tune file.
Please do the following:
open msdchem\1\5973 or 5975 or 5973N folder ( the instrument you use) There will be xxx.u file ( example autotune.u) Left mouse click on it to highlight then right click to rename it autotune.old
Then go to mschem\mssetup\5973 or 5975 or 5973N folder ( the instrument you use) youwill see autune.pu and autotune.nu ( pu= + polarity and nu= -polarity). Copy the one you need and paste into msdchem\1\5973 or 5975 or 5973N folder Left mouse click on it to highlight then right click to rename it autotune.u

This will give you a factory fresh tune.

[ishkaw]

Hi!
It's important to isolate your problem...so,
1- cap your interface and test your msd only, with no column connected to your msd.
2- verifiy your vacuum with ion gauge
3- Have you redipped your quad?

Hello and thanks for the reply it helped, I tested the msd only, the vacuum is good and everything is fine when I do a manual tune, no more random peak shape!

I plugged another column (the one on the back injector) and got the same bad results... By the way, I forgot to mention that I am working with an EZ-NoVent transfert line. Next step I'm going to do is remove it and plug the column directly in the MSD. Hopefully it will resolve the problem!

I don't know anything about redipping the quad, can you tell me more about that please? How to do it and when it is needed to be done?

Thanks

[ishkaw]

You have already verified that the source is good by installing it another MS and getting the good tunes and installing the other instrument's source in this MS and getting bad tunes. Now you know it's not a corrupt tune file. Please post you're air/H2O check and a profile and scan of you're manual tune (69,219,502).

Hello and thanks for the help, here are the air/H2O check and the manual tune

[Rick]

Hi!
You have a air leak....correct it.
Dipping RF coil procedure can be found in the 5973A/N hardware manual.

[cleh]

Hello and thanks for the help, here are the air/H2O check and the manual tune

Air/H2O and peak shape look good. If you find bypassing the EZ no vent works out by installing the column directly, it may be a cracked or broken transferline on the EZ no vent or it may be inserted too far into the MS source. Great trouble shooting technique!

[MSCHemist]

I plugged another column (the one on the back injector) and got the same bad results... By the way, I forgot to mention that I am working with an EZ-NoVent transfert line. Next step I'm going to do is remove it and plug the column directly in the MSD. Hopefully it will resolve the problem!
Thanks

Oh I've been interested in asking how do you like the No-Vent system. I work with the Agilent Quickswap and found it to be a nightmare to get to form a seal on the transferline. Does the Restek system work well. I am getting a 6890/5973 for the plant and thought it might be a nice add on.

[remaou]

Hi ishkaw. Have you solved your problem ?
I'm in the same situation...
thanks