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Shimadzu GC-MS QP2010 Plus
Posted: Fri Apr 23, 2010 9:13 am
by Irina
Hi,
Is everyone using this GC-MS? I would like to know more about maintenance at it. Mine seems to have a bigger LOD that he used to with the same method and standards ( I'm doing VOC's on it, but I try to do something else on the same column and I'm not sure if the column is dead or I need to clean something else)
I changed the septa, the liner, I cleaned the ion source, but still had only a few very small peaks at a high concentration (1.6 mg/l)
Any advices are welcome!
Thank you
Posted: Fri Apr 23, 2010 9:39 am
by Irina
One more question. if my split is only a number and I set it like 30 what that's mean?
Thank you
Posted: Fri Apr 23, 2010 1:26 pm
by Ron
What is the column, and what did you inject? What is the detector voltage after tuning?
Posted: Fri Apr 23, 2010 5:10 pm
by Irina
What is the column, and what did you inject? What is the detector voltage after tuning?
column is alltech AT 502.2 and I had some toluene diisocyanate sample and i didn't had another column to analyse them. the voltage after tuning is 1.01
Posted: Fri Apr 30, 2010 11:54 am
by BZK
One more question. if my split is only a number and I set it like 30 what that's mean?
Thank you
The number of split (or better split ratio) set to 30 means that if you inject a solution containing 30 ng into GC only one reach the column inlet. The rest is splitting out. This is in theory and with a very large liner. Difference on temperature profile of the injector, large difference into molecule voltilities and injection wave pressure could introduce difference on split ratio and the split ratio could be not the same between low and high boiling compounds (discrimination).
Posted: Sun May 02, 2010 7:24 pm
by Irina
One more question. if my split is only a number and I set it like 30 what that's mean?
Thank you
The number of split (or better split ratio) set to 30 means that if you inject a solution containing 30 ng into GC only one reach the column inlet. The rest is splitting out. This is in theory and with a very large liner. Difference on temperature profile of the injector, large difference into molecule voltilities and injection wave pressure could introduce difference on split ratio and the split ratio could be not the same between low and high boiling compounds (discrimination).
thank you
Posted: Mon May 03, 2010 6:34 am
by bhuvfe
What are your analytes?
Do you see an increase of LOD for all of them or only for some of them?
I was wondering if the TDI you injected might have something to do with
your problem.
Posted: Mon May 03, 2010 12:58 pm
by Irina
What are your analytes?
Do you see an increase of LOD for all of them or only for some of them?
I was wondering if the TDI you injected might have something to do with
your problem.
All of them
Posted: Mon May 03, 2010 7:54 pm
by bhuvfe
I think that cutting 30-50 cm of your column might improve the situation.
Posted: Tue May 04, 2010 5:29 am
by bhuvfe
Besides a LOD increase do you see a loss of resolution (broader peaks, etc.)?
Posted: Tue May 04, 2010 11:01 am
by Irina
Besides a LOD increase do you see a loss of resolution (broader peaks, etc.)?
no, only a few more "bleeding" peaks. I think the column is dying
Posted: Tue May 04, 2010 11:40 am
by bhuvfe
Besides a LOD increase do you see a loss of resolution (broader peaks, etc.)?
no, only a few more "bleeding" peaks. I think the column is dying
If you are lucky only the first meters are dying..
help
Posted: Tue Nov 02, 2010 10:08 am
by Irina
one more problem with my MS. When I try to do the autotunning I have an error and it can't be done.The error is : "Mass calibration error".
I cleaned up the ion source , but the problem persist.
Any thoughts ?
thanks