Shimadzu GC-MS QP2010 Plus

[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

[Irina]

One more question. if my split is only a number and I set it like 30 what that's mean?

Thank you

[Ron]

What is the column, and what did you inject? What is the detector voltage after tuning?

[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

[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).

[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

[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.

[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

[bhuvfe]

I think that cutting 30-50 cm of your column might improve the situation.

[bhuvfe]

Besides a LOD increase do you see a loss of resolution (broader peaks, etc.)?

[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

[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..

[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