Ionization suppression in GC as well?

Chromatography Forum: GC Archives: Ionization suppression in GC as well?
Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Wednesday, March 3, 2004 - 07:27 am:

It is well know that coeluting cpds could cause ionization suppression in LC-MS. What about GC-MS (EI)? Could coeluting cpds cause ionization suppression in GC-EI MS?

TIA.

Jimmy


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Thursday, March 4, 2004 - 08:08 am:

Jimmy,

In my humble opinion I don't think this is a big concern. The amount of energy you are putting into the system at 70ev is fairly large and I doubt there would be anything much that could suppress ionization with these energies.

egards,
Mark


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Thursday, March 4, 2004 - 09:12 am:

You will see more of this effect in an ion trap than in a quadrupole system. This is the case when a trace component co-elutes with a major component and is related to the limited ion capacity of traps.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Friday, March 5, 2004 - 04:07 am:

If we use external ionization, the limited ion capacity of ion traps would not affect ionization. Therefore, ionization suppression won't occur with external ionization with GC-EI MS. Is this true? Please advise.

Too many ions in the trap will cause only poor linearity, resolution and mass shift. Is this true?

Thank you all for the reply!

Jimmy


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Tuesday, March 16, 2004 - 05:34 am:

Jimmy,
What you say about the traps are true, too many ions will cause a mass shift, nonlinearity and possible excessve ion-molecule reactions making the interpretation a real challenge. However, most of the modern traps no incorporate software which gates the ions into the trap automatically keeping the concentration in a workable range. (Just came back from PittCon and heard a multitude of sales pitches and specs and ....). Anyway the bottom line is the traps with external ionization seem to be getting more rugged and easier to use so don't be discouraged from looking into them further.

Regards,
Mark


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