Discussions about GC-MS, LC-MS, LC-FTIR, and other "coupled" analytical techniques.

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What ionization method will be tried out first when one wants to do LC/MS analysis? Will it based on molecule polarity? Thanks.

Hi Jan,

I hardly strongly recomend you to see what's on structure: If there is a N in the structure and it's not to big (high molecular weight) I would begin with ESI in positive mode. :wink:

But it also depend in the HPLC mobil phase that you are using because some compounds could produce a bad spray with ESI........

More information will be usefull to help you.


Hi Jan,

I started by writing a long reply of all the factors that you need to consider but that is not what you asked. So...

Personally I start almost always with ESI except if I see that the molecule seems quite hydrophobic and without any chargable functional groups. If you have a molecule which response is the same with both ionisation techniques then I would go with APCI as it has been proven that you have less ion suppression from matrix interferences...


Ops a big mistake !!

I hardly recomend you to see what's on structure

It should said: I strongly recomend you to study the structure to decide the kind of ionization that you are going to use.....

I agree with Kostas reply....

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