Chromatography Forum

Does anyone have a good column or method suggestion to separate choline cation from the trimethylamine cation? I'm specifically looking for method to get residual TMA in a sample that has % levels of choline in it.

Thanks

I would do this on a silica column with HILIC. I see more of a problem with detection. What detectors do you have?

We developed a method for one of our customers for these compounds. I cannot share details but the following links will explain how you can use Primesep column for the analysis of tertiary and quaternary amines. You can use Primesep 200 with TFA in the mobile phase and ELSD detector (compounds have no UV activity). You will need to set up your ELSD at 30-35*C to obtain accurate results.
http://www.sielc.com/compound_086.html
http://www.sielc.com/compound_005.html
http://www.sielc.com/application_054.html

Regards,

Vlad

The Metrosep C 2 - 150 column will do the job with nonsuppressed conductivity detection. Standard eluent with 20% acetone.

What is all that secrecy? Trying to prevent people from finding out what they ingest or whatever?

What is all that secrecy? Trying to prevent people from finding out what they ingest or whatever?

There was absolutely no intention to create a secrecy.
The Metrosep C 2-150 column is Metrohm standard cation column (4.0 x 150 mm). The eluent could be 4 mmol/L tartaric acid/20% acetone.

I hope that helps.

I have not injected them together in a Dionex IonPac CS18 column, but trimethylamine and choline should both have good peak efficiencies and asymmetries on this column. Selectivity for the stationary phase will probably be different enough to resolve them well.
A simple low concentration acidic eluent should elute them well, probably not higher than 10 mM methanesulfonic acid should do it, followed by suppressed conductivity detection. If needed, try gradient elution for better resolution.

We have a CS18 column in our cations IC system that uses conductivity detection. I have some other HPLC systems but if this works then that would be easiest. Thanks to all for your help.

Markus, I was referring to "I can not share details....."

"I cannot share details" relates to the fact that we signed a Confidentiality Agrrement with this particular customer. I don't want to post something here to be later discovered as violation of the agreement. Links I provided give a good idea/indication on the approach.

Vlad