Chromatography Forum

I need to quantify amino acids in plasma, currently Proline only. Is ion pairing the best option ?
I've tried HILIC with Amm formate or acetate/ACN but did not work. I have little bit experience with hypercarb (phosphorylated nucleosides) but had issues with reproducibility.
I'm thinking of trying HFBA or TFA, any suggestions welcome, please.
Can I use a regular C18 column with ion pairing as long as it has the pH range ?
Thanks

I do GC/MS and for just proline FID is fine. I do ethyl chloroformate derivatization as per Husek with norvaline ITSD. Phenomenex sells a kit EZFAAST that uses a proprietary GC column phase and n-propyl chloroformate. All amino acids except arginine work though that might soon change with this new article once I get my hands on it and some methylglyoxal. Proline works very well you can achieve very high sensitivity (ppb range).

https://www.researchgate.net/publicatio ... ng_Reagent

If access to GC-MS is an issue, SCX followed by AccQ derivatization and LC-MS/MS. Using isotopically labeled AA will get you ultimate metrics.

Thanks for your valuable suggestions, will consider when I need to all aa in one run.
Got proline on amide column with HILIC mode with varying buffer conc.