Formic acid and acetic acid analysis

[annabegna]

Hi to everybody,
I need your help with the Formic and Acetic Acid analysis on glycols.
I tried in GC\FID with a supelcowax 10, following an agilent application (see the link ) note for a HP-innoWAX (cross linked PEG)
https://uqu.edu.sa/files2/tiny_mce/plug ... ations.pdf

Something comes out about acetic acid but nothing about formic acid (honestly even the application notes weren't speaking about it)
How can i analyse these free organic acid in such a difficult matrix?
I can try by hplc/uv with a proper hplc column but i'm afraid about glycols interaction with the mobil phase (acid water), with atlantis dc10 column for organic acid, and all hplc system.

Honestly i'm a young technician, with poor experience...please help me!

Annamaria

[Peter Apps]

Welcome Annamaria

Formic acid contains so little carbon and oxygen that it is nearly invisible to an FID. If you want to do it as the free acid you will need an MS and a very well deactivated system.

Your best approach will probably be to derivatize it - we have some regulars here with a lot of experience in that area.

Peter

[AICMM]

Annamaria,

Conveniently not speaking to the chromatography, and seconding what Peter had to say about detection, the FID will work quite poorly. I have seen these analytes methanized to become detectable by FID so if you have access to that it would help you work significantly I think. You can't improve the chromatography of that you cannot see.

You could use argon ionization as well but that is a subject for another day.....

Best regards,

AICMM

[Consumer Products Guy]

HPLC with conductivity detector with organic acid column.

[MSCHemist]

Capillary electorphoresis is good for organic acids and other anions as well. Acetic I make into isobutyl acetate using isobutyl chloroformate, extract with hexanes, and do on a db-5 or 1. Formic I haven't tried but it probably would be covered up by pyridine from the reaction mix though you could use picoline instead and both acetic and formic might come out before it.