Chromatography Forum

I am trying to analyze cyclohexane dicarboxylic acid by GC, using a polar column (HP-INNOWAX or similar), and am not seeing anything but injection front. I have tried MeOH, which gave a huge injection front, carbon disulfide, which is supposed to be transparent to FID (but still showed an injection front peak), and ammonium hydroxide as solvents, but all three gave injection front peaks (the latter two from stuff in the solvents), and no CHDA peak. Am I barking up the wrong tree here? My experience in GC is limited, so any help or guidance would be appreciated.

You are trying to chromatograph a di oic free acid by GC?

GOOD LUCK.

This species is not the most volatile. Without volatility the di acid just sits on the phase and giggles at you.

You must use a silylating reagent or make an di-ester from the free di-oic acid to make this species move down the column.

There are many methods to esterify free acids. If you don't have a book then do a quick search even on this forum to find methods that will be useful.

Good luck.

Rod

I may be new to GC, but some things just don't pass the sniff test. I pulled a paper last week showing an aniline derivitization where the chemist could look at dioic acids and some sugars by LC using a one-pot derivitization. Sounds like a good way for me to stop wasting time.

Thanks for your help!