DB-5 column for acetic acid and water mixture

[njoshi]

I am trying to analyze acetic acid in water using DB-5 column in Shimadzu GC-14B. my temperature program is 75 deg C for 6 min and 20 deg C/min to 150 deg C for 1 min.

the peaks I got has overlapping of rear of water peak with front of acetic acid . is there better way to separate the peaks?

I have been reading that mole sieve will work better.

any suggestion?

Narendra Joshi

[chromatographer1]

Where have you read that mole sieve works for that application? I would enjoy reading the article.

My suggestion is a Nukol capillary if capillary is required.

Expect with an aqueous solution of acetic acid that you may get inconsistent results due to the ionization equilibrium. You will also have issues with active sites in your injector as well as dangers of producing too large a vapor cloud of sample when you inject.

best wishes,

Rod

[njoshi]

Thanks Rod. it is helpful.

I meant Carbowax 20M not mole sieve. sorry about the mixup.

Narendra Joshi

[chromatographer1]

A Nukol, or even better, a SPB-1000 is based on Carbowax 20M but is chemically modified to improve the peak shape and recovery for acids.

C-wax 20M has too basic a character for best performance but will do in a pinch.

However, having an aqueous solution still entails the risks I previously mentioned.

Be careful and good luck,

Rod

[gcguy]

If you use THF as the solvent the peak shape for acetic acid on a DB624 is ok. Any other solvent then it is not so good.

GCguy