Chromatography Forum

Dear All,
I always used N2 to dry solvent because it is an inert gas and perhaps because whenever we see described in the literature (it is also cheaper than He and Ar). However, at now, I don't have N2. Would anyone tell me if the CO2 gas could be the replacement?
Thanks and regards.
Guilherme

Yes of coure , if components not intract to CO2.

Dear DSP007,
thank you for your reply.
Maybe I need to post additional information. I want to dry solvent (eg, hexane, methanol...) from my samples then resuspend them with mobile phase and inject. The samples are contituted of vitamins extrated from biological matrices (eg, whole blood, plasma or serum).
Then, perhaps the question is: what is the reactivity of CO2 in gas form and a non-aqueous system?
Someone?
Thanks.
Guilherme

Personally, I would avoid using CO2 for dryign the samples. HOwever, if it is the only gas you have, try it and compare results fror a number of samples across matricies and across conentration ranges and see how they compare.

Dear Don_Hilton,
Thanks for your reply. Yes, when I worked at another university I had N2. Now I just have CO2.
Why do you avoid the use of CO2? Some reason about reactivity of CO2?
I have thought about the particles impregnated that we see by CO2 emissions from cars, for example. Can this happen in the sample?

Several concerns with respect to the use of CO2 for drying:

For aqueous samples, exposure to high CO2 concentration may form carbonic acid, dropping the pH and possibly forming carbonate salts of basic analytes.

For non-aqueous samples, CO2 cools down upon expansion (more than many other gases); this raises the possibility of condensing atmospheric water vapor and wetting samples that would otherwise stay dry.

These may not be relevant to your situation; as Don suggested, the only way to find out is to try it and see what happens.

Be aware that carbon dioxide with the low levels of impurities that are usual for high purity nitrogen is difficult to obtain.

By far you best course of action is to do whatever is necessary to obtain nitrogen.

Peter