Chromatography Forum

Dear All Chromatographers,
I have a basic doubt...In theory methanol shouldn't produce signal in FID, but we can run analysis of it (samples or standards). How explain it?

I don't know the theory to which you attest, but by all the theories I have seen methanol SHOULD give a response to FID and it does quite well.

Could you explain your statement in some detail. Perhaps that would get a discussion moving on a thread.

I'm reffering about the burning of organic coupounds in the flame. I have read that the covalent bounds C-C produce ions that generate signal. Is it true? Or any covalent bounds can generate signal?

If a compound can burn in the hydrogen flame and produce ions, it should have response in FID. In this case, MEOH certainly can. If it needs C-C bond, how to expain that methane has good response in FID? that being said, MEOH should have a much weaker response than CH4 because of -OH group.

I have read studies that claim any ionization of a molecule when heated within the hydrogen flame gives a response. Oxidation is not required.
A claim is made that even hexane ionizes effectively at a rate of only 1%.

Even water seems to change the conductivity across the electrode of an FID and gives a very weak response in an FID. That being said, formaldehyde gives a very poor response to a FID, and formic acid gives almost no response at all.

Yet compounds covalently bonded can give a relatively poor response, ie Carbon Disulfide.

Any one know of any studies available out there for review?

Hi everybody
All Hydrocarbons burn in Hydrogen flame and produce very good signal, so is CH3OH, but the signal is weaker. there is a lot of articles descibing the correlation between the C number and FID response ( i have some). Water in high content just cool the environment and that produse the signal on FID.

Good lake