Chromatography Forum

Hi,
I want to analyse MeOH (0-300ppm MeOH) concentration in N2 and carbon oxides mixture. I have TCD and FID. N2, CO and CO2 are separated on mol sieves and analysed on TCD. One and only substance which give a signal on FID is MeOH (separation not necessary). I have an idea to use an empty column on line conected to FID, and use slow carrier gas flow. Have somebody tried it? Will FID work correctly?
Thanks for answers.

how are you introducing your sample onto the column? This will greatly affect the outcome of your suggestion.

What you describe is basicly a simple distillation column.

There are so many columns, capillary and packed, that will perform the analysis you desire and separate methanol from possible interferences why not use one of them?

PEG cap and packed columns, Carbopack packed, 624, 1701, 5% Phenyl, porous polymer, all will work, although I would suggest a PEG capillary or a 6.6% Carbowax 20M on Carbopack B 80/120 as preferred capillary and packed column choices.

Good luck.

Rod

My problem is strange , I hope it matches to this forum.
I have to analyse methanol formed in catalytic reaction as a function of catalyst temperature. One and only product which is interesting for me is MeOH. So I want to modify my chromatograph: remove sample loop and packet column (separation not required) currently used and install empty glass column between FID and my microreactor (can't be placed in chromatograph furnace) in which methanol formation reaction runs.
Temperature in microreactor can be increased linearly and gas passing catalyst analysed on FID (signal only from MeOH).
I haven't started do that, I don't know if it has sense. I know that TCD can be directly connected with microreactor in this way, what about FID, is there a risk of damage or ... etc?
Regards

So basically, what you want is to generate a continous FID signal (which would, presumably, be proportional to the MeOH concentration in the feed stream) instead of giving it "pulses" of analyte as you would in a chromatographic system

As long as you keep to the same volumetric flow rate that the FID is designed for (i.e., comparable to what you would use in the GC column), I can't think of any way the detector would be damaged. Areas of concern would be
- build up of crud on the electrode and the jet. In effect the detector would be generating "signal" continously instead of now and then. If you give it too high a concentration, you can get soot build up
- the ability to "zero" the detector signal now and then to compensate for any drift.