Chromatography Forum

I have GC-FID installed to detect methane composition in methane/hydrogen mixture. Methane is produced during the reaction so its composition is changing. The purpose is to find out how much methane is produce during the run time.

Now, I am able to see a peak from FID corresponding to the methane formed and I am not sure how to quantify it. I think I need calibration.

I have ordered 10%, 1%, and 0.1% methane/hydrogen mixture and I just like to collect your input about how this calibration is going to be?

I am I supposed to record the peak height corresponding to a constant calibration gas flow and make a liner plot of peak hight vs methane composition?

It looks like I have to manually integrate the peak area after the calibration then.

I really have never done this before and it is just my naive idea. Please correct me if I am wrong.

thanks

Treat the standards as if they were samples - I presume that you are injecting a certain volume of sample to the GC to produce the peak that you see.

Plot the peak height or area from the standard against the concentration of the methane in the standard. If you have Excel or something similar it will give you the best straight line equation, and you can calculate the methane concentration in samples from their peak area. Alternatively plot it on graph paper.

Your standards need to run from just below to just above the concentration in the samples - so the standards that you have will be appropriate for methane concentrations in samples of 0.1 - 10 %, but not for anything outside this range.

Your standard concentrations are not nicely spread - your calibration plot will have one point high on the right and two very close together in the bottom left corner. A 5% standard would have been better than the 1%, or if all you samples are more than 1 % drop the 0.1 5 standard.

Peter