Chromatography Forum

Hi,
I am running a multi component gas sample on FID & TCD detectors. Methane appears on both detectors but I do not integrate it on the TCD channel. Is this correct if I am performing normalization ? Are you suppose to integrate every peak? I would think to integrate methane twice would be incorrect. The only compound I integrate on TCD is nitrogen.

I think normalization is proper when you consider all the substances entered into system as 100% (i.e. sum of EVERY peak response on single detector) and calculate appropriate part of each compound. Ci=Ai/sum(Aj) , i,j=1..N
This is done per detector as different detectors have different RRFi

You can also normalize against the biggest peak on a chromatogram, or another peak which may or may not be an internal standard.

Peter

We the same issue of methane, using multi detectors for gas analysis. We are using FID and 2 TCD. We do normalization for the peaks of interest only, which are calibrated by external standard and those none of interest we don't calibrate the GC for.

For methane issue, we do calibration for methane on FID not on TCD and accordingly we do analyse the sample for methane on FID not TCD as well.

regards.