Chromatography Forum

I wish to integrate a peak (arrowed in the following figure) in GC-FID chromatogram. Is the way in which I have done it proper?
Thanks
Ram

I would be very surprised if the arrowed peak is a single compound. Your problem is not with integration, it is with separation and a signal:noise ratio of only about 3 or 4:1.

Peter

Danger, Will Robinson! I would not be reporting results from that peak. As Peter points out it could be a coelution.

"If" I knew that the peak was pure, I would use valley-to-valley integration to draw in a better baseline for that peak. Or use manual integration.

Thanks all for the comments.
Does valley-to-valley integration means drawing the baseline that joins the lowest points flaking the peak of interest? If the chromatograms have high noise as seen above (is that true?), is it fine to have valley-to-valley integration rather in the way in which it is done above?

The chromatogram clearly shows that the peak is not pure. There is overlap from both sides, not to speak of the fact that one can not know where the baseline is. A semiquantitative guess is the best one can do here.

Yes, that's what I meant with the term valley-to-valley integration, that's what Hewlett-Packard called it on their electronic integrators before ChemStation.

And, like H.B. stated, this all depends upon what degree of accuracy you require for the assay: obviously, a very sharp, tall peak is best, and a peak like you show would provide a good estimate at best. So if the goal is to detect presence of someting, that's way different than a validated assay for a regulated active.

If you do report a value based on the area of this peak, you should also report that it shows extensive and unquantified overlap, and probably a co-elution with at least one other compound.

Peter