Dealing with overintegration because of drift

[BenFirth]

Not sure if "drift" is the right word. There are two groups of peaks, D and T, at the end of my chromatograms. When they are present, they tend to form a bit of a lump in the baseline. This is not a major problem when there are significant amounts of D (top GC).

However, when there's only a small amount of D present, clarity tends to integrate the whole lump, and D ends up being overintegrated (bottom GC).

I'm not sure what setting is best to deal with this. I really just want Clarity to only integrate the ones that are obviously peaks. There is a substantial variation in peak widths across a chromatogram, as the larger peaks in the T group can be 2 or 3 times the size of some other peaks. Any ideas what Integration settings I should use/change?

[Daniel Mentlik]

Dear Ben,
I will probably need some additional information before suggesting the correct solution. May I get some more insight on your analysis?

In particular, I would like to know whether the retention times of the peak groups D and T change significantly (by a minute or so), whether I can expect some other peaks in the area (which should not be evaluated) and whether the overall peak shape of the whole groups change too (or can I say that always there will be small peak in group D, followed by larger peak, followed by possibly one or two small peaks more)?

My first idea for the situation would be application of reference peak marks to peaks 20.11/20.22 (lower/upper graph) and 24.18/24.19, followed by application of some peak-specific thresholds. That would remove the "lump" at time 21.45 on a lower graph from the integration, if that is the aim...

Please send me sample chromatogram of both cases to support@dataapex.com so I may try to finetune the parameters and send them back.

Best Regards,
Daniel