Chromatography Forum

I am having a problem getting ChemStation to stop skimming underneath a peak on my chromatography results. The particular compound is between two valleys as one of six co-eluding peaks. What I want to happen is for ChemStation to split the peaks at the valleys with drop lines to the baseline. What is happening is that ChemStation is cutting the particular compound horizontally between valleys - I would label it tangent skimming if not for how persistent it is being. I have tried using the events to turn tangent skimming off. I have tried splitting the peaks with an event. Neither has even moved the horizontal boundary. Everything I’ve read in the manuals even says tangent skimming is turned off. So what am I doing wrong, and how can I get ChemStation to do what I want without manually having to integrate this every time?

Have you tried using the Baseline Backwards command? I am not sure it will work for this, but can always try it.

No go, although I did get some indication that it may be in the settings for how ChemStation detects slopes by trying it; I set up the backward baseline, and it stopped detecting the last two of my peaks altogether! Although the two peaks are among the smallest of the six peaks there, they are still sizable compared to other peaks in the run. Any other suggestions?

It is a long time since I used Chemstation, but it sounds as if you have valley to valley baseline, not tangent skimming, which is why turning tangent skimming off does not make any difference. Look for a valley to valley baseline event, and remove it.

Peter

If this is the Genie integrator (and the baseline all valleys is not the issue), there is some interaction between the threshold and the peak width settings. I think a higher threshold will force a more horizontal baseline, but it will requires testing with various peak widths.