Defining Detection Parameters
Modifying the Baseline

It may be necessary to modify the baseline, especially for non-resolved peaks. The baseline is usually defined via a mathematical procedure. For calculating the individual peak areas, a perpendicular is dropped to the baseline from each local minimum (standard).

If you think that integration starts too early or that the peak end is delayed, you can force a better peak start or end by inserting a Baseline Point.

If a series of non-resolved peaks is piled on an "absorption mount", for example, due to increased solvent absorption, the Valley to Valley detection parameter can be used to force the baseline from minimum to minimum via.

Single peaks that are piled on a recognizable "absorption mount" are integrated individually. To integrate the entire area, the baseline can be fixed. Setting the Lock Baseline parameter to At Current Level extrapolates the baseline horizontally to the intersection with the signal curve. Setting the parameter to At Global Minimum searches for the absolute minimum in the direction of the peak end or until the next Lock Baseline. Both parameters disable the Valley to Valley parameter.

 Tip:

In all these actions, the Peak Type classification criterion of the peak table has priority. For a Baseline-Main-Baseline type peak, the peak limits always have baseline contact.

As an alternative, you may modify the baseline manually (refer to Working with Chromatograms/Manual Re-Integration  Modifying the Baseline Manually.)