How to integrate merged peaks in OpenLab CDS

Document created by carlos_vargas Employee on May 19, 2020Last modified by carlos_vargas Employee on Oct 7, 2020
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This Information Applies To: OpenLab CDS 2.X



How to integrate non-ideally separated peaks starting above the zero baseline in OpenLab CDS?



Integrating merged peaks is a classical challenge in chromatography in case two compounds cannot be fully separated. This post outlines some key steps and references to helpful resources on how to address this problem.


What are merged peaks?

  • Merged peaks occur when a new peak begins before the end of peak is found. The figure illustrates how the integrator deals with merged peaks. 



How to integrate merged peaks in OpenLab CDS?

  • General recommendation is to optimize the chromatography to fully separate peaks. 
  • In case you cannot avoid coelution, optimize the automated integration to avoid unnecessary use of manual integration, which is prone to avoid human error and interpretation
  • Start by defining starting integration events, then fine-tune the integration results.



Peak Valley Ratio

The Peak to valley ratio is a measure of quality, indicating how well the peak is separated from other substance peaks. This user-specified parameter is a constituent of advanced baseline tracking mode. 

  • By adjusting the peak to valley ratio, you can decide if two peaks that do not show baseline separation are separated using a drop line or a valley baseline.




  • The peak-to-valley ratio is calculated using the following equations:
    H1 ≥ H2, Peak valley ratio = H2/Hv
    H1 < H2, Peak valley ratio = H1/Hv

  Peak Valley Ratio OpenLab CDS


Please note that in regulated environments  you always need to refer to the guidelines outlined in your SOPs for integration parameters.




Keywords: Software, OpenLab, CDS

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