The peak-to-valley ratio is indicator for the resolution of two or more unresolved peaks.
It's defined by the peak heights divided by the relative height of the valley in between 2 peaks.
OpenLAB CDS ChemStation writes a Peak_LevelStart vlaue to the ACAML result file that can be used for this calculation. The Peak_LevelStar always refers to the start of the peak, so the following calculation always refers to the valley left to the peak.
Use the expression =Peak_Height/Peak_LevelStart
It will return the same numbers back as classical ChemStation reports.
If the relative baseline level between two peaks is 0, the stored value is in fact very small (10 exp-20) and the calculation results in a very large number.
You may want to round (cut off) the level start to 10 digits, like
This will result in an error for those peaks where the calculation makes no sense.
(originally posted in OpenLAB Forum: zohodiscussions.com/openlabcdsforum#Topic/68030000000019015
2012 July 6
by Bernhard Etrich)