Empower Tip: Questions from Our Readers

Question: How can I calculate the Ratio of Peak Height to Valley Height when I have a Valley Point between peaks?

Great question and the answer is simple when working with the System Suitability option in Empower Software. Often times this ratio is used as a System Suitability criterion.

If you have the System Suitability option, enable it in your Processing Method, Empower will calculate the ratio of peak height to valley height automatically. In the chromatogram we see a relatively large peak at 1.005 minutes and a smaller peak at 1.192 minutes with a valley point between the two.

Enable System Suitability in the Processing Method and enter a Void Volume Time.

Re-integrate the chromatogram. There are 2 hidden fields which are populated, Start p/v and End p/v. Start p/v calculates the ratio of peak height of the peak which has a peak start equal to the valley point. In this case it’s the height of the peak at 1.192 minutes divided by the height of the valley. End p/v calculates the ratio of peak height of the peak which has a peak end equal to the valley point. In this case is the height of the peak at 1.005 minutes divided by the height of the valley. (If my peak was in the middle of a cluster then it would calculate both for that peak.)

It’s that easy!