Get Empowered: Reader Question on Calculating Peak Valley Points | Tip #79

By July 26, 2018


Tip #79, Reader question: How do you calculate the height of the valley point between two fused peaks?

Welcome back to Get Empowered! In the last Empower tip-of-the-week post for Empower CDS Software, we answered a reader-submitted question and learned how to quantitate impurities against the main component. (Tip #78)

(See the link at the bottom of our post to see previous questions, ask your own question, or to provide a tip of your own!)

In this week’s tip, I’ll answer a question as a follow-up to Tip #74 on using Empower’s System Suitability option to calculate the ratio of peak to valley height when there’s a valley between the chromatographic peaks.

Question: How can we calculate the height of the valley point between two fused peaks?

Another great question.

Let me show you how it is done.

Step 1

If we recall from Tip #74, the ratio of peak height to valley height is calculated as start p/v or end p/v.  The height of the relatively big peak at 1.005 minutes ends at a valley point, so Empower Software reports the end p/v.  The peak at 1.192 minutes starts at a valley point so Empower reports the start p/v (Figure 1).

Empower Tips: Ratio of peak height to valley height is calculated | Figure 1

Figure 1

Step 2

If we solve for valley height, the calculation would be valley height = peak height/start p/v or peak height/end p/v (Figure 2).

Empower Tips: Solve for valley height | Figure 2

Figure 2

Step 3

This is a simple peak custom field in Empower (Figure 3).  (You can make a similar one substituting end p/v.)

Empower Tips: Simple peak custom field | Figure 3

Figure 3

Step 4

We see the result of the calculation in the peaks table in Review. The valley height is the same regardless of which calculation we use (Figure 4).

Empower Tips: Result of the calculation in the peaks table | Figure 4

Figure 4

 

It’s that easy!

Final Notes: 

  1. We will do a series of Empower Tips on Custom Fields later this year… Stay tuned!
  2. This procedure can be followed using the QuickStart or Pro interface.

 

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Previous questions we’ve answered:

 

Next week in Empower Tip #80 – How to use the Result Audit Viewer

 

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