Get Empowered: Reader Question on Calculating Peak Valley Points | Tip #79
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.
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).
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).
This is a simple peak custom field in Empower (Figure 3). (You can make a similar one substituting end p/v.)
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).
It’s that easy!
- We will do a series of Empower Tips on Custom Fields later this year… Stay tuned!
- This procedure can be followed using the QuickStart or Pro interface.
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Previous questions we’ve answered:
- How can I calculate the ratio of peak height to valley height when I have a valley point between peaks?
- Why is the retention time of my peak slightly different than the retention time of the UV apex spectrum for the peak?
- How do you calculate impurity response when there are two APIs in the sample?
- How do you summarize specified and unspecified impurities in a sample and quantitate them against the main component?
- How do you quantitate impurities against the main component?
Next week in Empower Tip #80 – How to use the Result Audit Viewer
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