Get Empowered: Empower Tips #102 – A Year in Review

By January 2, 2019

Tip #102: Year in Review

Welcome back to Get Empowered and Happy New Year to all! I want to begin by saying thank you for following the blog, subscribing to the weekly email, and submitting lots of great questions this year.

As I did at the beginning of last year, I thought it would be helpful to summarize the topics we covered in 2018 and share with you a few of the questions I received.

Here is a guide to the topics we covered in 2018:

Throughout the year, we received some really great questions. I would like to share a couple which have been asked more than once:

Question 1

What is Void Volume Time and what is it used for?

  1. Void Volume Time is the retention time of an unretained component. It is used in the calculations for both ‘capacity factor’ and ‘selectivity’. You can determine the Void Volume Time by injecting something which will not be retained on the column. (This will depend on your chromatography.)
  2. Once you determine the Void Volume Time, open your Processing Method and ‘click’ on the Suitability Tab and enter the value in the ‘Void Volume Time (min)’ field (figure 1).

    Empower Tips: Suitability Tab / Enter the value in the ‘Void Volume Time (min) | Figure 1

    Figure 1

  3.  Now, the ‘capacity factor’ and the ‘selectivity’ are calculated (figure 2).
Empower Tips: Capacity factor and selectivity are calculated | Figure 2

Figure 2


Question 2

I have a small peak eluting between 2 peaks of interest. How can I calculate the resolution between the 2 peaks of interest while ignoring the small peak in between?

  1. In this example, there is a small peak between the ‘Uracil and Ethyl Paraben peaks’. We want to ignore this so we can calculate resolution between the peaks of interest. To solve this one, we will use the ‘Relative Resolution Reference’ field. Go to the Processing Method and ‘click’ on the ‘Components tab’. On the row for the ‘Ethyl Paraben peak’, select ‘Uracil’ from the drop down list in the ‘Rel Resol Field’ (figure 3).

    Empower Tips: Relative Resolution Reference' field | Figure 3

    Figure 3

  2. You’ll notice the resolution between the ‘Uracil’ and ‘Ethyl Paraben’ is calculated (figure 4). The ‘USP Resolution’ is calculated as well, however, that is the resolution between a peak and the peak which elutes just before it.
Empower Tips: Resolution is calculated | Figure 4

Figure 4


I hope you continue to Get Empowered in 2019. Keep the suggestions for future tips coming and as always, I encourage everyone to send me your questions!

Next week, we will pick up where we left off with Tip #103 and continue with our series on working with ACQUITY QDa MS data in Empower (Part 3).


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Categories: Empower Tips