Empower Tip: Empower CDS User Question Answered

In this tip for Empower Chromatography Data System (CDS), we will answer an Empower user question.

QUESTION:

I have multiple groups of peaks in the chromatogram. Each group has known peaks at the start and end of each group. I want to calculate the %Area of each group not including the known peaks which border each group. Furthermore, the peaks shift in retention time from run to run. How can I accomplish this?

Great question. The short answer is to create a Custom Field which adds up the areas of the peaks in between the known peaks, divides it by the total area (automatically calculated by Empower), and multiplies by 100.

In this example, there are two groups, the first between Peaks A and B, and the second between Peaks C and D.

STEP 2:

Make sure the known peaks are identified properly, therefore, use the RT Window, Peak Match, and if necessary, the RT Reference and the RRT fields. (Note: Refer to Tip 310 for more details on using RT Reference and RRT)

Create one Result Custom Field per group.

Group 1 formula:

SUM(GT(Retention Time,A[Retention Time])&LT(Retention Time,B[Retention Time])*Area)/Total Area*100 .

Group 2 formula:

SUM(GT(Retention Time,C[Retention Time])&LT(Retention Time,D[Retention Time])*Area)/Total Area*100

The results can be viewed in the Results window within Review.

It’s that easy!