Get Empowered: Browse Projects | Tip #8

By March 14, 2017

Tip #8: Comparing Calibration Curves

Subscribe to the Empower Tips BlogIn the last Empower Tip of the Week for Empower Chromatography Data Software (CDS), we explored how to use an older version of a method. Here, we explore how to compare calibration curves.

There are times when we might want to visually compare calibration curves by overlaying them. Reasons for this are:

  • Method validation where we want a visual check of the consistency of the slope of the calibration curve
  • Visual check of change in response over time

Before we get started, please note that you must log into Empower with the Pro interface to use this feature.

Step 1

Starting on the Curves tab in Browse Project, highlight two or more curves.  Right click on one of the highlighted curves and select Compare (Figure 1).

Empower Software: Compare Curves | Figure 1

Figure 1

Step 2

The Compare window opens and we see an overlay of the calibration curves in the upper half of the window and a list of the curves we chose to work with in the lower half of the window (Figure 2).

Empower Software: Compare Curves | Figure 2

Figure 2

Step 3

The curve highlighted in red in the table is active. (If you click the row number for one of the other curves that curve becomes the active one)  If you click the Individual Points tab in the lower left corner of the window it displays the individual point table for the active curve (Figure 3).

Empower Software: Individual Points | Figure 3

Figure 3

Step 4

There is more information regarding the calibration curve points than what is displayed in this table. Right-click in the table and select Point Information (Figure 4).

Empower Software: Point Information | Figure 4

Figure 4

Step 5

This opens a much more detailed table (Figure 5).  Scroll to the right to see the other fields of information.

Empower Software: Detailed table | Figure 5

Figure 5

Step 6

The plot can easily be modified by right clicking in the plot and selecting Properties (Figure 6).

Empower Software: Properties | Figure 6

Figure 6

Step 7

Select the LC Calibration tab to select which points you want displayed.  (Figure 7)  You can select the overlay tab to change the way the curves are displayed, such as overlay in stack plot.

Empower Software: Plot Properties | Figure 7

Figure 7

A couple of final notes:

  1. You cannot make any changes to the calibration curve points in the Compare window. Its purpose is strictly to compare the curves.
  2. You can compare calibration curves across multiple projects … and I will cover that in an upcoming tip – so stay tuned!

Next week in Tip #9, we will explore how ID numbers are assigned in the Empower CDS project.

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