Get Empowered: Review Window and the Processing Method | Tip #33

By September 7, 2017

Tip #33: Reusing an Older Calibration Curve

Welcome back to Get Empowered! In the last Empower tip-of-the-week blog for Empower Software, we explored how to overlay a chromatogram at a particular wavelength from two different 3D PDA channels. This week we will learn how to re-use an older calibration curve for quantification.

From time to time I get the question of how to use an older calibration curve to quantitate samples. Every time you calibrate, Empower assigns a Calibration ID to the calibration curves generated. If you want to use a calibration curve other than the current one, you need to select the older curve using the Calibration ID number. Sound difficult? Not really.

Let me show you.

Step 1

Let’s start from the Curves tab in Empower Softwarae’s Browse Project. The current calibration has ID 6240 and the older calibration has ID 6213 (Figure 1). Let’s first look at the difference between them using the Compare window. (You may recall we covered that in Tip 8, Comparing Calibration Curves.)

Empower Tips: Curves tab in Browse Project | figure 1

Figure 1

Step 2

In Compare Window with Calibration ID 6240 highlighted, click the Individual Points tab (Figure 2).

Empower Tips: Compare window/individual points tab | figure 2

Figure 2

Step 3

The X Values for the three levels are 0.02, 0.05, and 0.1 respectively (Figure 3).

Empower Tips: X Values | figure 3

Figure 3

Step 4

The older Calibration ID of 6213 has X Values that are slightly lower due to a Purity factor that was applied (Figure 4). Our goal is to use this older calibration curve where the Purity factor had been applied.

Empower Tips: Older calibration curve where Purity factor is applied | figure 4

Figure 4

Step 5

Let’s now bring a Result Set or a Result into Review and click the Calibration Curve tool (Figure 5).

Empower Tips: Result set review/calibration curve tool | figure 5

Figure 5

Step 6

In the Calibration Curve window go to Options, Select Calibration (Figure 6).

Empower Tips: Calibration curve window /calibration | figure 6

Figure 6

Step 7

Select the Calibration Curve you want to use (in this case Calibration ID 6213) and click OK (Figure 7).

Empower Tips: Select calibration curve | figure 7

Figure 7

Step 8

Click OK to the warning message that says the calibration you have selected is not the most current (Figure 8).

Empower tips: Calibration warning | figure 8

Figure 8

Step 9

Calibration curves are associated with the processing method, so from the File menu select Save As, Processing Method to give the method a different name (Figure 9).

Empower Tips: Save As/Processing Method/Rename | figure 9

Figure 9

Step 10

You will be asked to Clear Curves or Copy Curves. Select Copy Curves (Figure 10).

Empower Tips: Save calibration method with calibration curves | figure 10

Figure 10

Step 11

Enter a new name for the Processing Method and click Save (Figure 11).

Empower Tips: Enter new name for the processing method | figure 11

Figure 11

Step 12

Exit from Review and now process the Sample Set using the older calibration curve. Go to the Sample Sets tab in Browse Project, right-click on the Sample Set and select Process (Figure 12).

Empower Tips: Sample Sets tab/Browse Project/Sample Set/Process | figure 12

Figure 12

Step 13

In the Background Processing and Reporting dialogue box select the Processing Method with the different name, and from the How drop-down menu select Quantitate Only (Figure 13). Then click OK.

Empower Tips: Quantitate Only | figure 13

Figure 13

Step 14

Go to the Result Sets tab, right-click on the new Result Set and select Review (Figure 14).

Empower Tips: New result set and select review | figure 14

Figure 14

Step 15

Click the Calibration Curve tool (Figure 15).

Empower Tips: Calibration curve tool | figure 14

Figure 14

Step 16

As seen in our example, the X Values for Uracil are from the older calibration curve (Figure 16).

Empower Tips: older calibration curve | figure 16

figure 16

Step 17

If we compare the results for a sample, we see a different calculated amount for Uracil when we use the older calibration curve (Figure 17). Want to know how to create this report? Stay tuned for future tips on Report Methods.

Empower Tips: Older calibration curve results | figure 17

Figure 17

It’s that easy!

I can reuse an older calibration curve to quantitate samples in Empower! #EmpowerTips Click To Tweet

Final notes:

  1. This procedure can be followed using Empower’s QuickStart or Pro interface with 1 exception – the Compare window is accessed only through the Pro interface. Otherwise, the rest of the procedure can be followed.
  2. You could start with raw data (Sample Set, Injection, or Channel). Once you take the raw data into Review, open the Processing Method and then proceed from step 6.
  3. Typically this would not be seen as good practice in a regulated laboratory.


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Next week in Empower Tip #34: Extracting Chromatograms and Spectra from 3D PDA Data (Part 1)


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Categories: Empower Tips