Get Empowered: Review Window and the Processing Method | Tip #29

By August 9, 2017

Tip #29: Calculating signal-to-noise ratio (Part 2)

In the last tip-of-the-week blog for Empower Software, we explored one of the ways to calculate signal-to-noise ratio. This tip will demonstrate a second way.

If you work in a pharmaceutical company, you follow the pharmacopeia for your methodology. There are two ways Empower Chromatography Data Software can calculate signal-to-noise (S/N) ratio adhering to the pharmacopeia. This tip will address calculating noise from within the chromatogram. [Part 1 (#28) | Part 2 (#29) | Part 3 (#30)]

Let me show you how.

Step 1

Bring raw data (Channels, Injections, or Sample Set) into Review and open the processing method. Click the Processing Parameters tool (Figure 1).

Empower Tips: Processing Parameters tool | figure 1

Figure 1

Step 2

Click the Suitability tab and check the box that says Calculate Suitability Results. Enter the Void Volume Time; an estimate is fine (Figure 2).

Empower Tips: Calculate Suitability Results/Void volume time | figure 2

Figure 2

Step 3

Select Calculate USP (U.S. Pharmacopeia), EP (Europe Pharmacopeia), and JP (Japan Pharmacopeia) S/N (Figure 3). (Deselect Use noise centered on a peak region in blank injection will be addressed in the next tip.)

Empower Tips: Calculate USP, EP and JP s/n | figure 3

Figure 3

Step 4

Select where in the chromatogram you want noise calculated by clicking the Noise and Drift tab. Click Yes to the message that appears (Figure 4).

Empower Tips: Noise and Drift tab | figure 4

Figure 4

Step 5

Select Calculate Detector Noise and Drift (Figure 5).

Empower Tips: Calculate Detector Noise and Drift | figure 5

Figure 5

Step 6

Enter a time region in the chromatogram that is free of peaks (Figure 6). This time region must be equal to or greater than the Segment Width and must contain at least 60 data points. The Segment Width is used for calculating average noise and drift values and it must contain at least 30 data points.

Empower Tips: Enter time region in the chromatogram | figure 6

Figure 6

Step 7

Return to the main window and click Integrate followed by either Calibrate or Quantitate (Figure 7).

Empower Tips: Integrate> Calibrate/Quantitate | figure 7

Figure 7

Step 8

USP S/N, EP S/N, and JP S/N are hidden fields by default, so let’s add one to our Peaks table. Right-click on the Peaks table and select Table Properties (Figure 8).

Empower Tips: Peaks table > select Table Properties | figure 8

Figure 8

Step 9

On the Columns tab, find USP S/N and remove the check mark to make it visible in the table (Figure 9). Click OK.

Empower Tips: Remove check mark | figure 9

Figure 9

Step 10

The USP signal-to-noise ratio is displayed for every integrated peak (Figure 10).

Empower Tips: USP signal to noise ratio displayed | figure 10

Figure 10

Step 11

To keep the USP S/N field in the peaks table, select Save Preferences from the File menu (Figure 11).

Empower Tips: Keep USP s/n field in peaks table | figure 11

Figure 11

Step 12

Finally, save all changes to the Processing Method (Figure 12).

Empower Tips: Save in Processing Method | figure 12

Figure 12

It’s that easy!

I can calculate signal-to-noise ratio in Empower! #EmpowerTips Click To Tweet

Final notes:

  1. You must have the System Suitability option and enable it in the project.
  2. This procedure can be followed for both the QuickStart and Pro Interfaces.


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Next week in Empower Tip #30: Calculating Signal-to-Noise Ratio (Part 3)


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