Get Empowered: Review Window and the Processing Method | Tip #29
Tip #29: Calculating signal-to-noise ratio (Part 2)
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, calculating S/N using peak height divided by noise (#28)
- Part 2, calculating S/N from within a chromatogram (#29)
- Part 3, calculating S/N from a blank injection (#30)
- Part 4, using custom calculations to determine S/N (#31)
Let me show you how.
Bring raw data (Channels, Injections, or Sample Set) into Review and open the processing method. Click the Processing Parameters tool (Figure 1).
Click the Suitability tab and check the box that says Calculate Suitability Results. Enter the Void Volume Time; an estimate is fine (Figure 2).
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.)
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).
Select Calculate Detector Noise and Drift (Figure 5).
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.
Return to the main window and click Integrate followed by either Calibrate or Quantitate (Figure 7).
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).
On the Columns tab, find USP S/N and remove the check mark to make it visible in the table (Figure 9). Click OK.
The USP signal-to-noise ratio is displayed for every integrated peak (Figure 10).
To keep the USP S/N field in the peaks table, select Save Preferences from the File menu (Figure 11).
Finally, save all changes to the Processing Method (Figure 12).
It’s that easy!I can calculate signal-to-noise ratio in Empower! #EmpowerTips Click To Tweet
- You must have the System Suitability option and enable it in the project.
- 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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