Empower Tip: Review Window and the Processing Method

If you work in a pharmaceutical company you follow the pharmacopeia for your methodology. There are 2 ways Empower can calculate signal-to-noise ratio adhering to the pharmacopeia. This tip will address calculating noise from a blank injection.

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

Click the Suitability tab and check the box that says Calculate Suitability Results. Enter the Void Volume Time, an estimate is fine.

Select Calculate USP, EP, and JP s/n.

Select 'Use noise centered on peak region in blank injection'. Empower calculates peak-to-peak noise from the expected retention time for the peak(s) in the blank injection. The half-height multipliers set the window of time empower uses to calculate noise in the blank injection. For example, empower calculates the half-height width of a peak and multiplies by the value in the half-height multiplier field. If the peak width was 15 seconds at half height and the multiplier is 5, then the window would be 75 seconds. It does this for each peak.

Save all changes to the Processing Method and return to Browse Project.

Now we need to identify the blank injection in the Sample Set. On the Sample Sets tab, right click on the Sample Set and select Alter Sample.

Right-click on the table and select Table Properties.

On the Columns tab, find the Blank field and deselect the check mark, then click OK.

Now that the Blank field is added to the table, check the box for the blank injection.

Save all changes and exit out of Alter Sample.

Process the data.

Bring the Result Set or an individual Result into Review.

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.

On the Columns tab, find USP s/n and remove the check mark to make it visible in the table. Click OK.

The USP signal-to-noise ratio is displayed for every integrated peak.

To keep the USP s/n field in the peaks table, select Save Preferences from the File menu.

It’s that easy!