Empower Tip: Review Window and the Processing Method

In the last example, we wanted to express the impurity response as % adjusted area while excluding certain peaks (like a system peak) from the calculation. In this example, we are going to express impurity response as % area against the main peak. We could create a custom field to make the calculation or we could use the features in Empower which are designed just for this purpose.

Let’s start by bringing a sample set into Review, open the processing method, click the processing method tool, and click the Impurity tab.

For the Impurity Response, select % Area Against Main Component from the drop-down list. The calculation is (area of peak/area of main peak) x 100.

Now let’s select the name of the main peak from the Main Component drop-down list.

Return to the main window and click Quantitate. The original %Area is next to the Impurity Response. (I did adjust the precision for the %Area field from 2 to 3.)

If we look at Impurity E the original %Area is 0.561% and now compared to the main peak it is 0.568% which makes sense since the area of the peak is now compared to the area of the main peak which less than the total area for all peaks. (Hint – remember that you can see the total area by going to the Results window within Review and check the middle table called Chromatogram Result.)

It’s that easy!