Empower Tip: Review Window and the Processing Method

In this tip, we will learn how to look at the second derivative of a chromatogram.

Many of you use the Apex Track peak detection and integration algorithm. Apex Track detects peaks from the second derivative of the chromatogram and a number of you have asked, “How do I look at the second derivative of my chromatogram?” Looking at the second derivative can make it easier to identify co-eluting peaks.

We begin by bringing an injection into Review, open and apply the Method Set.

Derive a Channel and on the First (Only) Tab select the channel from the Channel drop down list.

On the Filter/Offset tab select Second from the Derivative drop down list.

Click OK, save the Derived Channel with a name and add it to the Method Set along with a Processing Method.

Return to the Main Window, apply the Method Set and click the Overlay tool.

It is very difficult to see the overlay and we can improve the display by going into the properties of the chromatogram and set the overlay to Make Stack Plot. (Optionally, you can clear the integration from the Edit menu.)

If you want to get a closer look at the second derivative you can zoom in on it much like you would on a chromatogram.

It’s that easy!