Empower Tip: Review Window and the Processing Method

In this tip, we will discuss another option for Deriving Channels when working with PDA data, called Timed Wavelength.

Have you ever had a sample where each component had a different lambda max and it was difficult to pick one wavelength to use for quantitation? We learned in Tip 52 that MaxPlot plots each point in time at the maximum absorbance across the collected wavelength range. From a method development viewpoint this gives us a quick and easy way to see the lambda max for each component. However, MaxPlot is typically not used for quantitative purposes. Timed Wavelength creates a channel that specifies a wavelength at specified starting times. This maximizes sensitivity and allows us to perform quantitation for all components regardless of the differences in lambda max. (It is analogous to wavelength programming in the instrument method for a UV detector except this being done post run.)

We begin by bringing a channel of PDA data into Review and deriving MaxPlot using the Extract Choices drop down list. We see 3 peaks each with a different lambda max – 257, 289 and 244nm.

Go to the Method Set window and Derive a Channel, selecting Timed Wavelength.

Enter the time and the wavelength to be displayed for each component.

Save the Derived Channel and select a generic processing method.

Return to the main window and apply the Method Set. The Timed Wavelength chromatogram is displayed.

It’s that easy!