Empower Tip: Review Window and the Processing Method

When we connect two chromatographic detectors in series there is a time offset between the first and second chromatogram. This makes it difficult to overlay and compare the chromatograms. It is very easy to correct this offset by Deriving a Channel.

We start by bringing an injection with two channels in review and clicking the Overlay tool. We can see the offset between the two channels.

If we open and apply the method set we can calculate the average retention time difference which in this case is 0.075 minutes.

We can correct for this difference by reducing the Retention Time (RT) for the peaks in the second channel by 0.075 minutes. In the method set we see the two channels listed.

Right-click on Derived Channels in the Method Set Tree and select New, Derived Channel.

On the First (Only) Channel tab select Channel 2 from the Channel drop-down list

On the Filter/Offset tab enter -0.075 in the RT Offset field.

Save the Derived Channel and replace the line for channel 2 in the channel table of the method set with the Derived Channel.

Apply the method set to and now the peaks line up for an easier comparison.

It’s that easy!