Tip #48: Deriving Channels in Empower (Part 2)

Welcome back to Get Empowered! In the last tip-of-the-week blog for Empower Software, we reviewed Deriving Channels in Empower CDS (part 1).

Tip 47: Smooth a chromatogram by Deriving a Channel (part 1)

This week we will learn how to correct for the time offset between detectors that are connected in series by Deriving a Channel (part 2).

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 in Empower Software.

Let me show you how.

Step 1

We start by bringing an injection with two channels into Review and clicking the Overlay tool. We can see the offset between the two channels (Figure 1).

Figure 1

Step 2

If we open and apply the method set, we can calculate the average retention time difference, which in this case is 0.075 minutes (Figure 2).

Figure 2

Step 3

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 (Figure 3).

Figure 3

Step 4

Right-click on Derived Channels in the Method Set Tree and select New, Derived Channel (Figure 4).

Figure 4

Step 5

On the First (Only) Channel tab, select channel 2 from the Channel drop-down list (Figure 5).

Figure 5

Step 6

On the Filter/Offset tab, enter -0.075 in the RT Offset field (Figure 6).

Figure 6

Step 7

Save the Derived Channel. Replace the line for channel 2 in the channel table of the method set with the Derived Channel (Figure 7).

Figure 7

Step 8

Apply the method set and now the peaks line up for an easier comparison (Figure 8).

Figure 8

It’s that easy!

Final notes:

1. The average retention time difference could be calculated with a custom field –stay tuned for a future tip.
2. This procedure can be followed using the QuickStart or Pro interface.

Please rate this Empower Tip of the Week

Next week in Empower Tip #49: Deriving Channels in Empower (part 3)

More resources:

• Want to learn more? Check out our Empower training courses and eLearning
• Get the latest Empower projects, options, and more. Check out the New Marketplace
• See all of our tips for using Empower CDS Software
• Comments? Connect with at #EmpowerTips or @WatersCorp on Twitter.
• Submit an Empower 3 Review with Select Science.  Write a review.