Tip #56: Deriving Channels in Empower (Part 9)

Welcome back to Get Empowered! In our last tip-of-the-week blog for Empower Software, we reviewed Deriving Channels when working with 3D PDA chromatography data in Empower.

• Tip 47: Smooth a chromatogram by Deriving a Channel (part 1)
• Tip 48: Correct for the time offset between detectors connected in series by Deriving a Channel (part 2)
• Tip 49: Subtract a baseline from a 2D chromatogram by Deriving a Channel (part 3).
• Tip 51: Subtract a 2D baseline from 3D PDA data by Deriving a Channel (part 4).
• Tip 52: Derive MaxPlot from 3D PDA data (part 5)
• Tip 53: Derive TotalPlot from 3D PDA data (part 6)
• Tip 54: Derive RatioPlot from 3D PDA data (part 7)
• Tip 55: Derive Timed Wavelength from 3D PDS data (part 8)

In this tip, we will discuss Deriving Channels when working with 3D mass (MS) data.

If you have an ACQUITY QDa Mass Detector on your HPLC or UPLC instrument and collect 3D MS data, there are a number of options for deriving a channel, such as Single Mass, TIC plot, and MaxPlot, etc. What do these choices mean?

In today’s tip, we’ll discuss deriving Single Mass from 3D MS data. Single Mass is analogous to deriving a Single Wavelength when working with 3D PDA data.

Let me show you how it is done.

Step 1

We begin by bringing a channel of 3D MS data into Review (Figure 1).

Figure 1

Step 2

Go to the Method Set window and Derive a Channel, selecting Single Mass (Figure 2).

Figure 2

Step 3

Enter the mass of interest, the Peak Separation, and select the MS Scan (3D channel) from the Function drop-down list (Figure 3). The Peak Separation allows you to specify a tolerance range or “window” that is used when extracting a chromatogram from a 3D MS data set. The values of the window are defined as:

• Upper range: all masses < [mass + (0.5 x peak separation value)]
• Lower range: all masses > [mass – (0.5 x peak separation value)]

The intensity value used in the chromatogram is the sum of all peaks in the window (greater than or equal to the lower value and less than the upper value). If no peaks fall in the range, the intensity value is 0. In this example, 491 is entered with a Peak Separation of 1, therefore, the range will be from 490.5 to 491.5.

Figure 3

Step 4

Save the Derived Channel and select a Processing Method (Figure 4).

Figure 4

Step 5

Return to the main window and apply the Method Set. The Single Mass chromatogram is displayed (Ffigure 5).

Figure 5

It’s that easy!

Final note: This procedure can be followed using the QuickStart or Pro interface.

Please rate this Empower Tip of the Week

Next week in Empower Tip #57: Deriving Channels in Empower (part 10).

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