Empower Tip: Review Window and the Processing Method

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

If you have a QDa Mass Detector on your HPLC or UPLC 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.

We begin by bringing a channel of 3D MS data into Review.

Go to the Method Set window and Derive a Channel, selecting Single Mass.

Enter the mass of interest, the Peak Separation and select the MS Scan (3D channel) from the Function drop down list. 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 – 491.5.

Save the Derived Channel and select a Processing Method.

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

It’s that easy!