Get Empowered: Review Window and the Processing Method | Tip #119, ACQUITY QDa MS Data

By May 1, 2019


Tip #119: Working with ACQUITY QDa MS data in Empower Software (Part 19)

Welcome back to Get Empowered! In the last Empower tip-of-the-week post for Empower Chromatography Data Software, we learned how to work with the Timed Mass Chromatogram from the Review Main Window (Tip #118).

Working with ACQUITY QDa MS data in Empower:

  • #100: How to view the base mass and mass spectra for the peaks in a chromatogram
  • #101: How to work with 2D ACQUITY QDa MS data
  • #103: Viewing different spectral views in the Mass Analysis window
  • #104: Extracting chromatograms and spectra while working in the Mass Analysis window
  • #105: Why it is important to align chromatograms when collecting data from both a PDA and a ACQUITY QDa mass detector
  • #106: How to optimize sensitivity by extracting a single mass rather than working with a TIC plot
  • #107: How to smooth the chromatogram using the Processing Method
  • #108: How to smooth the chromatogram using a Derived Channel in the Method Set
  • #109: How to track peaks using the ACQUITY QDa mass detector
  • #110: Using CODA (component detection algorithm) as a tool when scouting for peaks
  • #111: Using MS 3D subtraction to remove background interference
  • #112: How to create a MS Spectra Library from data collected with the ACQUITY QDa mass detector
  • #113: How to use a MS Spectra Library to identify spectra from unknown peaks via the manual technique
  • #114: How to use a MS Spectra Library to identify spectra from unknown peaks via the automated technique
  • #115: How to display MS spectra from a particular MS scan along with UV spectra in the Mass Analysis window
  • #116: How to do Component-based Expected Mass Processing
  • #117: How to do Injection-based Expected Mass Processing
  • #118: How to work with the Timed Mass Chromatogram from the Review Main Window

In this week’s tip, will we will learn how to use a function called Combine Spectrum. This creates a single, summed, or averaged scan from selected spectra across a chromatographic peak or baseline, yields an enhanced signal to noise ratio, and thus improves mass accuracy. It can also be used as a quick check of spectral homogeneity.

Let’s get started.

EXAMPLE 1

Step 1

We start by bringing a 3D MS channel into Review, extract a TIC plot, and integrate a peak. Note the spectrum for the peak (figure 1).

Empower Tips: Extract a TIC plot, and integrate a peak | Figure 1

Figure 1

Step 2

Click on the Combine Spectrum tool (or select Combine Spectrum from the Process Menu). This dialogue box allows us to either average or sum spectra across a peak and subtract a baseline spectrum from all spectra selected across that peak (figure 2).

Empower Tips: Dialogue box to either average or sum spectra | Figure 2

Figure 2

Step 3

Right click, and while holding down the button, drag the cursor thru the peak to select the portion of the peak you want to use for the average. Repeat the procedure by right clicking and dragging the cursor thru a portion of the baseline (figure 3).

Empower Tips: Select the portion of the peak you want to use for the average | Figure 3

Figure 3

Step 4

The ‘Average’ and ‘Subtract’ fields are now populated. Click ‘Apply’ or ‘OK’ to view the combined spectrum in Spectrum Review. The original apex spectrum for the peak was an average of 5 spectra as set in the Processing Method. The combined spectrum was an average of 23 spectra (figure 4). In this case there is very little difference between the 2 spectra.

Empower Tips: The ‘Average’ and ‘Subtract’ fields are now populated | Figure 4

Figure 4

EXAMPLE 2

Step 5

Repeating the process with a different peak, you will notice a significant difference between the apex spectrum and the combined spectrum which indicates spectral heterogeneity and further investigation of this peak should be done (figure 5).

Empower Tips: Notice significant difference between the apex spectrum and the combined spectrum | Figure 5

Figure 5

It’s that easy!

Final notes:

  • This procedure can be followed using the QuickStart or Pro interface.
  • ACQUITY QDa Mass Detector is compatible with the Alliance HPLC system.

 

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Next week in Empower Tip #120 – We will continue this series on working with ACQUITY QDa MS data in Empower (Part 20).

 

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Categories: Empower Tips