How to Extract a UV Spectrum with the Spectrum Extraction Tool in OpenLab CDS

This Information Applies To: Agilent OpenLab CDS (Rev. 2.x)

Issue

This article outlines the step-by-step instructions on how to extract a UV spectrum with the Spectrum Extraction Tool.

Background

If your data contains UV spectral data, you can extract spectra from your chromatogram. You can either:

• Extract a UV spectrum via a right click
• Extract a UV spectrum or multiple spectra using the spectrum extraction tool.

The behavior of the spectrum extraction tool is configurable. To change the behavior, click in the Chromatograms window, and adjust the settings in the Spectrum extraction section. In the following procedure, all options are enabled.
 

Requirements

• Acquisition method in DAD is set to store All spectra see Figure 1. You can read more about parameter settings to store spectra here.

  Figure 1: Store All Spectra setting in acquisition method for DAD
  

• The injection is linked to a processing method that supports manual UV spectra extraction 3D UV Quantitative (Figure 2) or LC/MS Sample Purity (Figure 3).

  Figure 2: 3D UV Quantitative Processing Method

  Figure 3: LC/MS Sample Purity Processing Method

• To be able to carry out the procedure as described, the user needs the privileges Data Processing > Do manual spectrum extraction; Processing Method > Edit spectrum extraction parameters and Processing Method > Edit spectra parameters. Privileges are configured in the Control Panel.

Steps to Follow

1. (Optional) Extract UV background spectrum (see article How to Extract a UV Background Spectrum in OpenLab CDS)
2. In the Chromatograms window, click icon in the toolbar to start the spectrum extraction tool.
3. Move the mouse over the chromatogram. The cursor changes dynamically. It will look different, if you move it over a peak apex (Figure 4) or a baseline.

   Figure 4: Spectrum extraction cursor at peak apex

4. Click at the required position in the chromatogram (Figure 5), or to extract an average spectrum over a time range, click and drag the cursor over the required range (Figure 6).
5. When asked for confirmation, click the  icon or press [ENTER] to confirm the spectrum extraction (Figure 5 and Figure 6).
   The spectrum extraction will occur without confirmation when you clear the Confirm extraction check box in the Chromatogram Properties.
   

   
   
   Figure 5: Confirmation dialog box at peak apex
   

   
   
   Figure 6: Confirmation dialog box at selected time point.

   The extracted spectrum is shown in the UV Spectrum window.
   The time point or time range used for subtraction is shown in the spectrum name.
   The extracted spectrum is listed under the details for the individual injection in the injection tree.
   
   

6. Click Reprocess All if UV background subtraction in Processing Method is used.
7. Save the data. Extracted spectra are saved together with the data. Figure 7 shows an example of how to extract a UV spectrum using the Spectrum Extraction Tool (on both time point and time range with UV background subtraction). 
   

   
   Figure 7: Extract a UV spectrum using the Spectrum Extraction Tool
   
   

   
   You can also extract UV spectrum via a right clicking a peak or extract multiple UV spectra. See articles How to Extract a UV Peak Spectrum Via Right Click in OpenLab CDS and  How to Extract Multiple UV Spectra in One Step in OpenLab 2.x. 

Learn how to effectively operate your Agilent OpenLab CDS Software HPLC-OLII-1121e - Agilent Infinity LC Systems with OpenLab CDS – Acquisition Method e-learning course available from Agilent Education