Using Reference Chromatograms in OpenLab CDS Data Analysis

Answer

This Information Applies To: Agilent OpenLab CDS software (Version 2.6 or later) 

Issue

With reference chromatograms, you can do a quick visual comparison of sample chromatograms against another, specified chromatogram. Reference chromatograms are stored in the processing method. You can therefore use the same reference chromatograms for all injections that you link to this method.

Requirements

• To be able to carry out the procedure as described, you need the privilege Processing Method > Edit signal parameters. Privileges are configured in the Control Panel.
• If the project enforces method approval, the method status must be Generic.

Steps to Follow

Adding reference chromatograms

Removing reference chromatograms

Displaying the reference chromatogram

Adding reference chromatograms

1. Load the results that you want to use as a reference. (Figure 1)
   
   

   
   
   Figure 1. Loading the results 
   
   

2. Open the method to which you want to add the reference chromatograms.
3. In the Processing Method window, click the General > Signals node. (Figure 2)
4. Click the Reference Chromatogram tab. (Figure 2)
   • If you have changed your data in the meantime, save all results.
   • Only saved data can be added as a reference chromatogram.
     

     
     
     Figure 2. Signals node
     
     

5. To add reference chromatograms, click the [ + ] button  (Figure 3). You can add up to five reference chromatograms.

   
   
   Figure 3. Adding chromatograms
   
   

6. In the Select reference chromatogram dialog box, select the injection that you want to use as a reference. Click in the Signal field to select the desired signal from the drop-down menu. (Figure 4)
   

   
   
   Figure 4. Selecting the Signal 
   
   

   • By default, the dialog box shows the focused injection plus all pinned injections.
   • The Signal drop-down list shows all signals for the selected injection that are supported for reference chromatograms and that are currently displayed in the Chromatograms window.
   • MSD signals, 2D-LC signals, chromatograms created by data extraction, and instrument curves are not available as reference chromatograms.
   • Each reference chromatogram is identified by the injection and signal that you choose in the Select reference chromatogram dialog box. If a reference chromatogram already exists for a specific injection and signal, the existing reference chromatogram will be updated.
     
     
7. To select a signal from another loaded injection, clear the check box at the top of the dialog box. (Figure 5)
   

   
   
   Figure 5. Selecting reference chromatograms from other injections
   
   

   • The dialog box then offers all loaded injections with all of their signals.
   • MSD signals, 2D-LC signals, chromatograms created by data extraction, and instrument curves are not available as reference chromatograms.
     
     
8. Click OK for displaying a list of added signals. (Figure 6)
   
   

   
   
   Figure 6. Reference Chromatogram list
   
   

9. Save the method, and link it to the relevant injections.
   • If the audit trail is activated for your method, an entry about adding the reference chromatogram will be added to the method audit trail. The audit trail entry includes the version number of the result set that you used as a reference.

Removing reference chromatograms

1. In the Processing Method window, click the General > Signals node. (Figure 7)
   
   

   
   
   Figure 7. Signals node

2. Click the Reference Chromatogram tab.
3. Select the reference or references that you want to remove, and click the [ - ] button.
   
   

Displaying the reference chromatogram

Note: A processing method must be linked to the displayed injection, and at least one reference chromatogram must be available in the processing method.

1. In the Chromatograms window, click the Show reference chromatogram from method icon to display or hide the reference chromatograms that are available in the linked method (Figure 8) The icon is only visible if a reference chromatogram is available. 
   

   
   
   Figure 8. Show reference chromatogram from method icon

2. A REF tag is added to the description of the reference chromatogram.
   • In the Separate display mode, reference chromatograms are always shown at the top. They are shown independently of the signals selected in the navigation pane.
   • Peak and compound annotations are identical to the other chromatograms. However, you cannot select the signal of the reference chromatogram.

Additional Information 

1. To show multi chromatograms in Chromatogram window separately, set Display Options in Chromatogram Properties > Chromatograms settings. (Figure 9)
   

   
   
   Figure 9. Gear icon 

2. Number of panels to display drop-down menu can configure this setting. (Figure 10)
   

   
   
   Figure 10. Display panels 
   
   

Learn how to effectively operate your Agilent OpenLab CDS software:  Agilent 1260 Infinity LC Systems with OpenLab CDS eLearning path available from Agilent education