Extracting Specific Absorbance Signal from 3D IsoPlot with OpenLab ChemStation

Answer

This Information Applies To: Agilent OpenLab ChemStation

Issue

If the DAD full spectrum was saved during the run, it is possible to extract a signal at a different wavelength from the originally acquired in the acquisition method. This article describes how to extract chromatograms at specific absorbance using 3D Isoabsorbance Plot with OpenLab ChemStation Data Analysis software.

Requirements

The samples must be run with the Store: All setting in the advanced section of the DAD tab of the instrument method.

Steps to Follow

1. Launch ChemStation software > go to Data Analysis window and load data including 3D spectrum (Figure 1).
   

   
   
   Figure 1. ChemStation Data Analysis window
   
   

2. From the main menu, click Spectra > Isoabsorbance Plot (Figure 2).
   

   
   
   Figure 2. Spectra drop-down menu
   
   

3. Isoplot window is displayed (Figure 3).

   
   
   Figure 3. Isoplot window
   
   

4. From the Cursor drop-down menu at the upper-left corner window, select Signal (Figure 4).
   Enter the specific value of absorbance WL (wavelength) and BW (bandwidth) at Signal field and Ref (reference) field. You can choose a reference wavelength for suppressing baseline drift.
   

   
   
   Figure 4. Signal selection at Isoplot
   
   

5. Click the Copy button at the bottom-left corner of the window (Figure 5).
   

   
   
   Figure 5. Copy button of Isoplot
   
   

6. click the Exit button at the bottom-right corner of the window to close Isoplot window (Figure 6).
   

   
   
   Figure 6. Exit button at Isoplot
   
   

7. After closing the Isoplot window, if spectral data inside PC memory is still needed, click Yes to keep 3D data at the memory area. If not, click No to discard stored 3D data (Figure 7).
   

   
   
   Figure 7. Closing the Isoplot
   
   

8. After copying the signal from Isoplot, an extracted signal can be displayed at the chromatogram window (Figure 8).
   The signal drop-down menu displays extracted signals.

   
   
   Figure 8. Extracted Chromatogram
   
   

9. Extracted chromatogram could be processed as usual signal data (Figure 9).

   
   
   Figure 9. Process Data for Extracted Signal
   
   

10. To save an extracted chromatogram, from the main menu click View > Windows Functions > Save Window (Figure 10).
    

    
    
    Figure 10. Save Window 
    
    

    Extracted signal can be saved as a data file inside each injection folder (Figure 11).

    
    
    Figure 11. Save Chromatogram to File window
    
    

11. To load an extracted chromatogram, from the main menu click View > Windows Functions > Load Window (Figure 12).
    

    
    
    Figure 12. Load Window
    
    

    Select extracted signals from the Load Windows dialog box (Figure 13).
    

    
    
    Figure 13. Load Window dialog box
    
    

12. Extracted chromatogram is loaded (Figure 14).
    

    
    
    Figure 14. Extracted Signal
    
    

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