How can you make a PDA wavelength that is positive in absorbance negative in absorbance. - WKB106808

OBJECTIVE or GOAL

In some instances you may want a negative PDA wavelength absorbance peak to be displayed as a positive peak, or a positive peak absorbance to be displayed as a negative (mirror plot).

This procedure will show you how to reverse the peak direction using Empower 3 and a PDA detector.

ENVIRONMENT

• Empower 3
• Empower 2
• Empower 3 Personal
• Empower 3 Workgroup
• Empower 3 Enterprise
• 2996 PDA Detector
• 2998 Photodiode Array Detector
• ACQUITY UPLC PDA Detector
• ACQUITY UPLC PDA eλ Detector

PROCEDURE

Text instructions below

1. In the Empower Project - Make sure the Instrument Method is setup to collect 3D data.
2. Edit the Method Set. In the Method Set select:

• Derived Channel - New - Derived Channel First Channel enter PDA Single Wavelength: enter in the desired wavelength
• Select 2nd Channel and in the Operator select * and for the Constant select -1.000
• Save the derived channel as  (selected wavelength_negative)  
• Save the Method Set.

3. Acquire the 3D Data in the Run Samples window

4. Option A

• Highlight the 3D PDA Channel and select the Review window
• Select File - Open Method Set and then select Apply Method Set.
• The Review Window will display the channel in the opposite direction from how it was acquired,

5. Option B

• Select the Sample Set, Injection or Channel view
• Right Click and select Process
• Select use selected Method Set and select Ok.
• Select the Results tab and highlight the processed results
• Select Review or Preview and the reversed direction chromatogram should be displayed.

ADDITIONAL INFORMATION