- PDA/DAD chromatogram data viewed as BPI does not show negative values
- BPI trace: TIC trace:
- Photodiode Array Detector (PDA/DAD)
- Base Peak Intensity (BPI) chromatogram display
MassLynx stores BPI data as an unsigned integer. It cannot store or display negative values.
Selected wavelength displays are unaffected.
FIX or WORKAROUND
Do not use BPI if the chromatogram has peaks that drift below the zero baseline. Selected wavelength displays are unaffected.
MassLynx will not be changed to accommodate signed data for BPI.
MS data is not affected by this issue because it is never a negative number.
Set the starting baseline on the DAD as a higher absorbance, or develop the analytical method to reduce the absorbance of the mobile phase (usually B).
If the detector allows, set an absorbance offset, or establish a reset baseline at a point in the run (older detectors only).