If you run the detector continuously, Waters recommends that you perform wavelength verification weekly.
The PDA detector's calibration is verified using two spectral peaks from the deuterium lamp and three absorbance peaks from its integrated erbium filter. Upon startup, the detector verifies calibration by comparing the locations of these peaks with expected wavelengths based on calibration data stored in the detector's memory. If the results of this verification differ from the stored calibration by more than 1.0 nm, the detector displays a Wavelength Verification Failure message. See Calibrating the PDA detector.
Wavelength verification typically requires a clean optical path through the flow cell to ensure that the signal is transmitted to the sensor. A flow cell that has been idle for some time may have bubbles or contaminants present that can obstruct the light path and interfere with wavelength verification. For safety purposes, flow is not initiated on instrument startup. If wavelength verification fails at startup, Waters recommends that you rerun the verification workflow with the flow cell flushed and with the flow equilibrated. See Verifying the PDA detector's calibration.
In the event that subsequent verification fails, you can recalibrate the PDA. Note that recalibration can invalidate spectral library matching and the peak purity analyses performed with a prior calibration.
PDA detector features
