2998 Photodiode Array Detector: What is the reason why some devices can extract the 220.0 nm chromatogram from the data acquired in the range of 220.0-400.0 nm and some devices cannot? -WKB

ENVIRONMENT

• 2998 Photodiode Array Detector
• Empower 3
• Wavelength: 220-360nm / Extracted wavelength: 220nm / Resolution: 1.2nm
  One 2998 can extract at 220nm but another 2998 cannot (only 220.6 nm has data, and 220.0nm cannot be extracted).

ANSWER

This is because the wavelength assigned to each diode is slightly different due to erbium calibration.
The 2998 detector has an operation called erbium calibration, which is a function used for checking wavelength accuracy.
As a result, a total of 512 diodes are assigned wavelengths of 190-800 nm.
Dividing 610nm by 512 gives a result of 1.19xxx, so the setting for the highest instrument method resolution is 1.2nm.
However, since the actual wavelength increment is not an integer,
the signal from this diode is specified as a slightly different wavelength even though the hardware is the same (for example, the 200th diode).
Therefore, the actual wavelength may be 220.x nm or 219.x nm instead of 220.0 nm under the 1.2 nm resolution.
At 219.x nm, you can extract 220.0 nm data from 3D data.
Due to this difference, even if 220 nm is similarly specified as the start point of the scan range, it is possible that one detector can only extract at 220.6 nm
while another detector is able to extract at 220.0 nm.
When extracting at 220.0 nm, specify a wavelength below 220 nm, such as 215 nm as the starting point.

ADDITIONAL INFORMATION