Metrohm NIRS XDS MasterLab Analyzer - Manual (Page 107)

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The results screen shown above is typical. Peak positions for the reference materials are located using
a peak-finding algorithm. These “found” peaks are compared to the nominals. Differences should be
no more than 0.4nm for any peak. Click “Yes” to send the linearization to the instrument.
After the linearization is successfully sent to the
instrument, this message confirms the transfer.
Click “OK” to proceed.
8.1.2 Reference Standardization, Reflectance, “Use Tray” Position
Reference Standardization is a method to provide a virtual 100% reflectance reference at each data
point, to serve as a true spectroscopic reference with no character attributable to the physical
reference used. This is important to achieve a high-quality spectrum on each instrument, and to
enhance transferability between instruments.
A photometric standard of known reflectivity (as measured on an absolute reflectance scale) is
scanned on the instrument. The internal ceramic standard is scanned. The differences of the ceramic
standard from 100% reflectivity are mapped, and a photometric correction is generated. This
correction is then applied to every spectrum taken on the instrument, to correct each spectrum as if
taken with a reference of 100% reflectance. This assures that bright samples do not saturate the
instrument, or produce negative absorbance values.
The MasterLab Analyzer requires two reference standardizations in reflectance, one for each
sampling level. The first level is with a vial directly on the sample window, using the Iris Adapter. The
second level involves the Tablet tray, where the vial is slightly above the sample window.
To account for the difference in sampling height, the background reference is adjusted using