Metrohm NIRS XDS Process Analyzer – DirectLight/NonContact - Manual (Page 64)

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After the linearization is successfully sent to the
instrument, this message confirms the transfer.
Click “OK” to proceed.
11.1.2 Reference Standardization, Interactance Reflectance
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 that is used. This will minimize spectroscopic differences between the sample fiber lengths.
Reference Standardization is important to achieve a high-quality spectrum on each instrument
channel, 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 instrument standard is scanned. The differences of the instrument
standard from 100% reflectivity are mapped, and a photometric correction is generated. This
correction is then applied to every spectrum taken on the sample channel, to make each spectrum
appear as if taken with a reference of 100% reflectance. This assures that bright samples do not
saturate the instrument, or produce negative absorbance values.
Vision software stores the Reference Standardization file, which is downloaded to the instrument,
and is applied as a correction to each spectrum.
Note that Reference Standardization must have been selected under Configure, Options, for this to
take effect. Once selected, a new Data Collection Method (DCM) must be created for Reference
Standardization to be checked in the DCM box. It is not applied to a DCM retroactively.
When Reference Standardization is selected under Configure, Options, a Reference Standard must be
created for every sample channel that is “Used” even if the probe style is not Interactance
Reflectance. See the sections on these probes for full information.
Follow these steps to create a Reference Standardization on channels using Interactance Reflectance.
First select the channel. From the menu bar, click
on Acquire, then Select Channel. Use the spinner
to select the correct channel, then click on “OK”.
This must be performed for each channel that is
used. Always verify the channel before proceeding
with the test.
Select Diagnostics, Reference Standard, Create Reference Standard.
Vision takes an instrument reference scan.
The XDS instrument has an internal reference fiber, which is selected for this operation.