Metrohm NIRS XDS Process Analyzer – MicroBundle - Manual (Page 73)

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high-quality spectrum on each instrument, and to enhance transferability between instruments.
When using the Interactance Immersion Probe, Reference Standardization
is performed using an Interactance Reflectance barrel. Following all
calibration steps, the Interactance Reflectance barrel is removed, and the
Interactance Immersion barrel is installed. A final “Window Correction” is
performed, which adjusts the optical response to the Interactance
Immersion configuration. This provides a reliable method of calibration,
without requiring that the probe barrel be removed from pressure vessels
or reactors. Window Correction is performed only at initial set-up, and is
considered a constant correction factor thereafter.
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 Immersion.
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. 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.