Metrohm NIRS XDS Process Analyzer – MicroBundle - Manual (Page 85)

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These peak positions are not meant to be
traceable, as the wavelength calibration of the
instrument is done on an external standard,
traceable to NIST.
The internal wavelength standards are used to
maintain the external wavelength registration
by use of software adjustment for any
external effects on the instrument.
Select Wavelength Linearization from the
Diagnostics menu. The instrument will scan
the reference, which is the fiber optic that
runs from the monochromator to the detector
area inside the instrument.
Peak positions for the reference materials are located using a peak-finding algorithm. These “found”
peaks are compared to the nominals. This is done twice, one for each direction of the grating
motion. No operator interaction is required.
After the linearization is successfully sent to the instrument,
this message confirms the transfer.
Click “OK” to proceed.
10.4.2 Reference Standardization, Transmission Probes
Reference Standardization with Transmission Probes uses an innovative means to adjust each channel
to a repeatable, transferable level of spectroscopic response. The fiber ends are placed into a fixture,
the response is measured, and the signal is “normalized” using a spectral correction.
This shows the fixture. When Reference Standardizing, this
fixture holds the two probes in alignment, at a pre-determined
distance.
The optical response of the air gap is measured and stored. A
correction is applied, to bring the channel to “0 Absorbance” in
transmission, corresponding to the response of an air
reference.
This fixture is also used in Instrument Calibration.
Follow these instructions to perform Reference Standardization:
1. Insert each probe into the fixture as shown.