Metrohm NIRS XDS Interactance OptiProbe Analyzer - Manual (Page 63)

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consistent over time. Note that both tests use the wavelength standard at the sample plane, where
actual sample measurement is done.
Performance Test measures peak positions of internal reference materials, and these positions are
used as a method to maintain wavelength measurement at the sample plane, using the external
standard. As discussed under Performance Test, the internal reference materials are not traceable,
and are only used as an internal method of maintaining correct wavelength measurement on the
external wavelength standard.
In the event that the instrument passes Wavelength
Certification on the NIST-defined peaks, but fails on the
FOSS-defined (tighter) peaks, this message may be
displayed.
This is not a failure; it is a message that the Instrument
Calibration peaks have drifted slightly and should be re-run.
This could be due to ambient temperature issues with the
WSR, or drift due to other causes.
Re-run Instrument Calibration, then run Wavelength
Certification again to verify that it has passed.
7.2.3 Photometric Test
Photometric Test provides a method to verify ongoing photometric performance of the instrument.
This is a requirement for pharmaceutical users. Test results are stored in the Diagnostic Database, and
may be accessed at any time. Control charts are plotted (after several tests have been stored) to
provide an ongoing record of performance.
The test uses the same standards used in IPV Setup. Photometric Test compares current spectra of
each standard to those stored during IPV setup. If any differences exceed normal tolerance values,
the instrument can be assumed to have changed in some manner, and may need service.
Because the calibrated photometric standards are the link to previous photometric performance, the
standards should always be stored in their wooden box, and protected from fingerprints, dropping,
or other damage. If any cup is opened, dropped, or otherwise altered, Photometric Test results may
fail.
To run Photometric Test, select it from the
Diagnostics menu.