Metrohm Vision – Diagnostics - Manual (Page 26)

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Reference Standardization
Reference Standardization is used in reflectance, with all laboratory instruments and all XDS process
instruments. The purpose of Reference Standardization is to minimize any differences in
instrument-to-instrument response that could be attributed to differences in the reflectance reference
material supplied with the instrument.
To use the Reference Standardization feature, the user must go to Options and click on Reference
Standardization. All new Data Collection Methods (DCMs) created for this project will be reference
standardized. This can be verified when a DCM is created and the Reference Standardization box in
the upper right of the DCM screen is checked.
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. Reference Standardization should always be used when
working with an XDS analyzer.
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 make each spectrum appear
as if taken with a reference of a 100 % reflectance. This assures that bright samples do not saturate
the instrument, or produce negative absorbance values.
Vision software stores the Reflectance Standard file, which is downloaded to the instrument, and is
applied as a correction to each spectrum. Please refer to the Installation and User manuals on how to
perform Reference Standardization on XDS Process Analytics Instruments.
To set the “Options” for a given Project, click on Configure, Options.
Instrument must stabilize before data acquisition:
This prevents spectral acquisition if the instrument is
cold.
Performance Test must pass before data acquisition:
This prevents the user from taking data on a
non-functional instrument.
Run performance test after wavelength linearization:
Forces user to run tests sequentially. This is not
necessary with XDS, but may be used for other
models.