BUCHI NIRCal - Manual (Page 89)

Chemometrics
NIRCal 5.5 Manual, Version A 89
It is possible to save or print this list by clicking on the appropriate buttons.
The ten best calibrations are kept in the project. The calibration with the highest Q-Value is set active.
For this calibration the results are summarized using the Overview. It is possible to inspect the active
calibration manually.
NOTE
It is the responsibility of the user to judge the calibrations and to release them for routine use. The Q-
Value is one among other helpful tools for the judgement of the quality of the calibrations.
It is important to test the calibration with independent well characterized samples
3.5 Pretreatments
3.5.1 Pretreatments
NIR spectra are influenced by various parameters. Variations of chemical and physical properties of
samples as well as the measurement process and changes at the spectrometer will have an influence
on the spectrum. These effects will mainly appear as problems with:

overlapping absorption bands;

non-linearity;

light scattering;

random noise;
One possibility to overcome these problems is to improve the signal by mathematical transformations
of the spectra using pretreatments. They are used to improve the quality of the spectra and to
minimize unwanted effects.
NOTE
Pretreatments do not change or affect the original spectra.
NIRCal provides a variety of data pretreatments, there are 34 pretreatment possibilities available in 6
groups. Each pretreatment can be combined with another and the order of combination is also
important. Some pretreatments, which have a star "*" behind the name, are wavelength dependent. In
this way there are a hugh number of combinations available. The size of a pretreatment sequence is
only limited by the memory.
NOTE
According to our experience it is not suggested to use more than 3 pretreatments. Be aware of
trashing your data to nonsense by misusing pretreatments.
Applying Pretreatments
The pretreatment selection is available in the Menubar: Calibration / Pretreatments.