BRUINS INSTRUMENTS. Training Near Infrared Transmission Whole Grain Analyzer. Targets:. History and Basics of NIR Calibration development Toubleshooting & Maintainance. History of NIR. First detected by William Herschel beginning of 19th century
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Near Infrared Transmission
Whole Grain Analyzer
NIR = Near InfraRed Spectroscopy
Wavelength of Light
UV > VIS > NIR >(M)IR
nm 380 750 / 1100 2500
(NIT / NIR)
Energy of Light
Typical properties analysed by NIR are
organic compounds like
Useful concentration are in % range,
ppm or ppb level are normally impossible.
O-H Water, Alcohol
C-H Carbohydrates (Starch, Sugar, Cellulose)
Fat / Oil
In all cases, if fine powder or ground sample:
If a micro sample cup is used:
Before using the instrument in routine, it must be compared against the reference method with a set of samples.
These samples should cover the range of concentrations and normal variations in moisture, area and genotypes.
In order to get a good adjustment, the sample must be well mixed that the same material will be analysed with both methods.
The data for the reference analysis need to be well controlled, at least a double analysis must be performed.
The easiest comparison of accuracy and necessary adjustment can be made with Excel.
Just two columns need to filled , one with reference analysis the second with predicted NIR data.
Using the Excel functions for mean, standard error xy and correlation will calculate all necessary information.
Additional the Excel graph can be used to show how good the predicted values fit to the reference analysis.
While the bias will move all data parallel, the slope will change the extreme values more than the values around the middle.
So adjusting the slope will much more influence the predicted result.
For the slope adjustment the sample set must really cover the full calibration range.
Normally this adjustment should not be used. If it seems to be necessary, look for the reason. It might be better to select or built another calibration.