Sample homogenisation is the only way to guarantee accurate and precise analysis results!
The different properties of ground and unground samples when analysed with NIR are demonstrated with grains of wheat. The samples were analysed 10 times, the spectrometer was refilled for every measurement. The wheat grains were previously ground in RETSCH’s cyclone mill TWISTER.
The results show a considerable difference between ground and unground sample, particularly with regards to ash and fibre content. This is due to the fact that only the surface of the unground wheat grains is analysed resulting in an over representation of the kernel shell.
NIR spectroscopy allows the determination of a series of relevant parameters in feeds and grains without great effort. The prevalent opinion is that sample preparation is not required for NIR analysis. However, the results presented by Retsch clearly indicate that it is beneficial to pulverize the samples with a suitable laboratory mill before analysis, particularly if the material is inhomogeneous. That is the only way to guarantee meaningful and reliable analysis results.