Description of NIR spectroscopy
NIR stands for near-infrared and means that only light with a wavelength of between 3 µm and 780 nm is used for measuring. A measurement based on infrared light is extremely fast, non-destructive and harmless. This modern form of analysis makes use of the physical attribute that light and materials interact with one another. To be more precise, NIR light causes vibrations in the chemical bonds in molecules. These vibrational excitations are as characteristic as a fingerprint for every sample which is examined by means of NIR spectroscopy, and are presented as a "spectrum". In this it is not only the chemical attributes which play a part, but also the physical state of the particles from which the sample is made up. In principal, therefore, any chemical and physical parameters can be determined through NIR spectroscopy. However, the correlation between the spectrum and the value to be determined (e.g. the sugar content of an apple or its acidity) must be established. Establishing this correlation is the greatest challenge for the analyst attempting to develop an analytical method in this way.
Nowadays, however, with the aid of modern, computer supported data analysis procedures which are capable of solving multivariate problems in multidimensional spaces, we have the necessary tools to hand. NIR spectroscopy enables the simultaneous determination of multiple parameters from a single measurement. In this case we can talk about genuine "green science", since the energy requirements for an NIR measurement are low, no solvents or chemicals are used and the sample is not destroyed. If, for example, a plum is analysed, it can be eaten afterwards without the least concern; after all, it has merely been exposed to harmless infrared light for a matter of seconds.
For a number of years now hand-held, battery-operated NIR spectrometers have been available, which make both measurement and evaluation in situ possible. This enables the user to take full advantage of this type of analysis easily and with no prior experience, no matter where he is.
Some facts about NIR spectroscopy
- Real “green science” due to the fact that no chemicals and solvents are needed. Even the energy demand is very low.
- Measurement by non-destructive infrared light.
- Fast and easy to handle
- Miniaturised hand-held spectrometers available
- Simultaneous determination of multiple parameters in only seconds
- In- on- and at-line applications are possible