Abstract

In recent years one can observe a significant increase in the requirements on quality control in all industrial sectors. The growing number of involved analyses makes the traditional, time consuming, requiring use of large quantities of reagents, thus expansive methods inconvenient especially for industrial applications. Fortunately, there is a very fast, cheap and not invasive analytical method that is increasingly used in qualitative and quantitative analysis: Near Infrared Spectroscopy (NIRS). NIR spectroscopy is based on the absorption of electromagnetic radiation at wavelength in the range 780-2500nm. The NIR spectrum (signal) is a consequence of the absorbance caused by vibrations of bonds containing hydrogen atom like C-H, N-H, O-H, and S-H. Near infrared spectroscopy has become one of the most powerful techniques in nowadays analytical chemistry, because of its following important advantages : 1) the energy of radiation is small enough to allow a non-destructive and non-invasive analysis of samples, 2) requires minimal or no sample preparation, 3) measurement and result delivery are quite fast, 4) enables the determination of several physical-chemical properties and concentration of chemical compound from a single spectrum, 5) NIR radiation allows the use of long fibre optics, which can be useful for the on-line analysis. These attributes make NIR especially attractive for straightforward and speedy characterization of samples, e.g. on production lines. Like every technique NIR has also some drawbacks. The main difficulty of that technique is that it requires usage of chemometrics to extract relevant information from quite complex analytical data, which may not be a trivial task. NIR based spectroscopy has an amazing spectrum of applications in (among others) following areas: food, petrochemical, pharmaceutical, clinical and environmental sector. The spectrum of NIR applications encompasses selection of apples in terms of their water content, determination of concentration of filters in suntan oils, imaging of the brain activity and many others.

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