Organic particles can be identified by infrared spectroscopy (IR). The IR spectrum measured with this method is compared with spectra of typical materials of raw materials, operating and process materials by means of a database search and thus the particle material is identified. In addition, the measured IR spectrum can also be compared with the IR spectrum of the suspected reference material. This allows conclusions to be made about the origin of the organic impurities, such as plastic particles from moulding burrs, impurities from packaging (plastic, cardboard, wood), but also textile fibres. The IR analysis is performed by preparation of single particles onto the ATR crystal of the FT-IR microscope. The result is shown with the particle image of the analyzed particle and the IR spectrum with reference spectrum (database or reference measurement). The definition of the organic substances or substance compound is also part of the result.

However, measurement of the IR spectrum of organic compounds of a particle or fiber requires that the particle is sufficiently large and detectable to be prepared manually from the analysis filter to the ATR crystal.