In the context of process optimizations for compliance with the acceptance criteria defined in the risk-based approach, further information may be required for the cause research in order to narrow down the source of particles. Here, the material identification of the particles helps decisively in the cause research.

Various analytical methods of inorganic or organic particle materials are available for material identification. The prerequisite for these test methods is the extraction of the particles from the test specimen and the suitable filtration and preparation of the particles for the subsequent analysis.

Anorganic particles are analyzed by SEM/EDX analysis as a combined method for electron-optical counting and measurement of the particles in the scanning electron microscope (SEM) and elemental analysis by energy-resolved X-ray spectroscopy (EDX). The elemental analysis provides as essential information the EDX spectra, which reveal the chemical elements or alloy composition of the particles and thus allow conclusions to be drawn about the origin of the particles.

Organic particles (e.g. curd, cardboard layers, wood, textile fibers) can be identified by infrared spectroscopy (IR). The IR spectrum measured with this method is matched with spectra of typical materials of works, operating and auxiliary materials via database matching, thus identifying the particle material. In addition, the measured IR spectrum can also be matched with the IR spectrum of the suspected reference material.