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The spectroscopic identification techniques consist of Raman spectroscopy and FTIR. These techniques are based on the energy sorption by characteristic functional groups of polymeric materials. Thus, samples must be dried before analysis because water strongly absorbs IR radiation. The purification of samples is important because organic, inorganic–organic, or inorganic may affect the IR spectra of samples. Larger particles (>0.5 mm) may be investigated by FTIR with an attenuated transverse reflection (ATR) unit (Doyle et al. 2011; Klein et al. 2018; Zhang et al. 2015). MPs are manually transferred to the crystal of the ATR unit. The FTIR can be combined with an IR microscope to enhance the identification of small MPs (>10 μm) (Sadri and Thompson 2014). In Raman spectroscopy, the sample is exposed to monochromatic laser radiation. The reaction of the molecules and atoms with the laser radiation cause differences in the frequency of the backscattered light compared with the initial laser frequency. This can be computed to create substance‐specific Raman spectra. Raman spectroscopy is also able to be connected with microscopy. The Raman micro‐spectroscopy can identity very small MPs of sizes down to 1 μm (Yan et al. 2019). Until now, FTIR is widely used in MPs studies.