Practical guidelines and challenges in the isolation and characterization of microplastics/microfibers by Raman microscopy

We address some challenges usually encountered in the analysis of microplastics (MPs) and microfibers (MFs) using Raman microscopy. Those issues are examined considering that the researchers that carry out the collection and analysis of MP contamination may not have necessarily specialized expertise in Raman microscopy or polymer chemistry. Topics such as effective particle isolation or the use of adequate substrates are approached on the base of the impact they have on the spectroscopic characterization. Issues as the control of background signal, the influence of sample digestion, and the presence of internal interferences such as pigments, dyes, and fillers, are discussed. Spectral features of the polymer families found as MP/MF contaminants are presented based upon polymer structure, properties, and applications. The use of open-source libraries to complement chemical identification is also discussed. Overall, this work aims to enhance the practice and understanding of Raman microscopy for researchers engaged in characterizing MP/MF contaminants.