Comparing Raman and FTIR Spectroscopy for the Quantification of Microplastics

Microplastics (<5 mm) have become an increasing concern for the environment. These small plastic items can contain toxic ingredients and are assumed to accumulate persistent organic pollutants and heavy metals from the surroundings. Since microplastics are ingested by small organisms, they harbour the risk to propagate with these hazardous substances up the food chain. An environmental risk assessment is highly needed, but currently not possible since reliable data about the amount of microplastics in the environment are lacking. The detection of microplastics poses a challenge in many respects with the analytical investigation as one major issue. The most reliable techniques for the experienced analysis of microplastics are Raman and Fourier-Transform infrared (FTIR) spectroscopy. In this context, two highly promising approaches have been suggested to automate microplastics counting: chemical imaging and single-particle exploring (SPE). In this study, microplastics have been investigated for the first time by combined analysis with µ-Raman, ATR-FTIR, SPE coupled to µ-Raman (SPE-µ-Raman), and µ-FTIR chemical imaging in reflection-absorption mode