Single-particle analysis of micro/nanoplastics by SEM-Raman technique

Micro/nanoplastics (MNPs) have received global concern due to their widespread contamination, ingestion in organisms, and the ability to cross the biological barrier. Although MNPs have been detected in a variety of ecosystems, the identification of single MNPs remains an unsolved challenge. Herein, for the first time, scanning electron microscope (SEM) coupled with surface-enhanced Raman spectroscopy (SERS), which combined the advantages of ultrahigh spatial resolution of SEM and structural fingerprint of Raman spectroscopy, was proposed to identify MNPs at single-particle level. Under the optimum conditions, the polystyrene (PS) MNPs with sizes of 500 nm and 1 μm were identified by the image of SEM and fingerprint peaks of Raman spectroscopy. Additionally, the applicability of the method in different sample matrices and for other types of MNPs such as poly-methyl methacrylate (PMMA) with the sizes of 300 nm, 1 μm were validated. This method is simple, rapid and effective and is likely to provide an essential tool to identify other micro/nanoparticles in addition to MNPs.