Quantification of micro- and nanoplastics

Quantitative analysis of micro- and nanoplastics (MNPs), providing precise, accurate, and reliable data, is necessary to make meaningful contributions to gaining a comprehensive understanding of MNPs fate in the environment. However, while for microplastics both mass-based and particle-based techniques are widely described in the literature, nanoplastics have so far been quantified in environmental samples only by mass-based techniques and together with microplastics. Different proof-of-concept particle-based methods for nanoplastics quantification have been proposed. Here, a critical review of feasible, mass-based, and particle-based quantification techniques for analyzing MNPs from environmental matrices is presented, with a particular focus on nanoplastics. Based on the findings of this review, we can conclude that it is currently not possible to precisely quantify MNPs from the environment using analytical methods presently available, and furthermore, research efforts are necessary.