Quantification of microplastics: Which parameters are essential for a reliable inter-study comparison?

Inconsistencies in microplastic quantification are a problem in current microplastic research, leading to difficulties in inter-study comparability. This study proposes a guideline for consistent quantification of microplastic distributions. It contains specific recommendations on how to quantify common microplastic particle parameters, such as size or shape. These recommendations are based on how reliably a parameter can be measured and its importance for inter-study comparability. Furthermore, our study proposes a multidimensional vector approach, where one vector contains the information for the microplastic distribution in one sample. In this way geometric and statistical means can be used to quantitatively compare different studies. In particular, in combination with our proposed quantification procedure, a meaningful comparison of microplastic distributions across different studies becomes possible. Ultimately, this allows comparable long-term and global scale assessments, as well as the development of modeling approaches.