**1. Introduction**

This chapter presents a reliable method for preparing standard microfilaments to facilitate lab testing and monitoring of microplastics in different matrices. The scope is to achieve a positive impact on the quality control of all operations, from sampling to counting and identification. Using standard synthetic microfilaments as references for the validation of common experimental procedures could reduce differences between data. Furthermore, a standard synthetic fiber material would allow the monitoring of the ecotoxicological impacts of microplastics on biota and human health in line with the European Commission's Green Deal, the Circular Economy Action Plan and the proposed remedial actions supported by the U.N SDGs under Goal 14.
