Structure – Interdisciplinary topic “sampling” 
Sampling is the first step in the analysis. It is usually conducted in the field but some samples will also be taken during laboratory experiments, however these samples will have different sizing. From experience, sampling is generally the most error-prone step in the analysis, since most of the surveyed systems are very heterogeneous. Sampling is not oriented towards further sample preparation or detection but towards the sampled medium or the examined material. Therefore, sampling techniques differ between aqueous and solid phases. Considering the relevant matrices within the current project, a variety of sampling techniques with specific focuses has been developed in the recent past. They are now being tested, assessed, and further developed if necessary, with respect to their feasibility for microplastics analysis. Essentially, sampling must be representative for the examined medium or material. This field will be covered notably by the sub-projects within project section A. Water sampling will focus on matrices in urban areas such as treated wastewaters, rain water, combined sewer overflows and urbanized surface water sections upstream and downstream of discharge points, groundwaters, and raw and drinking waters. At these sites, sampling of sediments is planned, too. The upper and younger sediment layers are particularly important and interesting.