A procedure to evaluate different techniques for the extraction ofpollutants from plastic debris in the environment

Once entered in the aquatic milieu, plastic wastes will be weathered and fragmented into smaller pieces. While migrating long distance for a long time, these plastic fragments accumulate a variety of pollutants including persistent organic pollutants (POPs) on their surface. For the estimation of ecological impacts of plastic debris in the environment on a range of marine organisms, therefore, it is important to understand the nature and extent of pollutants enriched on plastic debris. A number of methods are reported for the extraction of pollutants from plastic debris. However, it is difficult to compare different techniques or different conditions for the extraction of pollutants accumulated on plastic fragments, mainly, due to a lack of standardized methods for the determination of the efficiency of pollutant-extraction by different techniques. Here, we propose a procedure to evaluate different techniques for the extraction of pollutants from plastic debris in the environment. Firstly, we propose a quick and reproducible method for the production of plastic debris charged by a known amount of pollutants on the surface. The pollutantloaded plastic debris could be used as a reference material to determine the extraction efficiency. Using this quick method, we prepared resin pellets from five different polymer types charged by known amounts of pollutants. Pollutants selected for this study have a range of octanol/water partition coefficients (log Kow) between 3 and 6. Properties of the pellets were determined by CARAT GmbH (Bocholt, Germany). Secondly, we propose a procedure for the evaluation of extraction techniques. Extraction techniques and conditions are to be evaluated for a high extraction recovery, a high reproducibility, as well as for a minimal damage of plastic debris, i.e. carriers of pollutants. Here, we evaluated extraction efficiency by soaking and sonication in different solvents using the resin pellets charged with a known amount of pollutants. The extraction recovery was determined by comparing the extracted mass to the original mass of the pollutant on the pellets. Further, the loss of plastic weight was measured for the evaluation of the stability of plastic particles under given extraction conditions. TU Darmstadt and CARAT are participants of an EU project “PLASTOX”, a consortium of a JPI Oceans’ Joint Action. TU Darmstadt is funded by BMBF.