Isopycnic ultracentrifugation - A promising approach to extract and resolve microplastics from environmental samples

Aileen Jakobs1, Elif Gürkal1, Anja Ramsperger2, Martin Löder2, Tillmann Lüders1
1 Ecological Microbiology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany
2 Animal Ecology I, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany

P 5.3 in Open Poster Session

The increasing accumulation of microplastics (MP) in environments worldwide is considered as one of the most important challenges of our times. MP contamination can lead to alterations in abiotic and biotic processes and even cause negative impacts on ecosystem services. Reliable extraction and detection methods are essential for both determining the extent of MP pollution and for assessing ecological risk. However, extraction of MP from complex environments, such as soils, remains a difficult task. Today, a density-based extraction of MP from environmental samples with saturated salt solutions is widely applied practice, but does not allow to separate MP particles according to their specific density or plastic type. Here, we propose the use of a new isopycnic ultracentrifugation approach as a technique for the fractionated extraction of MP mixtures via density gradients. Diffusion-based density gradients were prepared using high-density CsCl media, with a sufficient density range to separate common polymer types incl. PA, PBAT and PET. We observed that mixtures of pristine, unweathered MP particles showed clear banding patterns at expected buoyant densities, and assume a type-pure separation and fractionation of these particles. Our ongoing work now tests, how weathered MP with an established biocorona behave in isopycnic resolution. If successful, our method can offer a valuable novel approach for the simultaneous extraction and fractionation of various MP polymer types from environmental matrices. 



Keywords: soil pollution, microplastic extraction, isopycnic density separation, ultracentrifugation