Microplastics (&lt; 5 mm) have become a major environmental problem worldwide. A fundamental problem in identifying and quantifying microplastics is the difficulties in extracting microplastics from its surroundings. Current methods for extracting, quantifying and characterizing microplastics from sediments lack standardization and accuracy. The differences in methods also makes it difficult to compare microplastic quantities between studies.<br/><br/>Commonly used sediment separation devices include separatory funnels or graduated cylinders, followed by filtration devices. The transferring of samples between glassware and the loss of microplastics on the edges of filtration devices has greatly reduced recoveries in previous studies. Furthermore, the presence of organic matter in a sediment sample makes it especially difficult to isolate microplastics. Four protocols are commonly used to remove organic material during extraction including Fenton’s reagent, H2O2, NaOH, and KOH. These methods can damage the microplastics, potentially leading to the loss or misidentification of the microplastics.<br/><br/>Our objective is to design an accessible and affordable sediment density separation device (DSD) to optimize and harmonize research in the microplastics community. A DSD was built using easily available, inexpensive sight glasses (1.5 in diameter) and valves made from glass and stainless steel. When a vacuum is applied to the sample, cells in the organic material lyse and become waterlogged, causing the material to become more dense and sink. By applying a vacuum to the sediment inside the DSD we are able to greatly reduce the amount of floating organic matter after density separation, which has the potential to greatly increase microplastics recovery. All steps of the density separation process until the filtration step can be done in the DSD, reducing the amount of transfers of the sample thus reducing sample loss. A deep-sea sediment sample will be spiked with particles between 50 and 300 um of 8 polymers in triplicate. Tests will statistically compare the recovery and purity of the microplastics (mass of plastics and organic matter on filter) from the DSD with and without vacuum. Results will be presented.

Separation of microplastics from sediment: A feasibility study

ACS Spring Meeting 2021

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