Potassium carbonate (K2CO3) – A cheap, non-toxic and high-density floating solution for microplastic isolation from beach sediments

Beaches are good indicators for local microplastic distribution and pollution. Multiple methods have been developed for extracting microplastics from sediment through density separation. However, the chemicals applied are often expensive and harmful to the user or the environment. We briefly review the problems associated with the use of these chemicals and present a new floatation medium, potassium carbonate (K2CO3), that has many advantages over other available media. It is non-toxic and cheap, and with a density of 1.54 g/cm3 the K2CO3 solution yielded a mean recovery rate of around 90% for PVC, one of the densest polymers, that cannot be easily extracted with alternative floatation media. We propose that the use of K2CO3 is particularly promising for long term and large-scale monitoring studies, because it allows involving citizen scientists in such studies, leading to an increased public awareness of the plastic problem in the seas. •Potassium carbonate (K2CO3) is a novel floating solution for microplastic isolation from beach sediments•With a density of 1.54 g/cm3, K2CO3 can extract the most abundant polymers•Potassium carbonate yielded a mean recovery rate of around 90% for PVC, one of the densest polymers•K2CO3 is non-toxic and cheap and particularly promising for long term and large-scale monitoring studies.