Olive oil-based method for the extraction, quantification and identification of microplastics in soil and compost samples

Microplastics (MPs) have become a pressing environmental concern over the past few years and their extraction from solid samples is a scientific challenge that needs to be faced and solved. Standardized and validated protocols for MPs extraction are lacking and the existing methodology, such as density separation, is often unable to separate high density polymers. The aim of our research was to develop a non-density based, inexpensive, simple and safe method to extract MPs from soil and compost samples. We tested an oil-based extracting technique exploiting the oleophilic properties of plastics. For validating the method, soil and compost samples were spiked with six different micro-polymers: polyethylene, polystyrene, polyvinyl chloride, polycarbonate, polyethylene terephthalate and polyurethane. The obtained results are promising, and the polymer density had only a small role in the recovery rate: low, medium and high density polymers reached a mean recovery rate of 90% ±2%, 97% ± 5% and 95% ± 4%, respectively. [Display omitted] •A methodology for microplastic extraction from solid samples is suggested.•Olive oil was selected to extract microplastics from soil and compost samples.•The developed method is able to extract high density polymers.•High recovery rate of 90% ±2% to 97% ± 5% were achieved.•Olive oil seems to have high affinity for a wide set of polymers.