Upgraded Protocol for Microplastics’ Extraction from the Soil Matrix by Sucrose Density Gradient Centrifugation

As land plastic pollution has piled up in recent decades, small products of its degradation, microplastics (MPs), have emerged as a rapidly growing problem in soil environments. The first step in MP evaluation from soils is the extraction of MP particles, and it appears to be a particularly difficult substrate to work with. Aggregate formation and the presence of other organic particles of similar sizes appeared as challenges in constructing an efficient and trustworthy protocol for MP extraction from soils. Density separation-based methods are usually applied and finding efficient cost- and environment-friendly solutions is of high importance, while data comparability is a key factor in increasing general knowledge on the topic. Here, we propose an environmentally friendly protocol based on density separation using sucrose solution. Its efficiency for MP extraction from soil was tested and validated. Protocol validation showed that its use in the extraction of PE was efficient for all examined MP sizes (>32 μm) and PVC >500 μm with high recovery rates, while the extraction of PVC >125 μm is justified since sucrose solution is practically cost-free and completely environmentally safe. Result validation indicates that the proposed protocol has high potential for MP extraction from difficult soil samples.