A critical review of the novel analytical methods for the determination of microplastics in sand and sediment samples

Microplastics (MPs) form the most investigated plastic category since their size (1 μm- 5 mm) enables them to accumulate in various environmental compartments and to be ingested by biota. Beach sand and sediment can be indicators of the MP contamination levels of the coastal and marine ecosystem and, thus, they are widely analyzed. With the increasing number of publications in recent years, there is a need for constant updates on the variety of extraction and analysis procedures developed. Thus, this review aims to evaluate the sample preparation techniques for MPs and provide a critical discussion on their determination in sand and sediment based on studies published in the last 5 years. We also report the conditions imposed by the MPs identification and quantification techniques on sample preparation and MPs isolation as well as the materials used in the procedures. Finally, we address the expectations and new challenges related to instrumental innovations.