A reliable analytical method to quantify and characterise microplastics in mussels and clams using gold-coated filters and quantum-cascade laser infrared transflectance imaging (QC-LDIR).

Galicia (NW Spain) is a worldrenowned player in high-quality seafood. Despite being a small region, it ranks second in the world production of mussels (mostly, Mytilus galloprovincialis, ca. 250,000 tons). Mussels are efficient filter feeders and are considered general environmental sentinel organisms making them an important species for assessing microplastics (MPs) in the environment and identifying potential risks. Despite several analytical strategies were developed recently for this objective, progress is still needed to standardise and get an analytical method that can be used in routine laboratories. Here, three of the most common digestion approaches to isolate MPs from the organic matrix of bivalves are studied in mussels: two alkali-oxidative methods, and one enzymatic-oxidative protocol. The latter was the most suitable option, although a two-step alkaline oxidative plus surfactant-oxidative protocol can be a reliable low-cost alternative. A high-throughput measurement based on the use of quantum-cascade laser IR transflectance imaging (QC-LDIR) is proposed utilizing gold-coated filters for direct analysis, after a previous resuspension of the filtrate obtained from a stainless-steel metallic filter. The overall methodology was validated, with recoveries in the 90-97 Also see: https://micro2024.sciencesconf.org/558626/document