Microplastics detection by impact electrochemistry

Microplastic pollution has emerged as one of the major environmental issues affecting aquatic ecosystems. Although the presence of plastics in the oceans has been documented since the 1970s, scientific attention has recently shifted toward small-sized particles (less than 5 mm in size), the so-called microplastics, often smaller than 100 μm. These microplastics originate both from the fragmentation of plastic debris and from the direct release of polymers used in industrial processes. Their concentration, combined with the diversity of polymer compositions and particle sizes, makes their identification and quantification particularly challenging.In this work, we present a novel technique for microplastic detection and characterization based on impact electrochemistry, using the potentiostat of a Scanning Electrochemical Microscope (SECM, CHInstruments). The method is based on the impact between a plastic particle suspended in an aqueous solution and the surface of a microelectrode. The experiments were performed using a three-electrode configuration (Fig. 1a), consisting of a fixed-potential working electrode made of a 10 μm gold tip, an Ag/AgCl reference electrode, a platinum counter electrode, and an electrolyte composed of a NaCl solution with varying molarity and/or different microplastic concentrations.