Analytical challenges for detection and determination of small microplastics in food samples

Microplastics (MPs) represent a growing concern as pollutants of anthropogenic origin, prompting the European Commission to advance legislation aimed at mitigating their potential risks to human health and the environment. To support effective decision-making and pollution control measures, there is a need for reliable, traceable and standardized methods for particle analysis that can provide consistent and comparable data. One of the main analytical challenges lies in detecting small microplastics (SMPs, 10-100 μm) in complex matrices, which often contain high levels of organic matter, without compromising particle integrity or altering polymer composition [1]. The present study focuses on the development and validation of a robust analytical approach for the chemical identification, physical characterization, and quantification of SMPs in drinking water and milk powder (infant formula) using Environmental Scanning Electron Microscopy (ESEM) [2] and µ-Raman spectroscopy. To maximize the impact of the research, both primary polystyrene and secondary polyethylene terephthalate particles were chosen as representative test materials. Preliminarily experiments on blank samples were carried out to establish best practices for clean room operations and procedures to minimize cross-contamination throughout the analytical process. A filtration system with 5 μm silicon filters was selected, achieving particle recovery between 85 and 120%, depending on particle size and the characterization technique. Additionally, different strategies for isolating SMPs from organic and inorganic matrix components were explored, including oxidative digestion and multi-enzymatic treatments combined with microwave-assisted alkaline hydrolysis [3]. Future work will include the analysis of real-world samples and participation in inter-laboratory proficiency testing as part of the ongoing funded project. REFERENCES [1] Kadac-Czapska K et al., Food Chem., 440 (2024), 138246. [2] Piergiovanni M et al., Molecules, 29 (2024), 3148. [3] Da Costa Filho PA et al., Sci Rep., 11 (2021), 24026