Marta Barbaresi, Maurizio Piergiovanni, Matteo Masino, Federica Bianchi, Monica Mattarozzi, Maria Careri

Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale, Università di Parma, 43124 Parma, Italy

Microplastics (MPs) are emerging anthropogenic pollutants, for which the European Commission is driving the development of legislation needed to tackle their potential threat to human health and the environment. This requires traceable, harmonized and quality-assured methods for particle analysis to obtain consistent and inter-comparable data, thus supporting decision-making and mitigation measures related to plastic pollution. As for analytical challenges, small-microplastics (SMPs, 10-100 μm) are difficult to isolate, enrich and detect in matrices with high concentrations of organic compounds, without compromising the integrity of the particles and altering polymer composition [1]. In this context, the present study focuses on the development and validation of an analytical approach for chemical identification, physical characterisation and quantification of SMPs in drinking water and milk powder (infant formula) based on the use of Environmental Scanning Electron Microscopy [2] and µ-Raman spectroscopy. To maximize the impact of the study, we considered both primary and secondary particles of polystyrene and polyethylene terephthalate, respectively, as representative test materials. At first, blank filtration experiments were performed to establish good practices to be implemented into a clean room and develop cleaning procedure to minimize cross-contamination throughout the analytical process. Suitable filtration system and filters (Si, 5 μm) were selected to maximize particle recovery, ranging from 77 to 90 % depending on the particle size and downstream characterization technique. Concerning the SMP isolation by selective removal of matrix organic/inorganic matter that inhibit microplastic detection, different approaches for the digestion of organic matrices are being tested, based on oxidation reaction and multi-enzymatic digestion in combination with microwave alkaline hydrolysis. Further activities such as the analysis of real samples and the participation to inter-laboratory testing schemes are scheduled as a final part of the funded projects.

Acknowledgements: Plastic Trace Project JRP-EURAMET Call for Needs 2021-Green Deal. Project funded under the National Recovery and Resilience Plan (NRRP), Mission 4 Component 2 Investment 1.3 - Call for tender No. 341 of 15/03/2022 of Italian Ministry of University and Research funded by the European Union – NextGenerationEU Award Number: Project code PE0000003, Project title “Research and innovation network on food and nutrition Sustainability, Safety and Security – Working ON Foods” (ONFOODS). Keywords: small-microplastics, particle isolation, Environmental Scanning Electron Microscopy, µ-Raman spectroscopy References 1. Kadac-Czapska K, Jutrzenka-Trzebiatowska P, et al., Food Chem., 440 (2024), pag. 138246. DOI: 10.1016/j.foodchem.2023.138246 2. Piergiovanni M, Mattarozzi M, et al., Molecules, 29 (2024), pag. 3148. DOI: 10.3390/molecules29133148