Microwave-assisted digestion for rapid extraction of microplastics from food matrices

The lack of rapid and standardized digestion protocols for isolating microplastics (MPs) from complex food matrices remains a major bottleneck in MPs monitoring and risk assessment. This study presents a cost-effective and efficient method for extracting MPs from food matrices using microwave-assisted digestion. Five common polymer particles were treated for 30 min using two digestion systems: S1 (8 mol/L HNO 3 ) and S2 (4 mol/L HNO 3 /30% H 2 O 2 , 4:1, v/v). Polystyrene (PS) and polyethylene terephthalate (PET) were more susceptible to digestion-induced alterations, particularly in S1 system, whereas S2 system better preserved their physicochemical properties. Polypropylene (PP), polyethylene (PE), and polyvinyl chloride (PVC) remained stable at 140℃ in both systems. The optimized digestion conditions for representative food matrices were determined. Hypsizygus marmoreus was digested using the S1 system at 80℃, whereas wheat flour, jelly, and ham sausage were digested using the S2 system at 80℃, achieving digestion efficiencies exceeding 98%. Spiking recovery experiments using PP particles of two size ranges (10-200 μm and 500-800 μm) yielded recoveries of 90.94%-103.47%. The proposed microwave-assisted digestion strategy provides a rapid, reliable, and broadly applicable protocol for MPs extraction from diverse food matrices, and facilitates the transition of MPs analysis toward greener and more sustainable analytical workflows.