Development of a low-cost and rapid detection method for micro- and nanoplastics in beverages and its application

To quantify the release of micro- and nanoplastics (MNPs) from beverages, this study firstly used a pretreatment procedure to fractionate MNPs into two size ranges: >50 and 0.22–50 μm. The larger fraction was analysed using fluorescence microscopy, while the smaller particles were quantified by flow cytometry. The gating strategy and fluorescence staining conditions for flow cytometric analysis were then optimised to achieve clear discrimination between the signal of MNPs and background noise. Finally, this study used standard beads of MNPs to validate that the method achieved a recovery rate of >97%, and we further confirmed that the method can be applicable within pH 3–11. Using the established method, this study systematically investigated the effects of physical and environmental factors during beverage storage and consumption. The results revealed that prolonged storage time, lower temperature, increased freeze-thaw cycles, longer vibration, and higher opening frequency all significantly enhanced MNP release and promoted further dissociation of larger particles. Economic assessment indicated that the method requires approximately 7–8 min per sample, with an analytical cost of about 10.74 RMB per sample, enabling detection of over one thousand samples per month. The developed detection method of MNPs thus offers the advantages of rapidity and low cost, and can be broadly applied to the rapid detection of MNPs in beverage products and to production quality control.