Smart filters for the analysis of microplastic in beverages filled in plastic bottles

The occurrence of microplastic (MP) in food products, such as beverages in plastic bottles, is of high public concern. Existing analytical methods focus on the determination of particle numbers, requiring elaborate sampling tools, laboratory infrastructure and generally time-consuming imaging detection methods. A comprehensive routine analysis of MP in food products is still not possible. In the present work, we present the development of a smart filter crucible as sampling and detection tool. After filtration and drying of the filtered-off solids, a direct determination of the MP mass content from the crucible sample can be done by thermal extraction desorption gas chromatography mass spectroscopy (TED-GC/MS). The new filter crucible allows a filtration of MP down to particle sizes of 5 mu m. We determined MP contents below 0.01 mu g/L up to 2 mu g/L, depending on beverages bottle type. This may be directly related to the bottle type, especially the quality of the plastic material of the screw cap. Dependent on the plastic material, particle formation increases due to opening and closing operations during the use phase. However, we have also found that some individual determinations of samples were subjected to high errors due to random events. A conclusive quantitative evaluation of the products is therefore not possible at present.

Automated summary

The study proposes a new method for analyzing microplastics in food products using a smart filter crucible, allowing for direct determination of their mass content. It was found that the type of beverage bottle can affect the microplastic content, especially related to the quality of plastic material in the screw cap, and particle formation increases during use phase operations.