Detection of micro- and nanoplastic particles in leafy green vegetables by SERS coupled with gold-silver core-shell nanoparticles

A sensitive and accurate method has been developed for detecting and quantifying polystyrene (PS) and polyethylene (PE) in food samples using surface-enhanced Raman spectroscopy (SERS) with a simple preparation process. The method is designed to effectively detect and quantify mixtures of these polymers in varying ratios within the food matrix. By employing gold-silver core-shell nanoparticles (Au@Ag NPs) as the enhancing substrate, the SERS method demonstrated superior sensitivity in detecting trace amounts of micro- and nanoplastic particles (MNPs). For 1-µm PS microparticles, the limit of detection (LOD) values range from 12 to 50 mg/L or mg/kg in water, spinach, and kale, while for 100-nm PS nanoparticles, the LOD values range from 18 to 47 mg/L or mg/kg. For 1-µm PE microparticles, the LOD values range from 173 to 416 mg/L or mg/kg in the same matrices, whereas for 65-nm PE nanoparticles, the values range from 446 to 744 mg/L or mg/kg. The mixtures of PS and PE in varying ratios were also tested, with both plastics detectable even at trace levels, emphasizing the method's precision in detecting plastic contaminants. These findings highlight the potential of SERS as a powerful tool for monitoring MNP contamination in food products by detecting both individual plastics and their mixtures, enabling precise quantification of contamination and contributing to improved food safety.