Quantifying the occurrence of polystyrene nanoplastics in environmental solid matrices via pyrolysis-gas chromatography/mass spectrometry

Although polystyrene (PS) is one of the most abundant plastic particles and PS nanoplastics (PS-NPs) have been found in water phase and aquatic organisms, their occurrence in natural solid matrices is rarely reported due to the lack of methods. Herein, on the basis of pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) technique, for the first time a simple and robust protocol was developed for the extraction of PS-NPs to investigate their presence in envi-ronmental solid samples. Parameters of the extraction procedures, including extractant compositions and concen-trations, shaking time, extractant to solid ratio, and pH were investigated with palladium-doped PS-NPs. Then, the optimized procedures were validated to extract and quantify commercial PS-NPs with different sizes spiked in complex solid matrices. Detection limit of 0.02 mu g/g was obtained, and recoveries were 72.5-87.2 % for PS-NPs spiked in environmental solid matrices at levels of 21.6 mu g/g. The method was successfully used for the determination of the indigenous PS-NPs ranging from 0.16 to 0.73 mu g/g in six out of 11 natural solid samples, confirming the previous speculation that environmental solid matrices are important sources and sinks of NPs. Consequently, this study paves new avenue for closely monitoring NPs in environmental solid matrices and evaluating their potential risks.