Quantitative and sensitive analysis of polystyrene nanoplastics down to 50 nm by surface-enhanced Raman spectroscopy in water

Despite being an emerging risk to the environment and human health, little is known about the occurrence, formation, transport, and environmental impact of nanoplastics owing to the lack of quantitative and sensitive sensing techniques. Herein, a surface-enhanced Raman spectroscopy (SERS) method was developed for quantitative sensitive nanoplastics analysis, in which KI was added to Ag nanoparticles as a coagulant and cleaner to remove surface impurities. Polystyrene (PS) nanoplastics with four sizes (50, 100, 200, and 500 nm) were used to evaluate the proposed method, which exhibited high sensitivity (detection limit of 6.25 μg/mL for 100 nm PS nanoplastics), interference resistance, good repeatability, and quantitative analysis ability (R2 > 0.970). The feasibility of extending the proposed method to real-world water samples was verified using spiked lake water, and satisfactory recovery rates (87.5-110%) were obtained for nanoplastics with different sizes and concentrations. Thus, this study serves as a solid step in the quantitative analysis of nanoplastics, and the findings can be applied to other areas of research on nanoplastics.