Direct Identification and Quantification of Nanoplastics in Aqueous Environments via Dual-Channel Electrothermal Vaporization-Microplasma-Based Point Discharge-Optical Emission Spectrometry (DC-ETV-μPD-OES)

A miniaturized analytical platform integrating dual-channel electrothermal vaporization-microplasma-based point discharge-optical emission spectrometry (DC-ETV-μPD-OES) has been developed for the direct identification and quantification of nanoplastics (NPs) in aqueous samples. Unlike conventional approaches that rely on time-consuming and potentially loss-inducing pretreatment steps like “filtration-drying”, this system introduces an innovative “evaporation-pyrolysis” dual-channel design, enabling direct introduction and analysis of liquid suspensions. By incorporating a three-way valve and a silica gel drying unit, the platform effectively redirects and removes water vapor, significantly improving plasma stability and analytical reproducibility. Under optimized conditions, the method delivered linear responses (R2 > 0.998) for polystyrene (PS) NPs, poly(methyl methacrylate) (PMMA) NPs, polylactic acid (PLA) NPs, and polyvinyl chloride (PVC) NPs across a concentration range of 5–227 mg C/L, with detection limits between 4.08 and 11.02 mg C/L. Machine-learning-assisted classification─particularly using the k-nearest neighbors (KNN) algorithm─achieved 100% accuracy in polymer discrimination based on spectral fingerprints. Analysis of spiked environmental water samples yielded recoveries (84.6–109.1%), confirming the method’s reliability for real-world applications. This work establishes a portable, low-energy-consumption alternative to conventional laboratory-based techniques, offering a practical and promising tool for on-site screening and quantification of NPs in aquatic environments.