Portable SERS platform for electrocoagulation and quantitative analysis of microplastics in aquatic environments

Microplastics are emerging pollutants in aquatic systems that cause environmental and health threats and the detection methods are significantly important to guide the proper removal and degradation. However, rapid, sensitive and field-adaptable methods for microplastics analysis remain challenging. In this study, an electrocoagulation-assisted portable surface-enhanced Raman scattering (SERS) workflow was developed for the enrichment and detection of microplastics in aquatic matrices. Electrocoagulation was employed as a pre-concentration to recover microplastics from complex matrices, and the detection conditions, including pH, current density, and processing time were optimised for sensitive detection. Under the optimised calibration conditions, we can detect as low as 0.16-0.62 μg/mL, depending on the type of microplastics and nanoparticle substrates. The spiked lake and river water samples were used to evaluate the recovery. Because microplastics can act as carriers for co-existing organic contaminants, caffeine was selected as a representative co-contaminant to assess microplastic-contaminant interactions, showing that oxidative ageing increased caffeine adsorption onto microplastic surfaces. Experimental results demonstrate the integration of electrocoagulation enrichment and portable SERS detection for near-site microplastic analysis, while also highlighting the influence of co-contaminant interactions on microplastic-associated signal interpretation.