UV-Triggered Chemiluminescence as a Bulk Surrogate Indicator for Microplastic Contamination in Aquatic Matrices

High-throughput assessment of microplastic (MP) contamination in complex waters remains challenging because particle-resolved methods are low-throughput and inherently limited by size-dependent detection, particularly for nanoplastics. Here we report a UV-triggered chemiluminescence (CL) bulk-screening assay in which microplastic-derived dissolved organic matter (MP-DOM) generated during controlled UV weathering is transduced into a quantitative luminol-H₂O₂ flow-injection CL (FIA-CL) readout. Each measurement requires only a 30 min pretreatment, 1 mL of sample, and a few-minute analysis. Polyethylene (PE) and polystyrene (PS) produced reproducible, time-resolved CL transients, and peak intensity responded linearly to MP loading over 0.1-0.5 g L^-1 (R² > 0.92) with polymer-dependent sensitivity. The assay performed optimally under near-neutral pH and 30 min irradiation conditions, while iron oxide (Fe₂O₃) was identified as a major interferent that markedly suppressed emission. Optical characterization (UV absorbance and EEM-PARAFAC) showed that CL intensity correlated with dissolved organic carbon and humic-like components (R² = 0.43-0.60), suggesting that both the amount and composition of UV-generated MP-DOM contribute to signal generation. Application to urban streamwater and wastewater effluent demonstrated the assay's utility in realistic matrices. Overall, the UV-assisted FIA-CL approach provides a rapid, mechanistically supported complementary bulk-screening surrogate for comparative assessment of MP contamination across aquatic samples.