Unraveling microplastics release in bottled water under in-vehicle conditions using carbon quantum dots

Exposure of plastic cups/bottles to high temperature and sunlight results in the release of microplastics (MPs), raising significant health and environmental concerns. This study established a novel, quantitative detection framework of MPs from bottled water with polyethylene terephthalate (PET) packaging stored under in-vehicle thermal and sunlight stress. Leveraging ethylene glycol-derived carbon quantum dots (EG-CQDs) as fluorescent probes, the study addressed limitations in traditional MPs detection by achieving high sensitivity (LOD: 0.15 ppm), operational simplicity, and compatibility with ionic matrices. Our findings confirmed that EG-CQDs exhibit size-independent stability and sensitivity for PET detection, with fluorescence intensity correlating linearly (R² >0.9) across two concentration ranges: 0–0.5 ppm and 0.5–50 ppm. By combining controlled vehicle exposure simulations with optical, chemical, and morphological analyses, this study revealed that prolonged sunlight and heat accelerated PET degradation, producing up to 10.03 ppm MPs within 28 days. Findings provide mechanistic insight into CQDs–PET interactions, validate the dual role of photothermal degradation, and contextualize environmental risks of bottled water misuse in transport scenarios.