Ultrastable long-term tracking and quantification of nanoplastics in complex environmental matrices

Micro- and nano-plastics (MNPs) pose a significant environmental threat, with considerable research focused on their impact on aquatic ecosystems. However, long-term tracking and quantification in complex environments remain challenging. To address this, we synthesized core-shell nanoplastics (EU@PS) using Eu chelates as a dual-functional tracer for reliable, long-term quantitative tracking via both mass spectrometry and fluorescence imaging in water, sediment and organisms. EU@PS exhibit high sensitivity, with a detection limit of approximately 0.5 μg/L (2*10 ⁴ particles/mL) in single-particle ICP-MS mode. Critically, the Eu core demonstrated exceptional stability, retaining over 83.1 % of its mass after 28 days of exposure and unaffected by ultraviolet light. In a microcosm experiment, we tracked the partitioning dynamics between water and sediment and bioaccumulation in D. magna. More than 95 % of the particles settled in sediment within 10 days at 1 and 10 mg/L concentrations, with a sedimentation rate constant of 0.20/day. Fluorescence imaging confirmed particle accumulation primarily in the gut of D. magna, reaching a concentration of 4.8 μg/g even at a low exposure concentration of 50 μg/L. This study provides a stable method for tracking the environmental fate of nanoplastics, highlighting the importance of tracer stability in environmental studies.