Developing new analytical methodologies for the identification and quantification of micro- and nano- plastics

Plastic pollution has emerged as a critical environmental challenge, with nano- plastics (less than 1 µm) raising growing concern due to their ubiquity, persistence, and potential biological impact. This thesis presents the development and validation of an analytical workflow for the detection, characterisation, and treatment of nano-plastics in freshwater environments. It combines a comparative study of chemical pretreatment methods with advanced particle analysis techniques, offering methodological insights and practical tools for environmental monitoring. Key objectives included assessing the efficacy of oxidative, alkaline, and enzymatic digestion methods in preserving particle integrity while removing organic matter, and evaluating the performance of dynamic light scattering (DLS) and resistive pulse sensing (RPS) in analysing nano-plastic size and concentration. RPS was found to offer superior resolution and sensitivity for sub-micron particle analysis compared to DLS. The study also introduces a novel electrochemical microfluidic treatment device that facilitates selective particle separation in environmental samples, showing potential to reduce background interference and improve sample purity. Field validation was conducted through a year-long study of three freshwater systems in Leicester, UK (King Lear Lake, the River Soar, and the Grand Union Canal). Seasonal trends in nano-particle concentrations were observed, with higher particle loads correlating with rainfall and runoff events. Combined pretreatment strategies, including electrochemical techniques, achieved up to 96% particle removal. While definitive identification of plastic polymers was limited by hardware constraints, spectroscopic and SEM-EDX analysis indicated the presence of synthetic, carbon-rich particulates. This research contributes a robust, field-applicable methodology for nano-plastic analysis, demonstrates the utility of RPS in complex environmental matrices, and pioneers electrochemical purification as a preparatory step. The work provides foundational insights for future monitoring, regulation, and mitigation of nano-plastic pollution in aquatic systems.