Development of Traceable Analytical Methods for the Quantification of Microplastics in Complex Food Matrices

Microplastics have emerged as contaminants of increasing concern due to their widespread occurrence in the environment and food chain, raising questions about human exposure and potential health risks. Despite the rapid growth of research in this field, the lack of harmonized analytical methodologies, metrological traceability, and suitable reference materials still limits the production of reliable and comparable data, hindering both risk assessment and regulatory implementation. Addressing these challenges requires more than the development of sensitive analytical techniques; it demands a comprehensive metrological framework capable of ensuring measurement quality throughout the entire analytical process. This PhD thesis contributes to the establishment of a metrological framework for microplastic analysis in complex food matrices through the integration of reference material development, analytical method validation, interlaboratory assessment, and international standardization activities. A polypropylene microplastic reference material was developed and characterized to support method validation and quality assurance, representing a step towards traceable measurements. In parallel, a Raman spectroscopy-based analytical methodology was developed and validated for the identification and quantification of small microplastics in infant milk formula, one of the most analytically challenging food matrices due to its complex composition. Particular attention was devoted to sample preparation, contamination control, and optimization of analytical parameters to improve measurement robustness and reliability. The performance of vibrational spectroscopic techniques was further investigated through an interlaboratory comparison specifically designed to evaluate the influence of particle size on analytical accuracy and reproducibility. The results highlighted the current capabilities and limitations of available methodologies, identifying particle size as one of the major factors affecting measurement performance and emphasizing the need for harmonized analytical criteria. Beyond methodological developments, this work actively contributes to international standardization initiatives by supporting collaborative studies on reference materials, quality assurance strategies, and measurement comparability. These activities strengthen the scientific basis required for the implementation of standardized methods in environmental and food analysis. Overall, this thesis demonstrates that reliable microplastic quantification cannot rely solely on increasingly sensitive analytical instrumentation but requires a comprehensive metrological approach encompassing traceability, validated methodologies, reference materials, and interlaboratory comparability. By integrating these complementary aspects, this work provides practical tools and scientific evidence to support the production of robust microplastic data and their future application in food safety assessment, environmental monitoring, and regulatory decision-making.