Evaluating the greenness of MP-AES spectroscopy through AGREE metrics

The principles of green chemistry have progressively expanded into green analytical chemistry (GAC) and green sample preparation (GSP), fostering the development of quantitative tools such as AGREE and AGREEprep to assess the environmental sustainability of analytical workflows. Although these tools are increasingly adopted, their application is often limited to numerical scoring, with scarce discussion of the underlying assumptions and decision-making processes. This study critically evaluates the applicability and effectiveness of AGREE and AGREEprep in the context of Microwave-induced Plasma Atomic Emission Spectroscopy (MP-AES) analyses, using a real analytical workflow adopted within the Italian PRIN2022 project SECURE-COATS focused on developing functionalized and sustainable coatings for the conservation of stone materials in cultural heritage. The case study involves the determination of Ag, Zn, Ca and P in aqueous solutions obtained from immersion tests in bacterial growth media and from artificial ageing tests, aimed at assessing, respectively, the release of potentially antibacterial metals and the durability of the new coatings. A systematic and transparent data collection was performed to populate both AGREE tools, and the rationale behind each input parameter is explicitly discussed. This approach allows a critical assessment of how methodological choices, instrumental features and sample preparation steps influence the final greenness scores. This work demonstrates their value as decision-support instruments for improving analytical processes also in the field of chemistry for cultural heritage, by reducing both environmental impact and operational costs. The provided data and proposed methodology could serve as a useful reference framework for future green assessments.