Standardized Workflows for Time-Resolved Singlet Oxygen Quantification in Aqueous Systems

Direct time-resolved phosphorescence detection enables rigorous quantification of singlet oxygen (1O2, 1Δg), yet determining reliable photophysical parameters in aqueous environments remains challenging due to rapid solvent quenching and the kinetic coupling between 1O2 and photosensitizer (PS) triplet decays, characterized by similar lifetimes (τΔ ≈ τT). Here we establish standardized workflows for the acquisition and analysis of 1O2 kinetics in homogeneous and heterogeneous aqueous systems, implemented through the open-source SOLIS computational framework. SOLIS applies homogeneous and diffusion-coupled kinetic models to determine quantum yields and lifetimes, perform structured artifact and model-consistency checks, and quantify lipid-to-water signal contributions using objective fit-quality criteria. Benchmarking with reference photosensitizers demonstrates that this workflow mitigates inconsistencies arising from fitting window selection and provides reliable, self-consistent photophysical parameters. By transforming subjective fitting into a defined practical routine protocol, this approach enhances reproducibility and supports quantitative evaluation of oxidative processes across diverse fields, from photodynamic therapy and polymer degradation to chemical synthesis and environmental science.