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

Direct time-resolved phosphorescence detection enables rigorous quantification of singlet oxygen (¹O₂, ¹Δ_g), 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 (τ_Δ ≈ τ_T). 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.