Thiol Quantification Using Colorimetric Thiol–Disulfide Exchange in Nonaqueous Solvents

[Image: see text] A careful analysis of two (thiol–disulfide exchange) thiol quantification chromophores’ behavior (Ellman’s reagent and Aldrithiol-4) in nonaqueous solvents is presented. A wide range of kinetic profiles and response factors were measured to exhibit a large variance for nonaqueous systems. We report several robust benchtop and room-temperature methods using different organic solvents compared to aqueous conditions. Validation of analytical analyses in nonaqueous systems and quantification of the cysteine content of ovalbumin are also presented. This work serves as a treatise on the utilization of thiol–disulfide exchange chromophores under nonaqueous conditions for the quantification of thiols.