Voltammetric method for determining the trace moisture content of organic solvents based on hydrogen-bonding interactions with quinones

Voltammetry experiments were performed on the natural quinone, vitamin K₁ (VK₁), in a range of organic solvents of varying dielectric constant that are commonly used for electrochemicalmeasurements [dimethyl sulfoxide (DMSO), N, N-dimethylformamide (DMF), acetonitrile (MeCN), propionitrile (EtCN), butyronitrile (PrCN), 1,2-dichloroethane (DCE), dichloromethane (DCM), and 1,1,2,2tetrachloroethane (TCE)]. The water content of the solvents was accurately measured using Karl Fischer (KF) coulometric titrations, and the voltammetric data were used to estimate the degree of hydrogen-bonding interactions between the reduced forms of VK₁ and variable levels of water, thereby allowing a ranking of watersubstrate interactions in the different solvents. The voltammetric data were analyzed based on interactions that occur between reduced forms of VK₁ and the water, the solvent, and the supporting electrolyte. Calibration data were obtained that are independent of me nature of the reference electrode and allow the water content of the solvents to be calculated by performing a single voltammetric scan in the presence of VK₁ and 0.2 M supporting electrolyte (Bu₄NPF₆).