Voltammetric Determination of Dinonyl Diphenylamine and Butylated Hydroxytoluene in Mineral and Synthetic Oil

A method is reported for the determination of diphenylamine and butylated hydroxytoluene in mineral and synthetic oil. The procedure used differential pulse voltammetry with a glassy carbon electrode. This method was then used for determining these antioxidants in supporting electrolyte consisting of dilute sulfuric acid and sodium dodecyl sulfonate in ethanol. Anodic peaks were obtained for both analytes. Oxidation peaks at 250 mV were observed from a mixture of butylated hydroxytoluene and dinonyl diphenylamine, allowing their simultaneous determination. This approach was successfully used for the determination of dinonyl diphenylamine and butylated hydroxytoluene in fortified mineral and synthetic oils with good accuracy and precision.