The Use of Antioxidants to Improve Vapor Pressure Measurements on Compounds with Oxidative Instability: Methyl Oleate with tert-Butylhydroquinone

The vapor pressure (p_sat) of methyl oleate was measured with and without the addition of 0.2 mass % of the antioxidant stabilizer tert-butylhydroquinone (TBHQ). The measurements were made by the gas saturation method with a temperature range of 303.15–343.15 K. In the absence of TBHQ, oxidative decomposition severely compromised the measurements, as evidenced by dramatic decreases in the measured p_sat for repeat measurements at 323.15 K. When combined with a room-temperature N₂ flush of the apparatus, the addition of 0.2 mass % TBHQ limited the decomposition to insignificant levels and resulted in repeatable measurements of p_sat. Simultaneous measurements on the control sample n-eicosane (C₂₀H₄₂) yielded values of p_sat that were in excellent agreement with reference correlations.