Determination of the vapor pressure of Lippia gracilis Schum essential oil by thermogravimetric analysis

• The Lippia gracilis S. essential oil rich in thymol was studied.
• Vapor pressure for the essential oil was determined by thermogravimetry.
• Thymol is the major component of the oil and was used as the reference compound.
• The vapor pressure was compared the vapor pressure curve for carvacrol.
• Good agreement of the vapor pressure of the carvacrol with literature values.

Thermogravimetric analysis was used to determine the vapor pressure of the Lippia gracilis S. essential oil. The calibration constant value was obtained using thymol as reference compound, due to the fact that compound represents the majority in the essential oil. To check the calibration, the vapor pressure data for carvacrol have been compared with the results reported in the literature and showed a good agreement. The method was used in the determination of the vapor pressure curve for the essential oil. From vapor curves, the Antoine constants for the essential oil were found to be: A = 10.29230, B = 3116.68 and C = 74.23, respectively.