Sublimation and vapour pressure estimation of l-leucine using thermogravimetric analysis

The sublimation kinetics of amino acid l-leucine is studied with the isothermal thermogravimetric (TG) analysis at temperatures between 400.7 and 517.5 K. Sublimation of l-leucine follows zero order kinetics. l-leucine begins to sublime around 423.2 K and sublimation rate increases exponentially with increasing temperature. The vapour pressure of l-leucine is determined based on the mass loss rate showing a good correlation with literature values. Using the Arrhenius equation, the activation energy and pre-exponential factor are determined. The sublimation enthalpy and entropy are obtained using the Clausius–Clapeyron equation.