Vapor Pressure and Thermodynamics of L-Tryptophan Sublimation

The L-tryptophan sublimation was studied by high-temperature mass spectrometry in the temperature range 395–493 K. The compound evaporates congruently in the form of monomeric molecules. The saturated vapor pressure at 485 K was determined by the Knudsen effusion method. In combination with mass spectrometric data, the pressure equation ln ( p , Pa) = –(19943±304)/ T + (40.568±0.688) is recommended for the temperature range 395–493 K. The enthalpy of 167.5±1.6 kJ/mol for sublimation at 298.15 K was determined on the basis of the second and third laws of thermodynamics.