The vaporization enthalpies of a mixture of n-alkanes, aliphatic esters, and dialkyl phthalates are examined both by correlation gas chromatography and another commonly used gas chromatographic retention time technique according to the protocol described by Hamilton. The resulting vaporization enthalpies and vapor pressures at T/K = 298.15 are compared with respect to the functional groups present. Additionally, two compounds, docosane and ethyl octadecanoate, exhibited retention time coincidence over a T/K = 30 temperature range. These compounds have been examined by correlation gas chromatography to determine how this coincidence affects the therrnochemical properties evaluated.