This work examines the use of two different sets of standards to evaluate vaporization enthalpies and liquid vapor pressures of a series of polycyclic hydrocarbons that include adamantane, diamantane, and a and beta-cedrene by correlation gas chromatography. Several n-alkanes and a series of cyclic and polycyclic hydrocarbons were selected as standards to independently evaluate the appropriateness of using nalkanes to evaluate these properties in two branched polycyclic sesquiterpenes. Vapor pressures of two of the polycyclic hydrocarbons examined, 1,3-dimethyladamantane and 1,4-di-t-butylbenzene, are known and the results obtained using n-alkanes as standards were used for comparisons. Standards for evaluation of adamantane and diamantane included these two compounds along with alpha-pinene, and camphene; a series of n-alkanes were also used in separate experiments for evaluation of the adamantanoids. The n-alkane standards included decane and dodecane through to pentadecane. Vapor pressures for adamantane and diamantane evaluated in this work were combined with literature values for 1,3-dimethyladamantane and 1,4-di-t-butylbenzene at elevated temperatures to also evaluate liquid vapor pressures and vaporization enthalpies for alpha- and beta-cedrene. The results were compared to those evaluated independently using n-alkanes. The results of the experiments are discussed. (C) 2018 Elsevier Ltd.