Temperature dependence of solvation heat capacities by gas chromatography

The temperature dependence of molar solvation heat capacity has been determined in the temperature range of 30-160 °C for C6-C10n-alkanes and McReynolds test compounds on 100% poly(dimethylsiloxane) (PDMS) FSOT columns using the equations involving the temperature dependence of solvation enthalpy and entropy. The evaluation method is based on a rigorous statistical evaluation of the parameter estimations. On PDMS, column solvation heat capacity versus temperature curves are S-shaped for n-alkanes and for 1-butanol, while the temperature dependence of the other test compounds is more complicated. The results show near monotonous decrease of solvation heat capacity in the whole temperature range. Harmonic oscillator-rigid rotor assumption rationalizes the curves in a simplified way.