Retention Characteristics and Sorption Enthalpies of Esters of Natural Hydroxycarboxylic Acids on DB-1 Stationary Phase

Sorption characteristics and retention of esters of glycolic, lactic, malic, and tartaric acids with C₁‒C₈ alcohols of linear structure are studied by gas-liquid chromatography in the temperature range of 90‒260°C on DB-1 nonpolar phase. The values of the retention indices of the compounds studied are obtained. On the basis of experimentally determined retention times, the thermodynamic characteristics of sorption under the conditions of limiting dilution are estimated. The dependences of the change in sorption enthalpies on the length of the linear alkyl substituent and on the value of the logarithmic retention index are found. The possibility of estimating the energy of intermolecular interactions of lactic acid esters in the liquid phase is shown on the basis of the obtained values of sorption enthalpies and vaporization enthalpies.