Indirect headspace gas chromatographic method for vapor-liquid phase equilibrium study

This study reports on an indirect headspace gas chromatographic method for the study of vapor-liquid phase equilibrium (VLE). The method uses two sample vials filled with an identical solution of different volumes. The VLE partitioning coefficient of the solute is derived from the ratio of the peak areas of the solute from two independent headspace GC measurements of the two vials at equilibrium. Mathematical precision analysis and experimental verifications indicate that the volume ratio of the solutions in the two testing vials is a key parameter that dictates the accuracy of the method, and che present method can accurately measure a wide range of VLE partitioning coefficients of solutes. The method is rapid and automated. It does not require one to know the solute concentration in the system or to modify the sample matrix. Therefore, it has significant importance in many industrial, environmental and other practical applications. (C) 1998 Elsevier Science B.V.