GAS-LIQUID PARTITION CHROMATOGRAPH FOR THE ACCURATE DETERMINATION OF INFINITE DILUTION ACTIVITY-COEFFICIENTS

A gas-liquid partition chromatograph (GLPC) has been constructed for the accurate determination of K values and activity coefficients at infinite dilution. There are several salient features of this apparatus which are improvements over previously reported models. Vaporization of the stationary phase in the GLPC column is suppressed by operating at elevated pressures, minimizing pressure drop across the GLPC column, and presaturating the carrier gas so that data can be taken over a wide temperature range. Retention time measurement is improved by the use of a custom designed electronic timer and a flow pattern in which solutes pass through the thermal conductivity detector before and after the GLPC column. A very stable and accurate means of pressure and flow control is used. The pressure measurement is more accurate than reported in other GLPC papers. Error analysis shows the propagated error due to inaccuracies in measured quantities is 0.4% for K values. Uncertainty may be larger for activity coefficients because of the need for estimating fugacities. Data are reported for a number of paraffin and aromatic hydrocarbons, including poly nuclear aromatics, as solutes in n-hexadecane, 1-methylnaphthalene, and phenanthrene at temperatures from 60 to 180 °C. © 1979, American Chemical Society. All rights reserved.