Prediction of retention in gas-liquid chromatography using the UNIFAC group contribution method. III. Recent developments in UNIFAC

Previous publications have described the application of the UNIFAC group contribution method to the prediction of retention in chromatographic systems via their thermodynamic properties but concluded that the basic method was of limited, if any, use for this purpose. This paper describes results from some recent developments in UNIFAC including modifications to the equations and newly calculated parameter sets applied to the retention of a range of solvents in squalane, dinonyl phthalate, N-methylpyrollidone, poly (isobutylene) and poly(ethylene oxide) stationary phases. The best results obtained predicted the specific retention volumes to about 10%, although this model could only be applied to a few systems; predictions for a wide range of polar and non-polar systems in the phases could be correlated to approximately 20-25 %. While this level of accuracy is sufficient to allow prediction of elution orders in some systems, none of the modifications to UNIFAC in current use are suitable for widespread application to chromatographic systems.