Prediction of retention in gas-liquid chromatography using the UNIFAC group contribution method. II. Polymer stationary phases

The UNIFAC group contribution method and its free volume modified version have been used to calculate thermodynamic activity coefficients and hence specific retention volumes for a number of solutes at infinite dilution in a range of polymeric gas-liquid chromatographic stationary phases including Carbowax and several of the OV series of methyl silicones. Specific retention volumes and partition coefficients have been calculated and used to predict relative retentions and the order of elution of the solutes, and these were compared to corresponding experimental values. However, although in some cases the results were predicted to within a few percent of their experimental values, in general the agreement is not good enough to give a reliable predictive method for a range of solvents and so reinforces the conclusions from work on low-molecular-weight stationary phases that the wider application of group contribution methods awaits future developments.