Selectivity equivalence of two poly(methylphenylsiloxane) open-tubular columns prepared with different deactivation techniques for gas chromatography

The solvation parameter model is used to characterize the retention properties of a poly(methylphenylsiloxane) column Rxi-50 over the temperature range 60-240 °C. The smooth variation of the system constants with temperature affords a general picture of how the relative importance of the different intermolecular interactions change with temperature. The system constants and retention factors for varied compounds are compared with those for Rtx-50 prepared with a similar stationary phase but using a different surface deactivation technique. The two columns are shown to be nearly selectivity equivalent. The Rtx-50 column is slightly more cohesive, dipolar/polarizable and hydrogen-bond basic than Rxi-50, while Rxi-50 is slightly more electron lone pair attractive and hydrogen-bond acidic. Only the difference in hydrogen-bond acidity can be identified with some certainty as related to the difference in deactivation processes. For compounds with a separation greater than 0.2 retention factor units on Rtx-50, it should be relatively straightforward to achieve an acceptable separation for the same compounds on Rxi-50.