A Reconsideration of the Rohrschneider Approach for Characterizing Gas Chromatographic Liquid Phases. II. Use of Four Functional Probes

Abstract

In Part I of this series (preceding paper) three predominant types of solute-solvent interactions in gas-liquid chromatography (GLC) were identified: dispersion, dipole orientation, and hydrogen bonding. The implication of this result is that only four “functional probes” (including two for hydrogen bonding) should be sufficient to characterize GLC liquid phases. To demonstrate this point, a four-term form of the Rohrschneider equation has been developed which can predict ΔI values with the same accuracy as Rohrschneider's five-term equation (6 index units). The functional probes used and their associated specific interactions are: benzene (dispersion), nitroethane (dipole orientation), n-propanol or chloroform (proton donor) and dioxane (proton acceptor). The approach has been tested using two different sets of data. In agreement with previous work, the most important probe was found to be benzene, since dispersion forces are the predominant type of interaction in typical GLC systems.