Interpretation of the mechanisms of chromatographic separation on CN-silica. Part II. TLC of some phenols

Abstract

The chromatographic behavior of some phenolic compounds has been studied with the objective of understanding the role of cyano groups in the processes of chromatographic separation on thin layers of CN-silica gel. For this purpose separations were performed on thin layers of CN-silica gel, unmodified silica gel, and polyacrylonitrile adsorbent (PANS) using fourteen mobile phases, nine of which resulted in normal-phase systems. On the basis of the results obtained the effect of compound structure (i.e. properties of ortho substituents of the compounds separated) on their retention is discussed. The dependence of the order of retention of the phenols on the properties of the adsorbent was also considered. Plots of retention data (R-M against R-M) determined by use of different chromatographic systems were used to characterize the systems used. The results enabled hypotheses to be formulated about possible mechanisms involved in the separations of the phenols on these adsorbents.