Retention behaviour of model solutes on mixed silica-magnesia adsorbents by TLC. Comparison with the adsorption properties of Florisil

Summary The retention behaviour of positional isomers (phenols, aniline derivatives, quinoline bases) and polyaromatic hydrocarbons on mixed silica-magnesia layers is examined using various binary eluents (ethyl acetate, dioxane or 2-propanol in n-heptane). The influence of magnesia content in mixed adsorbents and concentration of polar modifier in the eluent on retention were investigated. Results obtained in chosen systems were compared with retention of solutes on Florisil layers using the same eluents by theR_{M Florisil} vsR_{M mix} correlations. Analysis of the structural effects of solutes and the position of points onR_{M Florisil} vsR_{M mix} diagrams enables comparison of chemical character and distribution of active centers on Florisil and mixed adsorbent surfaces.