Abstract Chemically modified silica gels were prepared and examined by use of solid-state 13C and 29Si cross-polarization and magic angle spinning nuclear magnetic resonance spectroscopy. By this method, one can not only distinguish between various structural elements in the surface region, but also differentiate according to their mode of preparation. The results of the original manufacturing procedures for reversed-phase high-performance liquid chromatography materials and their subsequent treatment with trimethylsilylating reagents can be investigated. It is also possible to decide whether the solvents ( e.g., methanol) used in the preparation remain adsorbed at the surface or are completely removed by heat treatment. Further developments of this method of investigation may reveal the molecular mechanism of chromatographic separations.