Here you find an introduction to the properties of silica and reversed phase surfaces.
In the earliest forms of chromatography the stationary phases were usually polar surfaces ( e.g. silica, alumina ) and the mobile phases were non-polar ( e.g. hexane ). In reversed phase chromatography the polar properties of the two phases are reversed, i.e. a polar mobile phase and a non-polar stationary phase. Hence the name reversed phase chromatography. The traditional form with polar stationary phases are nowadays called straight phase chromatography. It is estimated that about 80% of all analytical chromatographic separations are made in reversed pahse mode. The straight phase mode is not very common today.
Many different types of non-polar stationary phase are available today. Historically, microparticulate silica to which alkyl chains were chemically bonded were the first type. It is still the most common type of reversed material. It offers a broad range of operating conditions to separate mixtures of molecules of different polarity.
In the chemistry section you find a brief discussion of how reversed phase surfaces are synthesised.
In the physical properties section you find a summary of some important properties of reversed phase surfaces.