The Use of Modified Silica Gels in TLC and HPTLC

At its beginning only very few sorbente were used as stationary phases in thin-layer chromatography. Along with cellulose and aluminum oxides, porous silica gels played a dominant role. The selectivity of the chromatographic system was in most cases adapted to suit a given separation problem by varying the composition of the mobile phase. It was frequently necessary to use multicomponent mobile phases for this. These phase systems were based on a relatively polar stationary phase and a mobile phase which, in comparison, was less polar to varying extents. To reverse the polarity of the phase system and hence also to increase the range of selectivity, the polar supports of the thin layers were occasionally…