Modification of HPTLC‐plates by in situ chemical bonding with non‐polar and polar organosilanes

Abstract

AbstractA method has been developed for the preparation of modified silica plates for high performance thin‐layer chromatography (HPTLC). Some typical organosilanes were thus allowed to react in situ with the silica of Merck HPTLC‐plates. This method was found to be highly reproducible, simple and cheap. Non‐polar plates were prepared and compared with commercial plates from Merck, Whatman and Macherey‐Nagel. Modification with cyanodecyltrichlorosilane resulted in plates that showed good coverage, efficiency and low residual silica activity. Silica modified with a multifunctional silane has different properties in different organic solvents. It will appear to be non‐polar in a polar solvent and vice versa. New advantageous separation systems are thus made feasible by the presence of cyano groups on the plate.The utility of modified thin‐layer plates is demonstrated by the separation of some homologues of p‐hydroxybenzoic acid esters and of some polycyclic aromatic hydrocarbons.