The technique for production of thin-layer chromatographic plates with fixed monolithic layer of sorbent was developed on the basis of investigation of factors affecting sorption capacity, sorption kinetics and mechanical stability of monoliths. The optimal reaction mixture for sol-gel synthesis of monoliths consisted of tetraethoxysilane, buffer solution with pH 7.4, N,N-dimethylformamide, ethanol, polyethyleneglycol with molecular weight 1000 and cetylpyridinium chloride in molar ratio 1.0:4.6:1.4:7.6:0.26:8×10(-3). On the basis of analysis of sorption kinetics of malachite green on the monoliths it was concluded that mechanism of sorption includes chemisorption. The optimized conditions for fixing the monolithic layer on the carrier and its drying allow obtaining undisturbed monolithic layer, which was used for test mixtures separation. The increase of monolithic layer thickness in comparison with ultrathin-layer chromatographic plates allows detecting visually at reasonable concentrations and loaded sample volumes the spots of food and synthetic dyes.

Abstract:In this work the approach for producing thin-layer chromatographic plates with monolithic layer of silica was proposed. The conditions of silica monolith synthesis were optimized by investigation of effects of different catalysts on the properties of obtained materials and addition of drying control chemical additive. The carrier for silica monolithic film was chosen and the method of surface modification was proposed. The properties of obtained monoliths were studied by FTIR and scanning electron microscopy (SEM). Produced thin-layer plates with monolithic layer of silica were successfully used for separation of test mixture of dyes.