Fabrication of naphthol-based phenolic polymer coated-silica for mixed-mode chromatography

Abstract

This paper introduces a novel phenolic resin-coated silica stationary phase grafted from the surface of amino-functionalized porous silica microspheres through copolymerization of 1,5-dihydroxynaphthalene and 1,3,5-trioxane in the dispersed state, followed by low-temperature calcination at 200 °C. The new material was identified by scanning electron microscopy, elemental analysis, thermogravimetric analysis and Fourier-transform infrared spectroscopy. The new column has the capability to separate different types of compounds. When utilizing hydrophilic interaction liquid chromatography, sulfonamide drugs and nucleosides/nucleobases could be separated with good resolution even if there were no buffer salts in the eluent. In reversed-phase liquid chromatography, the column indicated satisfactory separation abilities for positional isomers, alkylbenzenes as well as polycyclic aromatic hydrocarbons (PAHs). The selectivity and retention of the new column for PAHs were higher than those for alkylbenzene, which may be affected by the π–π forces between the PAH analytes and naphthalene ring from the surface of the silica. Depending on the retention mode, the elution order can be reversed using this column. Thus, the stationary phase was intended as a novel mixed-mode column. Meanwhile, the retention and selectivity can be adjusted very flexibly by changing the chromatographic conditions.