New Stationary Phases for Normal-Phase HPLC Based on Silica Gel Modified with Magnesium, Calcium, Strontium, and Barium Salts

Several new stationary phases for normal-phase high-performance liquid chromatography were synthesized by the modification of silica gel with magnesium, calcium, strontium, and barium salts and subsequent calcination at 700°C. These sorbents exhibit an increase in the retention of organic compounds of the basic character, an increase in the selectivity of separation, and a threefold increase in efficiency in comparison with the initial silica gel. The experimental results were explained on the basis of the interpretation of the IR spectra of pyridine adsorbed on the synthesized and initial silica gels.