Tris(hydroxymethyl)aminomethane-functionalized silica particles and their application for hydrophilic interaction chromatography

A new method is presented for synthesizing a highly hydrophilic silica-based material for use in hydrophilic interaction chromatography. Porous silica particles used as a starting substrate were modified with 3-bromopropyl trichlorosilane and grafted with glycidyl methacrylate by controlled ("living") atom transfer radical polymerization in order to introduce an oxirane-carrying reactive tentacle layer on the silica surface. The grafted material was thereafter subject to an oxirane ring opening reaction with tris(hydroxymethyl)aminomethane in dimethylformamide to yield a polymer-bound equivalent of the well known and highly hydrophilic "TRIS" buffering substance. Chemical characterization was done by diffuse reflectance FT-IR, X-ray photoelectron spectroscopy, elemental analysis, and H-1 NMR. Porosity and surface area examination was done with Brunauer-Emmett-Teller. Chromatographic application of the material was evaluated by separations of nucleic bases, small organic acids, and common nucleotides under mixed hydrophilic interaction chromatography and weak anion exchange conditions.