Sol-gel polymeric stationary phases for high-performance liquid chromatography and solid phase extraction: their method of making
A sol-gel sorbent or chromatography stationary phase is a particulate metal oxide gel containing polymeric segments uniformly distributed throughout the metal oxide gel. The metal oxide gel is an oxide from silicone or other metal oxide that can have one of the valence bonds attached to an organic group and the remainder occupied by oxygens that can be provided as an oxide or an alkoxide or aryl oxide of the polymeric segments. The particles are used for an SPE sorbent or as a packing for a reversed phase high-performance liquid chromatography (RP-HPLC), a normal phase high-performance liquid chromatography (NP-HPLC) column or a hydrophilic interaction liquid chromatography (HILIC) column.
1. A method of preparing a sol-gel sorbent or chromatography stationary phase, comprising:
providing a mixture of metal oxide precursors, water and, optionally, a solvent;
providing a polymer comprising at least one hydroxyl group and, optionally, the solvent or a second solvent;
providing an acid catalyst;
mixing the metal oxide precursors, the water, the polymer, the acid catalyst, and, optionally, the solvent and optionally, the second solvent to form a hydrolysis mixture;
providing a basic catalyst and optionally the solvent, the second solvent, or a third solvent;
adding the basic catalyst and optionally the solvent, the second solvent, or a third solvent to the hydrolysis mixture to form a gelation mixture;
optionally, warming the gelation mixture;
holding the gelation mixture until a gel forms; and
crushing or grinding the gel to form particles of a metal oxide gel containing polymeric segments uniformly distributed throughout the metal oxide gel, wherein the particles are a sol-gel sorbent or chromatography stationary phase.
2. The method according to claim 1 , wherein the metal oxide precursor comprises metal sites in the gel have the structure R x MX (y-x) where M is titanium, aluminum, zirconium, germanium, barium, gallium, indium, thallium, vanadium, cobalt, nickel, chromium, copper, iron, zinc, boron or any mixture thereof, x is 0 or 1, y is the valence of the metal, X is hydrogen, C 1 to C 4 alkoxy, hydroxy, halide, dialkylamino, or any combination thereof, and R is C 1 to C 6 alkyl or any C 6 to C 14 aryl or polyaryl group where the alkyl or aryl group optionally is functionalized with C 1 to C 20 alkyl, C 6 to C 14 aryl, halo, hydroxy, alkoxy, aryloxy, or any other group incapable of neutralizing an acidic or basic catalysts useful for forming the metal oxide gel.
3. The method according to claim 2 , wherein M is Si, X is C 1 to C 2 alkoxy, x is 0 or 1, and, R is methyl.
4. The method according to claim 1 , wherein the polymer comprises a silicone, a polyether, an acrylate, a methacrylate, polyesters, or a polyamide.
5. The method according to claim 4 , wherein the polymer is polydimethylsiloxane, polytetrahydrofuran, or polyethylene glycol.
6. The method according to claim 4 , wherein the polymer comprises a homopolymer, random copolymer, block copolymer, graft copolymer, or a dendrimer.
7. The method according to claim 1 ,
wherein the metal oxide precursor comprises metal sites in the gel have the structure R x MX (y-x) where M is titanium, aluminum, zirconium, germanium, barium, gallium, indium, thallium, vanadium, cobalt, nickel, chromium, copper, iron, zinc, boron or any mixture thereof, x is 0 or 1, y is the valence of the metal, X is hydrogen, C 1 to C 4 alkoxy, hydroxy, halide, dialkylamino, or any combination thereof, and R is C 1 to C 6 alkyl or any C 6 to C 14 aryl or polyaryl group where the alkyl or aryl group optionally is functionalized with C 1 to C 20 alkyl, C 6 to C 14 aryl, halo, hydroxy, alkoxy, aryloxy, or any other group incapable of neutralizing an acidic or basic catalysts useful for forming the metal oxide gel;
wherein the polymer comprises a homopolymer, random copolymer, block copolymer, graft copolymer, or a dendrimer; and
wherein the polymer comprises a silicone, a polyether, an acrylate, a methacrylate, polyesters, or a polyamide.