Coated capillary chromatographic column
AssigneeThe Dow Chemical Company
InventorsTerry J. Nestrick, Thomas L. Peters, Lester L. Lamparski
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Abstract
In the production of a wall coated open tubular capillary chromatographic column, improved deactivation of the inner surface of a glass or fused silica capillary tube prior to coating with stationary phase is obtained by a multi-step process whereby siloxane polymer molecules are chemically bonded to the capillary inner surface. The process comprises multiple cycles of successive reactions with silicon tetrachloride and a diorganodichlorosilane vapor with intermediate hydrolyses and a final capping reaction with a triorganochlorosilane. The deactivated surface is adapted to coating with an apolar liquid stationary phase.
Claims16
In the process of preparing a chromatographic column using a glass capillary tube, the inner surface of which is etched and acid-activated, or fused silica capillary tube, the inner surface of which is acid-activated, the improved method of deactivating, the inner surface of the capillary which comprises:
- (a) contacting the etched and/or acid-activated surface with SiCl.sub.4 vapor thereby causing substantial chlorosilylation of said surface,
- (b) contacting the chlorosilylated surface with water vapor until essentially all of the chlorosilyl groups have been hydrolyzed to hydroxysilyl groups,
- (c) contacting the hydrolyzed surface with excess of a diorganodichlorosilane vapor of the formula RR'SiCl.sub.2 where RR' each represent a methyl, ethyl, vinyl, or allyl radical, or a mono-chlorinated derivative thereof, to react at least the major portion of the hydroxysilyl groups to form corresponding diorganochlorosilyl groups,
- (d) contacting the reacted surface from step (c) with water vapor until essentially all of the diorganochlorosilyl groups have been hydrolyzed to diorganohydroxysilyl groups,
- (e) contacting the hydrolyzed surface of step (d) with SiCl.sub.4 vapor to react substantially all of said diorganohydroxysilyl groups to form diorganosilyloxychlorosilyl groups,
- (f) repeating steps b-d not less than once, and
- (g) contacting the final hydrolyzed surface from step (f) with a triorganochlorosilane vapor of the formula RR'R"SiCl where RR'R" each represent a methyl, ethyl, vinyl or allyl radical, or a mono-chlorinated derivative thereof, to convert substantially all diorganohydroxysilyl groups to corresponding triorganosilyloxydiorganosilyl groups.
In the process of preparing a chromatographic column of a glass capillary tube, the inner surface of which is etched and acid-activated or fused silica capillary tube, the inner surface of which is acid-activated, the improved method of deactivating the inner surface of the capillary which comprises:
- (a) contacting the etched and/or acid-activated surface with SiCl.sub.4 vapor at about 0.degree.-300.degree. C., thereby causing substantial chlorosilylation of said surface,
- (b) contacting the chlorosilylated surface with water vapor at about 0.degree.-300.degree. C. until essentially all of the chlorosilyl groups have been hydrolyzed to hydroxysilyl groups,
- (c) contacting the hydrolyzed surface with excess dimethyldichlorosilane vapor at about 0.degree.-300.degree. C. for a time sufficient to react at least the major portion of the hydroxysilyl groups to form corresponding dimethylchlorosilyl groups,
- (d) contacting the reacted surface from step (c) with water vapor at about 0.degree.-300.degree. C. until essentially all of the dimethylchlorosilyl groups have been hydrolyzed to dimethylhydroxysilyl groups,
- (e) contacting the hydrolyzed surface from step (d) with SiCl.sub.4 vapor at about 0.degree.-300.degree. C. for a time sufficient to react substantially all of said dimethylhydroxysilyl groups to form dimethylsilyloxychlorisilyl groups,
- (f) repeating steps b-d not less than once, and
- (g) contacting the final hydrolyzed surface from step (f) with trimethylchlorosilane vapor at about 0.degree.-300.degree. C. for a time sufficient to convert substantially all dimethylhydroxysilyl groups to corresponding trimethylsilyloxydimethylsilyl groups.
Dependencies are inferred from the claim text.