CS257478B1 - A method for preparing immobilized stationary phase silicone, modified with nitrogen bases for gas chromatography - Google Patents

Abstract

The current method of preparing capillaries with immobilized silicone stationary phases modified with a nitrogen base has the disadvantage that it requires a complex preparation of a nitrogen copolymer of the type of barbituric acid derivatives, as well as a special deactivation of the capillaries. The essence of the solution lies in the fact that the silicone prepolymer and trialkylamine, alkylpyridine or vinylpyridine, in a mutual weight ratio of 100:2.5 to 30, with a catalytic effect of 2.5 to 10 parts by weight of bis/alpha, alpha-dimethylbenzyl/-peroxide or dibenzoylperoxide, based on the silicone prepolymer, are allowed to polymerize after removal of the solvent in the absence of air at a temperature of 130 to 170 °C for 30 to 120 minutes.

Description

The invention relates to a process for the preparation of an immobilized nitrogen-modified stationary phase of silicone type for gas chromatography.

The prior art process for the preparation of capillaries with mobilized silicone stationary phases modified with nitrogen base consists in the joint polymerization of silicone prepolymer and vinyl or vinyl carbonate. allyl barbiturate at elevated temperature and under the catalytic action of organic peroxide (W.M.L. Chow and B, Caddy: J. Chromatogr., 318, 225-268, (1985)).

The disadvantage of the prior art process is that it requires the complex preparation of a nitrogen copolymer of the barbituric acid derivative type as well as the special deactivation of capillaries.

These drawbacks can be overcome by preparing an immobilized nitrogen-base modified silicone-type stationary phase for gas chromatography, polymerization of the prepolymer at elevated temperature under the catalytic action of the organic peroxide according to the invention.

SUMMARY OF THE INVENTION The silicone prepolymer and trialkylamine wherein the alkyl has 1 to 5 carbon atoms and the alkyls are the same or different, the alkyl pyridine having 1 to 3 carbon atoms in the pyridine alkyl and the 1-3 alkyl on the nucleus, wherein the alkyls are the same or porous, or vinylpyridine, in a weight ratio of 100: 2.5 to 30 relative to one another, with catalytic action

2.5 to 10 parts by weight. The bis (alpha, alpha-dimethylbenzyl) peroxide or dibenzoyl peroxide, based on the silicone prepolymer, is allowed to polymerize for 30 to 120 minutes at 130 to 170 ° C in the absence of air at 130-170 ° C. In this way, a non-extractable stationary phase film with an o-chromatographic properties different from the original silicone polymer is formed on the inner wall of the glass capillary.

An advantage of the process for the preparation of the immobilized stationary phase of the silicone type according to the invention is that the phase preparation is simplified compared to the prior art, conventional capillary deactivation can be utilized and the spectrum of silicone prepolymers broadened.

These examples illustrate but do not limit the scope of the invention.

Example 1

A soda-lime soda-lime glass capillary column of type Unihost is packed with a solution containing 100 parts by weight. 9.5 parts by weight of silicone prepolymer (methylphenylvinyl silicone); triethylamine and 2.5 parts by weight of bis / alpha, alpha-dimethylbenzyl] -peroxide in di-chloromethane.

One end of the capillary is hermetically sealed after filling with the solution and the other evaporates the solvent under high vacuum. After evaporation of the solvent and after flushing with nitrogen at both ends, the column is sealed and placed in an oven where it is heated to 150 ° C at a rate of 5 ° C / min.

At 150 ° C the column is left for 60 minutes

Example 2

A Simax borosilicate glass capillary column is packed with a solution containing 100 parts by weight. 10 parts by weight of methyl silicone prepolymer. 4-vinylpyridine and 3 parts by weight. bis (alpha, alpha-dimethylbenzyl) -peroxide in dihalo-methane. After filling the capillary with the solution, proceed as in Example 1, except that the polymerization is carried out at 30 ° C for 30 minutes.

Example 3

The Unihost soda-lime glass capillary column is packed with a solution containing 100 parts by weight. % methylphenylsilicon prepolymer, 2.5 parts by weight 2,6-dimetypyridine, and 2 * 5 parts by weight. bis / alpha, alpha-dimethylbenzyl] -per’oxide in di-chloromethane. After filling the capillary with the solution, proceed as in Example 1.

Example 4

The glass capillary column of Simax borosilicate glass is packed with a solution containing 100 parts by weight. of methylvinyl silicone prepolymer 5 parts by weight. N-methyl-N, N-di-n-propylamine and 10 parts by weight of N-methyl-N-N-propylamine; of dibenzoyl peroxide in dichloromethane. After the capillary was filled with the solution, it was continued as in Example 1, except that the polymerization was carried out at 170 ° C for 90 minutes.

Claims (1)

OBJECT OF THE INVENTION A process for the preparation of an immobilized stationary phase of a silicone type modified with nitrogen bases for gas chromatography by polymerizing a silicone prepolymer of methylphenylvinylsilicone at an elevated temperature under the catalytic activity of an organic peroxide, characterized in that the silicone prepolymer and alkyl are the same or different, C 1 -C 3 alkylpyridine with 1 to 3 core nuclei, wherein the alkyls are the same or different, or vinyl pyridine, in a weight ratio of 100: 2.5 to 30 relative to each other, with a catalytic effect of 2, 5 to 10 parts by weight. The bis (alpha, alpha-dimethylbenzyl) -peroxide or dibenzoyl peroxide, based on the silicone prepolymer, is allowed to polymerize in an air-free atmosphere at 130-170 ° C for 30-120 minutes after removal of the solvent.