CS241346B1 - Sorbent preparation method with high density of chemically bonded octadecyl phase - Google Patents

Abstract

The invention relates to a process for preparing sorbents high density chemically bonded octadecyl phase. The essence of the invention resides in that anhydrous silica gel is applied dimetyloktadecyldimetylamínosilánom or octadecyldimethylchlorosilane and anhydrous pyridine at 10 to 50 Pa at 10 to 190 ° C (10 to 170 hours) and the proportion of the reaction mixture components selects such that the pK of the environment is maintained in between 7 and 8.5. The invention is applicable to preparing sorbents that are applied in chemistry and biology.

Description

octadecyl phase

2

The invention relates to a process for the preparation of high density sorbents of chemically bonded octadecyl phase. SUMMARY OF THE INVENTION The anhydrous silica is treated with dimethyloctadecyldimethylaminosilane or octadecyldimethylchlorosilane and anhydrous pyridine at a pressure of 10 to 50 Pa at a temperature of 10 to 190 ^{° C (} 10 to 170 hours) and the components of the reaction mixture are selected so that The invention has utility in the preparation of sorbents that are applied in chemistry and biology.

[0030] The method for the preparation of the process mixture is a concrete and a densification of the specific density of the ocadecyl phase.

A major advance in, ..chrQrnatftgr ^ Carp tissue specific analysis in place, and $ áp'lňí 'ěÉějntcky bound "liquid" mSzdm ^w · Vďáúď this cartridge was greatly decrease the duration of the analysis and to allow the quantitative and qualitative separation of agents with similar properties. Cartridges with chemically bonded phases are sorbents obtained by the reaction of a chemical modifier (e.g., organosilanes with surface hydroxyl groups of a silica gel carrier, porous glass, diatomite, etc.).

In terms of the arrangement of the bound organic groups of the modifier, the general fillers can be divided into two basic groups, the "brush", where the axes of the modifier molecules are oriented perpendicular to the carrier surface and "polymer" type where bound modifier molecules form an undirected, crosslinked monolayer. or more layers - in the form of a film.

Depending on the chemical structure of the modifier and the method of synthesis, various types of linkages are obtained between the organic groups of the modifier and the surface of the support. The stability of the chemically bound phase obtained depends on the type of these bonds. The phases bound by the siloxane bond are characterized by high stability. V. Řehák and E. Šmolková reviewed different types of cartridges used in chromatography [V. Rehak, E. Smolikova: Chromatographia 9, 219 (1976)].

There are many ways to obtain cartridges with a chemically bonded "liquid" phase. Unger et al. recommend silanization using organochlorosilanes as chemical modifiers, with the bound phase structure, density and sorbent coverage efficiency of the organochlorosilane (K. K. Unger, N. Becker, R. Roumeliotis: J. Chromatogr. 125, 115 (1976)).

In the literature, fillings obtained by silanization of sorbent using ethoxyorganosilanes or methoxyorganosilanes [RE Majors: J. Chromatogr. Sci. 18, 489 (1980)]. By the above-mentioned silanization methods, the fillings obtained have an octadecyl group coverage of 2.5 to 3.5 μΐηοΐ. m ^-2 . However, even at this degree of coverage, a significant number of free silanol groups remain on the silica gel surface, which have a large influence on the reproducibility of the retention results and reduce the solvollytic resistance when using aqueous solutions as eluents [NHC Cook, K. Olson: J. Chromatogr. Sci. 18, 1 (1980)].

Therefore, it is also necessary to additionally silane the sorbents using short organic groups, e.g. of methyl, derived from trimethylchlorosilane. Detailed conditions for the above-described syntheses are reported, however, for use as modifiers organochilórsilánov is one undesired reaction products of hydrogen chloride, which has the detrimental ioypf ^ vňyje efficiency and a density of ¹ pojírytia pktadBGylovýml groups. ¹ · '' - ^{α 4}

Silanization with chlorosilanes is used for. this is done in the pyridine environment, which binds, releasing ⁵ % hydrogen chloride. In this case, however, the degree of coverage of the sorbent surface with alkyl groups usually decreases. The use of ethoxysilanes as a silanizing agent is not preferred due to the ease of formation of unwanted polymeric film on the surface of the sorbent under unsecure (absolute anhydrous environment.

These disadvantages substantially eliminate the high sorbent preparation process. The density of the chemically bonded octadecyl phase according to the invention is based on the finding that optimal silanization results are obtained at a pK of 7 to 8.5. 100 ° C to 190 ° C. The necessary pK is provided either directly by the basic silanizing agent or by the addition of the pyridine base to the acidic silanizing agent.

According to the invention therefore, in the fact ^'that the anhydrous silica treated with N, N-dimetylamínooktadecylsilán oktadecyldimetylchlórsilán or anhydrous pyridine, pressure of 10 to 50 Pa, respectively. in the presence of an inactive anhydrous solvent such as e.g. toluene, at a temperature of 100 to 190 ° C for 10 to 170 h, the proportions of the individual components being chosen so that the pK of the medium is in the range of 7 to 8.5.

The role of the pK environment is critical as it ensures the most favorable course of the reaction and leads to high coverage of the sorbent.

An advantage of the proposed method of preparing sorbeptes over the prior art processes is that, with the present method, the sporoborose obtains fillings with a high density of chemically bonded octadecyl phase of 3.6 to 0.1 μΐηοΐ. m ^- ?, good solvolytic and mechanical strength. As a result, no additional is needed. .silanizácia ^

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5.g, silica gel; with a specific surface area of 420 meters ² , g. ^A separate supply of reagents is added to the reactor which allows heating. and prevents reagents from coming into contact with the environment. The sorbent is dried in the reactor at 10 Pa at 200 ° C for 4 hours to remove adsorbed water. The sorbent is then reacted with 7 ml of N, N-dimethylaminooctadecyldimethylsilane (18 micromol.m ^-2 ). This amount is in triple excess to the amount of silanol groups found on the silica gel surface, providing a pK reaction of 8.5.

The reactor is heated to 130 ° C for 170 hours. After cooling and opening the reactor, the sorbent is transferred to a funnel and washed successively: benzene, acetone, methanol and finally 50 ml of diethyl ether to wash off the reaction residues. The eluted sorbent is dried. The sorbent with the chemically bonded octadecyl phase obtained in this way has a coverage density of 6.6 μΐηοΐ. m ^-2 .

Example 2

The procedure was as in Example 1 except that silica gel having a specific surface area of 600 m ^{2 was used} . ^g1 , which is dried at 50 Pa and 200 ° C for 6 hours. 15 ml of dry toluene and 9 ml of dimethylamino-octadecyldimethylsilane are then added to ensure a pK of 8.5. The reactor was heated to 150 degrees C for 120 hours. In this way a sorbent with a chemically bonded octadecyl phase with a coverage density of 6/5 µmol is obtained. m ~ ² .

Example 3 g of silica gel having a specific surface area of 380 meters ² . ~ ¹ g was charged into a glass reactor as Example 1 and dried at a pressure of 10-50 Pa at a temperature of ^200? C for 6 hours. Then 20 ml of 0.5 mol. I ^-1 oktadecylchlórsilánu solution of anhydrous toluene and 5 ml dry pyridine. Pyridine binds the resulting hydrogen chloride and maintains a pK reaction of about 8.5. After loading and adding the reagents, the reactor is closed and heated to 100 ° C for 10 hours. After the reaction, the contents were washed on a funnel and dried as in Example 1. A sorbent with a chemically bonded offadecyl phase with a density of 5.8 micromoles was obtained as described above. m ~ ² .

Example 4

The procedure is as in Example 3, using silica gel having a specific surface area of 340 m ² . g ¹ and a solution of 6 ml of octadecyldimethylchlorosilane in 5 ml of anhydrous pyridine is added giving pK 8. The reaction temperature is maintained at 120 ^and C for 12 hours. In this way, a sorbent having a chemically bonded octadecyl phase with a coverage density of 5.4 µmol is obtained. m ~ ² .

Example 5

The procedure is as in Example 3, except that silica gel with a specific surface area of 240 m ^{2 is used} . g ¹ and the solution was added 5 ml of 15 oktadecyldimetylchlórsilánu miililitroch of anhydrous toluene and 2 'ml of dry pyridine, gives the pK of 7 reaction temperature 120 ° C was maintained for 10 hours. In this way, a sorbent with a chemically bonded octadecyl phase with a coverage density of 3.6 μΐηοΐ is obtained. m ~ ² .

The high density sorbent of the chemically bonded octadecyl phase can be widely used as a packed column, for analytical and preparative chromatographic separations, as well as in thin-layer chromatography and in equipment used in clinical and biochemical diagnostic analyzes and for preconcentration and pre-separation of diluted and multi-component systems.

Claims (2)

SUBJECT 1 A process for the preparation of high density sorbents of a chemically bonded octadecyl phase in which anhydrous silica is treated with a silanizing agent selected from the group consisting of Ν, dial-dialkyl- * octadecylaminosilane or diailkyloctadecylchlorosilane acting alone or in the presence of pyridine characterized in that the reaction is carried out at temperatures of 100 to 190 ° C for 10 to 170 hours and that: The proportion of the components of the reaction is chosen so that the pK of the medium is in the range of 7 to 8.5. 2. A process according to claim 1, wherein the weight ratio of the silanizing agent to the starting anhydrous silica gel is in the range of 0.3 to 1.2 and the volume ratio of pyridine to the silanizing agent is in the range of 0.4 to 1.2.