SU753458A1 - Method of producing anion exchanger - Google Patents

Description

(54) METHOD OF OBTAINING ANION EXCHANGER

one

The invention relates to methods for producing ion exchange sorbents and can be used in chemistry, biochemistry, molecular biology, in the microbiological and medical industries.

Methods are known for producing ion exchange pellicular sorbents and sorbents with controlled surface porosity 1.

The sorbents obtained in this case have a small capacity and are unsuitable for the separation of complex mixtures of high molecular weight natural compounds.

The closest to the invention described in the technical essence and attainable result is a method for preparing anionoobmenntska, comprising applying the quaternary amine salt (trimetiloktilammoniyhlorida) hlortriftorpolietilena into pellets in chloroform, followed by trituration slurry to obtain fine and homogeneous phase with 10 micron particle diameter of 2.

This method is characterized by the need to use scarce reagents and the complexity of the operation for obtaining fine sorbent particles. In addition, this method does not allow to obtain anion exchangers with a long service life, since in the process of mx operation a liquid amine is gradually washed out from the surface of the sorbent particles. The latter circumstance causes a change in the capacity of the sorbent and the deterioration of other characteristics, which leads to obtaining reproducible results.

10 The aim of the invention is to obtain an anion exchanger with a long service life, increase efficiency and simplify the method.

The goal is achieved by the fact that the hydrophobised inert carrier,

15 For example, silylated silica gel is treated with a solid salt of trimethyl acetylammonium bromide in chloroform in the amount of 19-29% by weight of the carrier for 20-24 s.

20 A distinguishing feature of the process is the treatment of the hydrophobised silica gel with the solid trimethyl acetylammonium bromide salt. Another difference is that silica gel is treated with methyl methyl acetyl ammonium bromide at a concentration of 19-29% by weight of silica gel for 20-24 hours. The process technology is as follows. Silica gel is silylated with trimethylchlorosilane mixed with hexamethyldisilazane for 1-2 h at room temperature. Next, the silica gel is treated with the solid salt of trimethyl acetylammonium bromide, and the ratio of amine to silica gel can be different depending on the requirements for the capacity of the yielded anion exchanger. It is optimal to use trimethyl acetylammonium bromide at a concentration of 19-29% by weight of silica gel, since with a smaller amount of anion-exchange coating, sorbents with low capacity are obtained that are unsuitable for the separation of complex multicomponent mixtures. Thus, an attempt to use these sorbents to separate a mixture containing more than three oligonucleotides did not lead to success. If the weight content of trimethyl acetylammonium bromide in the mixture is greater than 29%, the thickness of the anion-exchange coating layer is too large, as a result of which the diffusion path of the molecules of the analyzed substances and their sorption are significantly increased. This leads to erosion of the sorption zones, an increase in the retention time of substances on the column and lengthening of the separation process itself. The duration of treatment of silica gel with trimethyl acetylammonium bromide is determined by the composition of the reaction mixture and the larger the ratio of amine: silica gel, the greater should be. At 19% amine content in the mixture, the optimal treatment time is 24 hours, at 29% content - 20 hours. A shorter processing time results in incomplete coating of the silica gel particles with an anion-exchange layer, and a longer duration practically does not affect the properties of the anion exchanger obtained. and impractical because of the increase in time spent on the production of the sorbent, Example 1. A suspension of 25 g of silica gel (type “H, 40 μm, Merck, Germany) in 75 ml of toluene is treated with 2.5 g of trimethylchlorosilane and 2.5 g of hexamethyldisilazane and stirring for 2 hours at room temperature. After that, silylated silica gel is filtered, washed with chloroform and methanol and dried for 10 hours at 100 ° C and 1 mm Hg. Art. A solution of 6 g of trimethyl acetylammonium bromide (Hemapol, Czechoslovakia) in 60 ml of chloroform is poured into 25.6 g of silylated silica gel (60 ml of chloroform) and stirred vigorously for 20 hours until the mass thickens. To completely remove chloroform, the sorbent is dried in a vacuum desiccator at 25 ° C. Example 2. A suspension of silica gel in chloroform is treated with trimethylchlorosilane and hexamethyldisilazane according to the procedure described in Example 1. Then a solution of 6 g of trimethyl acetylammonium bromide in 60 ml of chloroform is poured into 14.7 g of silylated silica gel, and further operations are then vigorously mixed according to Example 1. The proposed anion exchanger was used to separate different mixtures of oligonucleotides. The table shows the change in the retention time of the oligonucleotide d (pT-AGT) and the standard deviation in the quantitative determination of this oligonucleotide on columns (2.4 mm X 25 cm) with a known and obtained anion-exchanger in the conditions of elution with a concentration gradient of acetate monomer buffer ( 0.1-0.8 M, pH 5.0). The test results indicate that the chromatographic characteristics of the anion exchanger obtained remain practically unchanged after six months of operation, while the known sorbent is unsuitable under the specified conditions after three months of its use. The conventions adopted in the structural formulas of oligonucleotides are given on page 5. The standard deviation was calculated using the formula ±, where xi is the magnitude of i-ro measurements, x is the arithmetic average of all measurements, is the n-number of measurements. FIG. 1 and 2 are chromatograms for fractionation of mixtures of oligonucleotides. The ordinate indicates the optical density of the eluted solution in units of optical density at a wavelength of 254 nm; abscissa - elution time in minutes. FIG. 1 peak 1-3, etc., correspond to MONO-, DI-, tri-, etc. to adenylic acid oligomers. FIG. 2 peak 1 corresponding oligonucleotide d (pT-C), peak 2 - d (pA-i), peak 3 - d (pT-G), peak 4 - d (CC-Ap), peak 5 - d (pT) 3, peak 6 - d (pT-GG), peak 7 - d (pT-AGT) and peak 8 - d (ATGTT-) "To abbreviate oligonucleotides, the following abbreviations are accepted: d - deoxyribose, p - terminal phosphate group, T - thymidine, C - cytidine, A - adenosine, G. - guanosine. The above chromatograms indicate that the obtained anion exchanger can be used to efficiently separate different oligonucleotides both in the chain length and in the nucleotide composition. The proposed method of producing an anion exchanger is much simpler than the known one, since it eliminates the need for a laborious stage of grinding sorbent particles and obtaining a homogeneous homogeneous fraction.

Claims (2)

Continued table. Thus, the anion exchanger obtained by the proposed method has a long service life (up to six months) without loss of chromatographic properties, since the solid ion exchange layer deposited on a substrate of silylated silica gel is not washed off during operation. The use of trimethyl acetylammonium bromide as an anion exchange coating provides the sorbent with high efficiency and resolution, allowing for the rapid separation of mixtures containing high molecular weight compounds of polyanionic nature. Claim 1. A method for producing an anion exchanger by treating an inert carrier with organic liquid in chloroform and then removing chloroform, characterized in that, in order to simplify the process and increase the service life of the anion exchanger, the process is carried out by treating the hydrophobic silica gel with trimethyl acetylammonium bromide. 2. The method according to claim 1, characterized in that trimethyl acetylammonium bromide is taken in an amount of 19-29% by weight of the carrier and the process is carried out for 20-24 hours. Sources of information taken into account in the examination 1. US patent number 3577266, cl . 117-100. 2.A .. D. Kelmers, D. E. Hertherly, Anal. Biochem .. 44, 486 (1971). Collators for Rapid Chromatographed Selections for Small Amounts of Tracer-Labelled Transfer Ribonucleic Asids. (Ptiz. I