FR2519762A1 - SUPPORT FOR THE ANALYSIS OF HYDROPHILIC SUBSTANCES WITH LOW MOLECULAR WEIGHT - Google Patents

Abstract

THE SUBJECT OF THE PRESENT INVENTION IS A POROUS SUPPORT FOR THE ANALYSIS OF HYDROPHILIC SUBSTANCES OF LOW MOLECULAR MASS. IT IS CHARACTERIZED IN THAT IT IS CONSTITUTED OF A CROSS-LINKED COPOLYMER CONTAINING METHYLOL GROUPS, THIS COPOLYMER BEING OBTAINED FROM MONOMERS OF THE STYRENE SERIES AND OF A CROSS-LINING AGENT CO-POLYMERISABLE WITH THE MONOMER, IN THAT ITS SURFACE IS EXTERNAL HYDROPHILIC AND IN THAT THE INTERNAL SURFACE OF PORES IS HYDROPHOBIC. IT RELATES TO A SUPPORT FOR THE ANALYSIS OF HYDROPHILIC SUBSTANCES.

Description

SUPPORT FOR THE ANALYSIS OF HYDROPHILIC SUBSTANCES

LOW MOLECULAR MASS.

  The present invention relates to a porous support for the analysis of hydrophilic substances of low molecular weight as well as to its process of preparation. More particularly, the invention relates to a porous support, for the analysis of hydrophilic substances of low molecular weight consisting of a cross-linked copolymer having methylol groups prepared from a monomer of the styrene series and a crosslinking agent

  copolymerizable with the monomer The outer surface of the support is hydrophilic

  phile due to the presence of a water-soluble polymer attached to it and the inner surface of the pores of the support is hydrophobic or less hydrophilic

than the outer surface of the support.

  Recently, a medium capable of specifically interacting with

  with a substance in living organisms, for example, in high-speed liquid-liquid chromatography often used to analyze substances found in living organisms, in particular, in urine, serum or the like. a carrier capable of being dispersed in serum, urine or the like and interacting with a particular substance present in those media may be applied to an affinity separation of the substances

  and / or antigen-antibody reactions.

  It is known that it is possible to prepare a porous crosslinked polymer of styrene by water suspension polymerization, styrene and a crosslinking agent copolymerizable with styrene, in the presence of a

"regulator" of pore.

  2 'Thus, for example, it is possible, among other things, to find a

  detailed description of a styrene / divinylbenzene copolymer in the

  reviewed "J Polymer Sci" Part 2-A, 835 (1964) Although small grains can be obtained in this process using a water-soluble polymer as the main suspending agent, the water-soluble polymer

  adheres to the surface of small grains and it is difficult to eliminate total-

  the polymer, even by repeated washing

  grains can not be used for gel chromatography

  organic solvent, because the pressure increases because of the visco-

  of the fixed polymer and thus some undesirable reactions occur.

  feels. On the other hand, relatively pure crosslinked styrene polymers can be obtained if, as a suspending agent, a phosphate which is hardly soluble in water such as calcium and magnesium phosphates is used, since it is possible to eliminate easily phosphate by

  washing, small grains obtained, using an acid or the like.

  However, the resulting polymer can not be easily dispersed in water, buffers, serum, urine, etc. because of their hydrophobic surface. The subject of the present invention is a support intended for analysis

  hydrophilic substances of low molecular weight.

  The present invention further relates to a support whose outer surface is highly hydrophilic and whose inner surface

  pores is less hydrophilic than its outer surface.

  The invention also relates to the preparation of these supports.

  The porous support of the present invention consists of a copro-

  crosslinked monomer having methylol groups The copolymer is obtained from a monomer of the styrene series and a crosslinking agent

  copolymerizable with this monomer The outer surface of the support is hydrophilic

  phile thanks to the water-soluble polymer fixed on it The inner surface of the pores of the support is hydrophobic or less hydrophilic than the surface

external support.

  The process of the invention is characterized in that a monomer mixture of the styrene series and a crosslinking agent, copolymerizable with the monomer, are subjected to a suspension polymerization in water in the presence of a regulator. of pore and a water-soluble polymer, the crosslinked copolymer obtained is dried and fixed methylol groups

on the copolymer.

  Other objects and advantages of the invention will appear on reading

of the following description.

  The porous crosslinked copolymer is obtained by polymerization in addition to

  a monomer of the styrene series and a crosslinking agent copolymerizable with the monomer, in a solution of water-soluble polymer, in the presence of a pore regulator By monomer of the styrene series, is understood here to mean styrene , α-methylstyrene, chloromethylstyrene, as well as their combinations as a crosslinking agent copolymerizable with

  monomer, it is possible to use di- or trivinylbenzene, trallyl isocyanurate,

  polyhydroxy alcohol tetracrylate, polyhydroxy alcohol diacrylate or

  Among these agents, diallyl phthalate is particularly preferred.

  to use divinylbenzene because, in this case, it is easy to introduce

  The proportion of crosslinking agent is preferably between 30 and 70% of the sum of the weight of monomer and crosslinking agent. In the present invention, the copolymer

  preferred is the styrene / divinylbenzene copolymer.

  The monomer and the agent are subjected to radical polymerization.

  in the presence of a water-soluble polymer with a high concentration of

  of the present invention, such as polyethylene oxide, polyhydric alcohol,

  polyvinyl acetates, acetates, at various saponification levels,

  polyvinyl pyrrolidone, methyl cellulose, or the like.

  of water-soluble polymer is preferably from 5 to 60% and more particularly

  10 to 40% of the weight of the monomer / crosslinking agent mixture in order to impart good hydrophilicity to the resulting copolymer with less than 5%

  in weight of water-soluble polymer, a sufficient hydrophilicity is not obtained.

  while with more than 60% by weight, small perfectly spherical grains are not obtained and there are some problems in introducing the methylol groups into the resulting small grains because the viscosity of the system is too great. small amount of a phosphate suspending agent such as hydroxyapatite or the like or a

  anionic surfactant, to the aqueous solution of water-soluble polymer.

  The diameter of the copolymer according to the invention can be adjusted by varying the nature and proportions of the water-soluble polymer, the relative proportions of monomer and water, the stirring speed, the amount of surfactant and the like. preferred support of the invention is in the form of spherical grains with a diameter of the order of 1 to 30 p. The pore regulator is used to adjust the pore size of the support; It can be an inert organic solvent insoluble in the monomer. As examples of pore regulators, there can be mentioned 4-

  aromatic hydrocarbons such as benzene, toluene, xylene, hydro-

  chlorinated carbides such as trichlorethylene, chloroform, carbon tetrachloride, aliphatic hydrocarbons such as n-hexane, n-heptane,

  n-octane, n-dodecane and the like as well as combinations thereof.

  In the present invention, the size of the

  pores playing on the nature and / or proportions of pore regulator.

  In general, 20 to 300 parts by weight of regulator are preferably used.

  of pore per 100 parts by weight of monomer / crosslinking agent mixture.

  The dimensions of the pores of the carriers of the invention can be varied.

  according to usage To analyze hydrophilic substances of low molecular weight without absorption of molecular weight proteins

  the molecular weight of exclusion of the supports of the present invention

  must be less than 30 000, that is, the molecular weight of serum proteins. On the other hand, to absorb proteins of molecular weight equal to or greater than 30 000 when hydrophilic substances are analyzed. low molecular weight, it is better

that it be at least 30,000.

  The polymerization initiator may be any conventional initiator employed in the radical suspension polymerization of vinyl monomers, such as, for example, an organic peroxide such as peroxide.

  of benzoyl or butyl perbenzoate, an azo derivative such as azobis

  isobutyronitrile, and the like Peroxide is preferably used

  The water-soluble benzoyl carelipolymer can then be grafted easily.

  If the crosslinked porous copolymer on whose surface the water-soluble polymer is attached or grafted is used as a carrier, the hydrophilic substance has difficulty diffusing into the pores because the hydrophilicity is not sufficiently great, although It is also possible to disperse the copolymer in water. In addition, the copolymer is extremely viscous because of the presence of the water-soluble polymer on its surface and the pressure increases in elution because of the low flow rate of the polymer. eluent and the poor reproducibility of elution, when

is packed in the column.

  For this reason, in the present invention,

  methylol groups in the copolymer to overcome these disadvantages.

  Methods for introducing methylol groups are well known;

  it is possible, for example, to chloromethylate the copolymer and then hydrolyze.

  For example, chloromethylation methods which

  use formaldehyde, or one of its derivatives and the acid

  hydrochloric acid in the presence of ZnCl 2 as a catalyst; use chlorine

  In the chloromethylation reaction, the water-soluble polymer at the surface of the copolymer may also react and the copolymer may stain more than in the absence of methylmethyl ether in the presence of AlCl 3 or SnCl 4 as a catalyst or the like. water-soluble polymer, which causes the appearance of a brown color on the surface of the support The water-soluble polymer which has reacted chemically is partially removed from the

  surface, which makes it possible to obtain a medium of low viscosity.

  If, for example, chloromethyl methyl ether is used, it is employed in a proportion of from 2 to 20 parts by weight per part by weight of crosslinked copolymer and, preferably, from 3 to 10 parts by weight, in order to allow homogeneous agitation and take into account the losses of

  chloromethyl methyl ether by evaporation during the reaction.

  The weight ratio, most preferably, of chloromethyl methyl ether to the crosslinked copolymer is about 5/1. The catalyst preferably used is Sn C 14 because of its catalytic ability and ease of treatment after chloromethylation. The catalyst is usually in the range of 0.5 to 30 parts by weight per 100 parts by weight of chloromethyl methyl ether and is chosen

  suitably depending on the desired level of chloromethylation.

  In general, the reaction is carried out at a temperature of 0 to 580 ° C.

  (boiling point of chloromethyl methyl ether).

  The chloromethylation level of the copolymer is preferably

  chloromethyl groups for 10 aromatic units.

  At the end of the chloromethylation, the chloromethyl groups are converted to methylol groups (-CH 2 H) by alkaline hydrolysis at room temperature or higher. In the H 20 / NaOH system, the reaction rate is low and the reaction rate is low. addition of methanol accelerates the reaction The alkali concentration, the amount of methanol, the temperature and the reaction time are chosen according to the introduction rate

methylol groups.

  The supports according to the present invention have their outer surface strongly hydrophilic therefore they can disperse easily

  in an aqueous medium The inner surface of the pores of the support is also

  However, to a lesser extent than the outer surface, hydrophilic substances of low molecular weight can freely penetrate the pores. The inner surface of the pores bears only methylol groups but is fixed by a non-water-soluble polymer and is

  less hydrophilic than the outer surface.

  The degree of hydrolysis of the chloromethyl groups is preferably about 1% or more. The number of methylol groups introduced into the substrate is

  therefore from 0.1 to 0.5 per aromatic unit.

  The viscosity of the supports of the invention is so low that a high flow rate can be obtained in a packed column of the support for

  high-speed liquid chromatography In addition, in the chromato-

  high-speed liquid chromatography, good reproducibility and good fractionation of low molecular weight hydrophilic substances are obtained. The carriers of the present invention capable of excluding substances having a molecular weight of less than 30,000 and having a diameter of 1 to 30 p are preferably used for the analysis of low molecular weight hydrophilic substances, in particular those which are found in samples containing high molecular weight substances, for example, serum proteins, because they can not absorb these high molecular weight substances and therefore,

  they can be used for the continuous analysis of such samples.

  On the other hand, the supports of the invention, capable of excluding substances of a molecular weight of at least 30,000 can be used in various fields, for example as supports for the separation of hydrophilic substances from low molecular weight, for removal of proteins before entry into the column, for antigen-antibody reactions and the like, as they are able to fully absorb high molecular weight substances such as hydrophilic proteins In this case, the diameter of this support may be between 1 and 300 p, although it is preferable that this diameter is

  between 1 and 30 if it is desired to use it in the columns of

  for the analysis of hydrophilic substances of low molecular weight.

  The invention will be better understood by reading the

  following examples given for illustrative but non-limiting.

EXAMPLE 1

  A solution of 12.5 g of methyl cellulose in 625 g of water containing 0.125 g of sodium lauryl sulfate is introduced into an autoclave and after addition of 21.8 g of styrene, 18.2 g of divinylbenzene and 60 g of toluene. , as a pore regulator, in the autoclave, the polymerization is initiated by the addition of benzoyl peroxide and is carried out

  the polymerization at 600 C for 17 h with vigorous stirring.

  The polymer is washed well with water and then with acetone. The washed polymer is dried at 400 ° C. under reduced pressure. The diameter of the dry polymer is of the order of 3 to 20 μ. By subjecting the polymer to sieving,

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  grains of 10 to 20 μm in diameter are collected. The molecular weight excluded by these polymers is of the order of 7,000; it is determined by means of polystyrene of known molecular weight using tetrahydrofuran

as an eluent.

  5 g of grains and 1.5 ml of anhydrous tin tetrachloride are added to 35 ml of chloromethyl methyl ether, and the mixture is heated under reflux condenser for 6 hours at 50-60 ° C. The color of the grains becomes darker,

  black-brown with the progress of the reaction.

  It is finished, the grains are washed several times in methanol charged with hydrochloric acid, then with acetone until they take an ocher yellow color. The degree of chloromethylation of the grains is about 62 chloromethyl groups. per 100 aromatic groups;

  this rate is determined by comparing the infrared absorption bands (I.

  at 1600 cm-1 due to aromatic groups and at 1260 cm due to chloromethyl groups, to a calibration curve obtained from mixtures

  cumene and p-iso-propyl benzyl chloride in various proportions.

  The chloromethylated grains are heated in a 10% aqueous solution

  of sodium hydroxide at 60 ° C for 9 hours to effect the hydrolysis.

  The intensity of the IR absorption band at 1260 cm -1 of the hydrolysed grains, due to the chloromethyl group, is decreased and, on the other hand, an absorption band at 1090-1100 cm -1 of the CO group appears. From the decrease in intensity of the band at 1260 cm -1, it is deduced that about% of the chloromethyl groups have been converted into methylol groups, i.e.

  introduced into the grains 34 methylol groups per 100 aromatic units.

  The grains obtained according to the present invention disperse

  extremely well in water and in various buffer solutions without coagula-

  lation or apparent agglomeration.

  After filling a stainless steel tube, 4 mm in diameter and 500 mm long, the support of the invention is subjected to 20 pt of a mixture

  of p-aminobenzoic acid, creatinine and uric acid to a chromato-

  on this column using an aqueous phosphor buffer solution of 1/20 N as eluent. The chromatography is carried out under the following conditions: ultraviolet detector and set at 250 nm, elution rate 1 ml / min and pressure 20 bar. Elution time is 10.4 min for p-aminobenzoic acid, 7.5 min for creatinine and 5.5 min

for uric acid.

  Moreover, chromatography is carried out on a mixture of albumin of beef serum and of the three compounds above, on the same column Albumin rises first and the four substituents are perfectly separated from each other (cf. Figure 1, which gives

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  the elution curve) When the chromatography is repeated, only a slight adsorption of the albumin during the first and second repetitions is observed, and then at all thereafter.

  almost the same results later.

  It is thus found that the carrier of the present invention is quite suitable for the analysis of water-soluble low molecular weight substances and does not adsorb high molecular weight proteins.

COMPARATIVE EXAMPLE 1

  After having filled the same stainless steel tube with the polymer prepared according to the process of Exempt 1, but not yet chloromethylated,

  the same sample as in Example 1 is subjected to chromatography.

  The pressure rises above 80 bar for a flow rate of 1 ml / min, which indicates a significant effect of the viscosity of the methyl cellulose attached to the inner surface of the polymer pores. The four constituents of the sample almost no separate from each other and they

elute very quickly.

COMPARATIVE EXAMPLE 2 -

  59 of polymer of Exempt 1 are subjected to chloromethylation according to the procedure of Example 1, except that the reaction time is 24 hours instead of 6 and grains having a degree of chloromethylation of about 64% are obtained. The grains are hydrolyzed in a solution of 25 g of NaOH in 100 g of methanol, 60% for 15 h to obtain a support having

  about 58 (average) methylol groups per 100 aromatic groups.

  After having filled the same stainless steel tube as in Example 1 with the support, a mixture of albumin of beef serum, p-amino-benzoic acid, creatinine and uric acid is subjected to chromatography. on this column, with the same eluent at a flow

  1 ml / min; the following elution times are found: p-amino acid

  benzo & that 6.4 min; creatinine 5.9 min and uric acid 4.8 min. So the elution time is shorter than in Exempt 1 and

  p-aminobenzoic acid can not be separated from creatinine.

  The elution curve of this chromatography is shown in FIG.

  These results show that the interaction between hydrophilic substances of low molecular weight and the internal surface of the pores of the support is greater in the support of the invention than in the support.

of this Comparative Example No. 2.

EXAMPLE 2

  By operating according to the protocol of Example 1, 21.8 g of styrene and 18.2 g of divinylbenzene were polymerized in the presence of 56.4 g of toluene and 3.6 g of n-dodecane as a pore to obtain a styrene / divinylbenzene copolymer for which the molecular weight

  excluded is of the order of 16 000. The copolymer is chlorinated

  methylation under the same conditions as in Example 1, except that a reaction time of 2 hours instead of 6 is adopted, to obtain a chloromethylated copolymer whose chloromethylation rate is about 42 chloromethyl groups per 100 aromatic units The copolymer is hydrolyzed in a 10% aqueous solution of sodium hydroxide at 60 ° C. for about 5 hours; we get a support that includes, on average,

  about 20 methylol groups for 100 aromatic units.

  The same column as in Example 1, filled with this support, is under a pressure of about 25 bar for an elution rate of 1 ml / min of aqueous phosphoric buffer M / 20. p, a mixture of uric acid, creatinine and p-aminobenzoic acid has a chromatography on this column The three constituents separate perfectly A test carried out on a mixture of albumin of beef serum and these three constituents show that

  albumin is not adsorbed at all.

EXAMPLE 3

  2 g of methyl cellulose are dissolved in 125 g of water and 0.025 g of Na lauryl sulphate are added. After introducing this mixture into

  a 300-ml flask was added 3.27 g of styrene, 2.73 g of divinyl-

  benzene and 6.75 g of toluene and 2.25 g of n-dodecane as a pore regulator and then the mixture is stirred at 60 ° C. for 17 hours in the presence of benzoyl peroxide to initiate the reaction. water, then acetone and dried at room temperature under reduced pressure The diameter of the spherical grains is substantially uniform and

about 20.

  The molecular weight excluded by these grains is of the order of 100,000; this value was established by eluting polystyrene of molecular weights

  varied on a column packed with these grains.

  5 g of these grains are placed in a flask and 35 ml of chlorine are added.

  methyl methyl ether and 1.5 ml of anhydrous Sn C 14 The mixture is refluxed at 60 ° C. for 6 hours in order to chloromethylate the grains.

  gradually dark brown with the progress of the reaction.

  At the end of the reaction, the grains are washed with methanol containing

  hydrochloric acid, several times, then with acetone.

  The final color of the grains is yellow-brownish. New absorption bands appear at 1260 and 670 cm-1 in the infrared spectrum of the grains after chloromethylation. The chloromethylation rate is approximately

  chloromethyl groups per 100 aromatic units.

  Oh pour the grains in a solution of 259 of NaOH in 100 ml

  of methanol and this mixture is allowed to react at 60 ° C. for 15 hours.

  We see a new infrared absorption band at 1090 cm-1 due to the introduction of CH 20 H groups.

  methylols per 100 aromatic units.

  The grains are carefully dispersed in water, various solutions

  tampons, urine, etc., without noting aggregation.

  These grains are packed with a 4 mm stainless steel column

  of diameter and 500 mm long for high speed liquid chromatography.

  This column is subjected to a solution of albumin serum albumin in M / 20 phosphoric buffer at high speed liquid chromatography; eluted with this phosphoric buffer at a flow rate of 1 ml / min Elimination of albumin is not observed Moreover, the elution of albumin is not observed even after passing 50 μl of albumin

  of 10% beef serum fifty times in a row.

  A 20 μl sample of a solution of uric acid, creatinine, p-amino benzoic acid and albumin in a M / 20 phosphoric buffer is passed through the column. uric, creatinine and p-amino-benzoic acid from each other without eluting albumin. Figure 3 shows a record of elution peaks for a paper unwinding speed of 10 cm / 3 min, measured at a wavelength of 250 nm The pressure is 25 bar for a flow rate of

1 ml / min.

EXAMPLE 4

  A styrene-divinylbenzene copolymer is prepared as in Example 1 except that 459 toluene and 15 g of n-dodecane are used as pore regulators, instead of 60 g of toluene. The molecular weight excluded by the polymer obtained is In the order of 100,000, methylol groups are introduced into the polymer as in Example 1; the final rate

  is about 40 methylol groups per 100 aromatic units.

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  After having packed the tube as in Exempt 1 with the support obtained, albumin is subjected to chromatography. Albumin is

  absorbed by the column and it is not eluted.

COMPARATIVE EXAMPLE 3 -

  A styrene / divinylbenzene copolymer is prepared according to the protocol of Example 3 except that 13.9 g of calcium phosphate and 4.07 mg of sodium n-dodecylbenzenesulfonate are used instead of methyl cellulose and Sodium lauryl sulfate of Example 3 After washing with Au, the copolymer is sieved to obtain grains with a diameter of 10 to 20 percent. However, the range of diameters is wide The molecular mass excluded

is in the order of 100,000.

  The grains are carefully washed with hydrochloric acid to remove calcium phosphate The grains do not disperse at all

  in water and they remain agglutinated.

  After drying the grains, the chloromethylation is carried out

  in Exempt 3 The grains are slightly colored in light yellow.

  The chloromethyl groups are converted into methylol groups as in Example 3 The grains obtained are less hydrophilic than those of the Exemp Le 3 and they do not disperse well in water or in the urine. not completely adsorbed on a column packed with these grains and we obtain a very large peak of albumin It is thought that it is because the grains are less hydrophilic than those of the Exempte 3

  and that the proteins can not penetrate the pores.

EXAMPLE 5

  Small styrene-divinylbenzene copolymer grains, capable of excluding molecular weights of 300,000, are prepared as in Exempt but using 4.5 g of toluene and 4.5 g of n-dodecane to regulate the pores on treats the grains as in Example 3 to obtain supports having methylol groups The support obtained sedisperse well in serum and in urine Elution of albumin is not observed with a column packed with these grains even when samples of 50 μl of 10% albumin solution are passed 50 times

of beef serum.

Claims (22)

  1. Porous support for the analysis of hydrophilic substances of low molecular weight, characterized in that it consists of a crosslinked copolymer containing methylol groups, this copolymer being obtained from monomers of the styrene series and an agent crosslinking   copolymerizable with the monomer, in that its external surface is hydrophilic   and in that the inner surface of the pores is hydrophobic.   2. Support according to claim 1, characterized in that the monomer   is V-methylstyrene, chloromethylstyrene, styrene and combinations thereof.   3. Support according to claim 1 or 2, characterized in that the crosslinking agent is divinylbenzene, trivinylbenzene, triallyl isocyanurate, dimethacrylates and diacrylates of polyhydric alcohols and diallyl phthalate.   4. Support according to claim 1, characterized in that the copo-   The polymer is a styrene-divinylbenzene copolymer.   5. Support according to any one of claims 1 to 4, characterized   risé in that it consists of spherical grains with a diameter of 1 to p about.   6. Support according to any one of claims 1 to 5, characterized   in that the molecular weight excluded by these supports is inferred to 30,000.   7. Support according to any one of claims 1 to 5, characterized   in that the excluded molecular mass is greater than 30 000,   and in that it is capable of adsorbing proteins.   8 Support according to any one of claims 1 to 7, characterized   in that it comprises 10 to 50 methylol groups per 100 aromatic units.   9. Support according to any one of claims 1 to 8, characterized   in that it is used for liquid chromatography.   Process for the preparation of a porous support for the analysis of hydrophobic substances of low molecular weight, characterized in that a mixture of a monomer of the series of styrene and a   crosslinking agent copolymerizable with this monomer, to a polymer   in suspension in water in the presence of a pore regulator and a water-soluble polymer, and in that methylol groups are   on the resulting crosslinked copolymer.   11. Process according to claim 10, characterized in that the monomer is styrene, α-methylstyrene, chloromethylstyrene and their combinations.   12. Process according to claim 10 or 11, characterized in that the crosslinking agent is divinylbenzene, trivinylbenzene, triallyl isocyanurate, dimethacrylates and diacrylates of alcohols   polyhydroxyls and phthalate dediallyl.   13. The method of claim 10, characterized in that the   monomer is styrene and the crosslinking agent is divinylbenzene.   Process according to any one of claims 10 to 13,   in that the proportion of crosslinking agent is 30 to 70% of   total weight of mixture of monomer and crosslinking agent.   15. Process according to any one of claims 10 to 14,   characterized in that the water-soluble polymer is a polyethylene oxide, saponified polyvinyl acetates, polyvinyl alcohol, polyvinyl pyrrolidone and methyl cellulose.   16. A method according to any one of claims 10 to 15, characterized   characterized in that the proportion of water-soluble polymer is 5 to 60 parts by weight per 100 parts by weight of the monomer mixture and crosslinking agent.   17. The method according to claim 16, characterized in that the   portion of water-soluble polymer is between 10 and 40 parts by weight per 100 parts by weight of mixture of monomer and crosslinking agent.   Process according to any one of claims 10 to 17,   characterized in that the placement regulator is an organic solvent inert soluble in the monomer.   19. The method of claim 18, characterized in that the pore regulator is an aromatic hydrocarbon such as benzene, toluene and xylene, chlorinated hydrocarbon such as trichlorethylene, chloroform and carbon tetrachloride, an aliphatic hydrocarbon   such as n-hexane, n-heptane, n-octane and n-dodecane.   20. Process according to any one of claims 10 to 19,   characterized in that the proportion of pore regulator is from 20 to 300 parts by weight per 100 parts by weight of mixture   monomer and crosslinking agent.   21. Process according to any one of claims 10 to 20,   characterized in that the resulting crosslinked copolymer receives groups   methylols by chloromethylation of the copolymer followed by hydrolysis.   22. Support according to any one of claims 1 to 9, obtained   by a process according to any one of claims 10 to 21.