DE1000682B - Process for the production of absorbent paper for chromatographic purposes with special properties with regard to the separation effect - Google Patents

Description

Process for the production of absorbent paper for chromatographic Purposes with special properties with regard to the separating effect The invention relates to paper for chromatographic separations. The chromatographic separation Smallest amounts of substance with the help of paper chromatography is more recent a valuable method for the determination and isolation of the most diverse chemical compounds.

The papers previously used for paper chromatography are special pure filter papers z. B. from cotton fibers, cellulose pulp. Like. Manufactured and have particularly good absorbency and high strength properties. It is also possible to use other fibrous materials, such as. B. glass fibers, slag wool, synthetic fibers and the like, to be used for the production of the absorbent paper.

The previously common paper chromatography works according to the principle partition chromatography.

In some publications, the term adsorption chromatography is also used. There are usually two liquid phases, namely the water-containing organic phase Solvent in which the mixture of substances to be separated is dissolved, and the one with it organic solvent saturated water that adsorbs on the paper fiber is. The more soluble a substance is in the water-rich phase, the stronger it is if it adheres to the fiber, the slower it migrates in the chromatogram. The heavier A substance is soluble in the aqueous phase, the faster it becomes with the organic solvents migrate through the paper, so the substances are separated based on their solubility. If one calculates with adsorption processes in paper chromatography, This is also how the different Adsorptionskoeffizien the substances play in the separation a role.

To the separation of vitamin A alcohol and its esters with use To be able to carry out paper soaked with aluminum sulphate has also already been done suggested developing these papers with petroleum ether. It is here also just about the usual distribution or adsorption processes, which are also involved in a known chromatographic paper soaked with silica.

The invention extends to absorbent paper for chromatographic Separations, which is characterized by the fact that in this chemical substances fine and are evenly distributed, which in themselves have exchanger properties or impart such properties to the absorbent paper. So can for example high molecular weight organic substances that have exchange properties in the Chromatography paper made of absorbent paper should be incorporated, whereby those in either acidic or basic form substantive to the paper fibers raised are, or as organic fillers, synthetic resins or the like. The exchange property have, are added to the paper stock .. Instead of such substances can also inorganic substances which give the chromatography paper exchange properties lend, be finely distributed in the paper stock.

In the chromatography paper according to the invention, the separation takes place in a completely different way than in the previously known distribution or adsorption chromatography. The solution interacts with the solid phase. They practice on paper existing additives which have exchange properties or those of the paper confer specific effects on ionogenic substances, e.g. B. hold carboxyl groups alkaline substances, while they pass through neutral and acidic substances unhindered let, d. H. So, with the new papers, mixtures of substances are created on the basis of their different basicity or acidity separately.

The manifold possibilities when using ion exchangers are common, can be transferred according to the invention to paper chromatography. The purely external handling of the chromatography papers with exchange properties is the same as with the previously usual chromatography papers, you can ascend, work in descending order or in a ring chromatogram. One develops the substance mixtures to the chromatogram with aqueous or organic solvents, which on a certain p-value and are adjusted to a certain ion concentration by adding salt. The achieved release effect is dependent firstly on the exchange capacity and the nature of the exchanging groups in the paper, secondly the PH and the ionic species and ionic strength of the so-called developing solution.

The field of chromatography is greatly expanded when in addition to partition chromatography respectively.

Adsorption chromatography according to the invention still has the separating effect is made usable by ion exchange in paper chromatography. Special 4ers It has a beneficial effect that one also uses the exchanger chromatography paper can work with purely aqueous solvent, which was the case with previous paper chromatography was only possible in exceptional cases.

The following can be separated on the paper according to the invention, for example: Amines, alkaloids, carboxylic acids, amino acids, dyes of various basicities, Phenols, heterocycles with nitrogen as the heteroatom and inorganic cations.

The attempts that have been isolated so far in the literature, active exchange Papers to use for chromatographic separations laid out from the usual chromatography p ap ier partially impregnation with water-soluble substances, z. B. Phosphates. Such papers show when developing the chromatograms Exchange effect with organic solvents, because of the water solubility of the However, the process is not suitable for substances used for impregnation direct production of exchange papers. Finished sheets of paper were also tried partly by esterification reactions with cellulose derivatives, e.g. B. with carboxymethyl groups, equip. Again, this procedure is cumbersome and time consuming, and it does Difficulties in producing paper that contains the exchange-active cellulose derivatives contains evenly distributed and in its paper properties, e.g. B. absorbency, Smoothness, strength, is not damaged.

In the earlier German patents 907 737 and 944 347 is already been proposed, the absorbent paper oxycellulose, which by Effect of oxidizing agents on cellulose fibers was obtained in the finest possible way To add distribution, namely the oxycellulose is to be added according to a special process for the purpose of even distribution in the finished paper before or after the entry in the paper pulp completely or partially converted into a water-soluble alkali compound and from this the oxycellulose is obtained by a suitable water or acid treatment to precipitate and fix on the fibers.

Such oxycellulose papers for chromatographic purposes are in excluded from the present invention.

The chromatography papers according to the invention are according to the following Process produced: 1 a Mixing of acidic or basic substances with a fiber structure to pulp.

Ib admixing non-fibrous fillers to the pulp.

2a Core impregnation by adding the substances in dissolved form to the Pulp pulp and subsequent precipitation on the fiber.

2b surface impregnation by spraying on the substance solution the paper web being formed or finished or exchanging the same with subsequent one Precipitation in the precipitation bath or evaporation of the solvent.

For the production of chromatography paper with exchange properties according to the invention can the following substances are used: cellulose derivatives, except Oxycellulose, namely carboxymethyl cellulose, acidic cellulose esters such as cellulose sulfate, cellulose phosphate, cellulose phthalate, maleate, succinate; nitrogenous or sulfonic acid-substituted cellulose ethers, as they are known per se Way receives, e.g. B. from alkali cellulose and appropriately substituted chloroethanes or ethylsulfuric acids. The solubility of highly substituted products of this type can be known to reduce by crosslinking reactions z. B. with glyoxal or dichlorohydrin.

The above-mentioned cellulose derivatives are ion exchangers which are in accordance with Invention suitable for admixture to the paper stock, its production itself is outside of it of the claims of this patent.

The paper according to the invention can also incorporate high molecular weight Carboxylic acids such as alginic acid, pectin, tannin or hardened protein types, such as. B. Formalin treated casein. Colorless fillers can also be used inorganic oxides or hydroxides, such as. B. zinc oxide, magnesia, lime. Furthermore can organic acids which are insoluble in water are mixed in, e.g. B.

Naphthoic acid, terephthalic acid, higher fatty acids, naphthylamine sulfonic acid, Sulfanilic acid, benzidine disulfonic acid and finely powdered synthetic resins with exchange properties, as they are commercially available in various gradations of acidity or basicity.

For core and surface impregnation for chromatography Paper used according to the invention are suitable among the substances mentioned so far all those that are added to the paper pulp in dissolved form and then through Change in the pH value or precipitated on the fiber by displacing the solvent can be, e.g. B.

Carboxymethyl cellulose, alginic acid, pectin, tannin, water-insoluble organic acids or inorganic hydroxides. In addition, high molecular weight substances Find various types of use, which as such refer to the paper fiber as a substantive or in a paper-fiber mixture by condensation or polymerisation develop. Examples are formaldehyde condensation products of melamine or hexamethylenediamine, water-insoluble polyacrylic acid compounds or polyethyleneimines. So far, such impregnation additives have only been used to wet paper Paper pulp or for the finished paper has become known, but not for chromatography papers.

The separation effect of the chromatography paper according to the invention is essentially dependent on the content of active exchange groups in the paper. The amount on added or in the pulp generated exchange substance can be with vary within wide limits for the specific purpose. Generally one works today with exchange capacities of O, OI to 0.2 equivalents per m2 of paper. You get such exchange-active chromatography papers whose acidity or

Basicity due to the chemical properties of the exchange substance, whose capacity is determined by the amount of additive. In special cases can be used to separate mixtures of substances, the acidic, neutral and basic substances use papers that contain both acidic and basic additives. The two interchangeable substances can be in the same or in the paper mutually different quantitative ratios exist.

The table below shows how the various possible substances are distributed among the manufacturing processes in question: Sour basic Yes Admixing fiber conveying miger products: Carboxymethyl cellu- aminoethyl cellulose loose Cellulose phosphate Cellulose phthalate maleinat CeleluLosephthalate succinate Alginic acid away. Admixing non-fiber shaped fillers: Tannin hardened casein powdered cation powder powdered anion exchanger exchange resins resins water-insoluble or- zinc oxide ganic acids 2a. Core impregnation: Carboxymethylcellu-polyethyleneimine loose formaldehyde condensate Alginic acid products from Mela Tannin nin, hexamethylene water-insoluble color amine organ. Acids Zn (OH) 2, Al (OH) 3 2 B. Surface impregnation renation: same substances as 2a.

In the admixing process (ia and Ib) to the pulp one becomes generally the cation exchangers in the acidic, the anion exchangers in add to the basic form. This requires that you have the exchange-active substances often has to undergo pre-treatment. The cation exchangers (Ia and Ib "acidic") are usually treated with dilute mineral acid with pi values below 4, the anion exchangers (Ia and Ib "basic") with dilute alkalis at pE values Treated via IO and then thoroughly washed out with water. The mixing pulp preparation itself can take place at any time. Usually One becomes finely fiberized exchange substances or those that are slightly slimy become clogged only after grinding, while coarse-grained, more difficult to spread expediently be added before or during milling. Take cation exchanger eager to heavy metal ions, one therefore has to grind such substances into corrosion-resistant Units to perform.

Non-fibrous fillers (1b) are best before mixing finely powdered. It is essential for the later separation effect of the chromatography paper, that the exchange-active fillers are very fine-grained and evenly in the pulp are distributed.

The production of the absorbent paper with the mixed finely divided Substances takes place in a manner known per se.

Such substances are used for core and surface impregnation, which are soluble in the form of their salts. Substances of this type listed under 2a and 2b Are called "acidic", the substances become 2a through subsequent acidification and 2b "Basic" precipitated by the subsequent addition of alkalis to the fiber (Type A). Furthermore, among other things, substances are also used that are substantive by type Dyes can be absorbed onto the fiber without changing the p-value, such as B.

Polyäthylenimine suitable degree of polymerization (type B), or which only arise through condensation or polymerization in the pulp, such as z. B. the formaldehyde condensation products mentioned under 2a "basic" (type C).

The impregnation process depends on the type of substance used a little different. In principle, the addition of the aforementioned solutions to each Time of fabric processing, d. H. by adding to the pulp or paper pulp (»Core impregnation«) or by applying it to the or finished paper web (»surface impregnation«).

With substances that are soluble in the form of their salts (type A), works it is best to use equivalent quantities, i. H. it is first added to the pulp the solution of the salt, mixes well and now sets the to precipitate the free Acid or base just necessary, d. H. equivalent amount of mineral acid or alkali to. This avoids too high a neutral salt content in the pulp. If you want to produce paper with such substances that are completely free of Neutral salts, so you have the paper stock after the core impregnation, before it is Paper mash has come to be washed thoroughly again.

The absorption of substances like substantive dyes pulling on the fibers (type B) requires a certain amount of core impregnation Dwell time. In the case of substances that only result from condensation or polymerisation reactions arise in the paper pulp (type C), it is important that the solution of the one Reaction partner (e.g.

Hexamethylenediamine) is first evenly distributed in the pulp, before the substance that triggers the reaction (e.g. formaldehyde) is added. In all three cases (A, B and C) the addition can be before, during or after grinding or can also be done by applying to the paper web.

There is another possibility for core and surface impregnation in the fact that one with substances that have exchange properties or such give the paper the acids in their acidic and the bases in their basic Bringing the form into solution and adding it to the pulp (type D).

Hot water and water-miscible organic solvents are used as solvents Solvent in question.

The dissolved substances are then precipitated onto the fiber either when cooling the water or when diluting the organic solvent with Water. The addition can be restored at any time during fabric processing or by applying to the paper web.

Another method that is preferably used for surface impregnation suitable consists in using substances of the aforementioned type in volatile solvents dissolves and applies to the paper web.

The solvent evaporates in or in the dryer section specially set up drying system, as z. B. of paper coating machines is known ago, and the active exchange substance is deposited on the fiber.

In general, those used in the paper industry for surface impregnation common application devices, such as B. size presses, applicator rollers or Spray pipes of various arrangements, find use.

Usually it will be sufficient to carry out the order on one side only. Using of substances that are soluble in the form of their salts and by subsequent acidification or alkalizing on the fibers are precipitated, or such substances, which arise through condensation or polymerization are two separate from each other Impregnation steps required, as these are precipitation reactions.

From the foregoing it follows that those for core impregnation are as follows given application examples II to I3 without further ado to the surface impregnation process Can be transferred, like examples Iq and I5, as surface impregnation are described, can be carried out analogously as core impregnation.

As already mentioned, the paper according to the invention contains the exchange-active ones Substances are mostly not in the form of their salts, but the cation exchangers in the acidic form, the anion exchangers in the basic form. But now Ion exchangers not only as free acids or

Bases, but also in the form of their salts, are effective, it is in In some cases it is possible that the substances have exchange properties or give those to the paper, are present in the paper in the form of their salts. The case can occur when the active exchange substance is insoluble in water as a salt is.

So z. B. cellulose phosphate, phthalate, maleate, succinate and low-substituted carboxymethyl cellulose to the paper readily in the form the alkali or alkaline earth salts are added (method Ia), including the admixing of pulverized exchange resins in the salt form does not cause any difficulties (Method Ib). The active exchange substances in question are prior to admixing pretreatment: the cation exchangers are known to be best with alkali salts weak acids, the anion exchangers with hydrochloric acid salts are weaker Bases converted into the alkali or hydrochloric acid salts (cf. following application example 1 b).

An u-endunfsbeispiele 1. To 5 parts by weight of the for the preparation pulp suitable for absorbent paper is dissolved in 94 parts by weight of water I part by weight of fibrous carboxylmethyl cellulose was added. The carboxymethyl cellulose is converted into the free acid beforehand with dilute mineral acid. The addition to pulp takes place before milling. The finished paper contains about 10% Carboxyl groups based on the paper.

2. 5 parts by weight of fibrous material are added to 94 parts by weight of water suspended. After grinding, I part by weight of cellulose phthalate (with 7% acidic content) added. The finished paper contains 0.70 / a phosphorus, based on paper. The cellulose phosphate can be produced in a known manner, e.g. B. by Erhit en of cellulose with phosphoric acid and urea if I500, and lies as dibasic acidic ester.

3. Ti 94 parts by weight of water are suspended 5 parts by weight of fiber. After grinding, part by weight of cellulose phthalate (with 70/0 acidic carboxyl groups) added. The finished paper contains 0.70 / 0 carboxyl, based on paper. There:) Cellulosephtbalat is known in a known manner, for. B. by Esterifying cellulose with Phthalic anhydride in glacial acetic acid, produced and available as a half ester.

. It is added to 5.3 parts by weight of fiber in 94 parts by weight of water 0.7 parts by weight of fibrous alginic acid. The alginic acid was previously by repeated Treatment with dilute mineral acid converted into the free acid. The addition takes place before grinding. The finished paper contains 1.8% carboxyl groups, based on on paper.

5. 10 parts by weight of 2-chloro-I-dimethylaminoethane hydrochloride will be in 15 parts by weight of acetone and 1 part by weight of 20% sodium hydroxide solution with 35 parts by weight Alkali cellulose implemented. NIan mixes the thoroughly washed reaction product equal parts of the milled pulp suitable for the production of absorbent paper and suspended in 300 parts by weight of water. The finished paper contains in IOO g 20 basic exchange milliequivalents.

6. Mix to 4 parts by weight of fiber in 94 parts by weight Water 2 parts by weight of finely powdered anion exchange resin. The exchange resin was previously pretreated several times with 10% sodium hydroxide solution and contained 1.5 exchangeable Milliequivalents per g. The addition can be made before or after grinding. The finished one Paper contains 100 g o milliequivalents of basic exchange substance.

7. The pulp is finely pulverized 3 0/0 (based on fabric) Zinc oxide added before or after grinding. The finished paper contains 100 g 200 exchange millie equivalents.

8. 15% (based on the fabric) naphthylamine sulfonic acid are added to the pulp added before or after grinding. The finished paper contains I O / o sulfonic acid groups, based on paper.

9. In 94 parts by weight of water there are 5.6 parts by weight of ground Pulp. At 500, 0.4 parts by weight of sodium stearate are added in 1 part by weight Dissolved water, fills with calcium acetate and carries the precipitated on the fiber Calcium stearate is converted into the free acid with dilute hydrochloric acid. The paper contains o, GO / o exchangeable carboxyl groups, based on paper.

10. 0.6 parts by weight of tannin are dissolved in dilute sodium hydroxide solution and added to 5.4 parts by weight of ground pulp in 9+ parts by weight of water.

It is acidified to pole 2 ah with dilute hydrochloric acid and washed thoroughly with water. The fiber material pretreated in this way is dissolved in 94 parts by weight of water Paper machine fed. The finished paper contains 10/0 carboxyl groups, based on on paper.

1 1. 0.2 parts by weight of sodium alginate (with 9% Na) are in 94 Parts by weight of water dissolved. 5.8 parts by weight are suspended in this solution ground pulp and adds 0.1 part by weight of concentrated hydrochloric acid. Of the Pulp is fed to the paper machine without further washing. The finished one Paper contains 0.5% carboxyl groups.

I2. To a pulp which in 9+ parts by weight of water 6 parts by weight Contains fibrous material, you add o "parts by weight of hexamethylenediamine, mix well and then adds 0.2 parts by weight of formaldehyde in a 300% solution. The finished one 100 g paper contains 65 milliequivalents in exchange.

13. To a pulp suspension in 94 parts by weight of water Contains 6 parts by weight of ground pulp, 0.3 parts by weight of a 50% solution of polyethyleneimine. Leave to stand overnight. The finished paper contains 0.36 ovo basic nitrogen, based on paper.

14. A hot 100% aqueous solution is applied to the paper web of sulfanilic acid. The application is carried out in such a way that the moist web has 2 01o sulfanilic acid (based on dry matter) absorbs. The finished paper contains about IO / o active exchange Sulfonic acid groups.

I5. The paper web is coated with an ammoniacal solution of zinc hydroxide soaked (1.5% Zn based on paper). The ammonia is expelled by heating to IIO to I20 ° and thereby precipitates zinc hydroxide on the fiber. The finished one Paper contains 1.50 / 0 Zn.

I6. I part by weight of cellulose phosphate (with 8 0 / o phosphorus content) Treated several times with concentrated sodium acetate solution and then thoroughly with Water washed. The sodium salt of cellulose phosphoric acid thus obtained becomes 5 parts by weight of ground pulp mixed in 94 parts by weight of water. That finished paper contains 1 0/0 phosphorus, based on paper.

Claims (8)

PATENT CLAIMS: I. Process for making absorbent paper for chromatographic purposes with special properties with regard to the separation effect, characterized in that the paper pulp or the moving paper web is chemical Substances are added that have ion exchange properties or impart such properties to the absorbent paper, with the exception of oxycellulose as an additive. 2. The method according to claim I, characterized in that fibrous Substances that have exchange properties are added. 3. The method according to claim I, characterized in that water-insoluble organic acids, organic fillers, synthetic resins or the like with exchange properties can be added. 4. The method according to claim I, characterized in that organic Substances that have exchange properties or give the paper in dissolved form Form can be added and drawn onto the fiber by precipitation. 5. The method according to claim I, characterized in that high molecular weight Organic substances are added which, after condensation or polymerization, the Give exchange properties to paper. 6. The method according to claim I, characterized in that metal hydroxides or oxyhydrates, which give the paper exchange properties, are added will. 7. The method according to claim I and 6, characterized in that metal salts are added and their hydroxides or hydrated oxides by precipitation on the fiber to be pulled. 8. The method according to claim I, 4 and 6, characterized in that the substances to be added are brought into solution on the paper web and then through Evaporation of the solvent can be thrown onto the paper. Publications considered: C r a m e r, paper chromatography, 2nd edition, p. 109; German patents nos. 907 737, 944347.