The method of producing plates for thin-layer chromatography

 

(57) Abstract:

The invention relates to analytical chemistry. The invention can be used for analysis of multicomponent mixtures, division and separation of their components in medicine, pharmaceuticals, chemical, microbiological and food industry. The method of producing plates for thin-layer chromatography involves the pre-processing of metal foil applied to the suspension of the adsorbent with a binder, drying the plate. The metal foil is treated at room temperature 1 - 8% aqueous solution of water glass containing 0.5 to 2.0% of sodium hydroxide or potassium. The invention allows to obtain a plate of high quality reusable.

The invention relates to analytical chemistry, more specifically to a method for producing plates for thin-layer chromatography /TLC/.

The invention can be used for analysis of multicomponent mixtures, division and separation of their components in biochemical research, medicine, agriculture, pharmaceutical, chemical, microbiological and food industry.

Plate for TLC consists of a base-vile is tography. H. 1. M.: Mir, 1981/. A substrate made of glass, plastic films, aluminum foil. Aluminum foil has several advantages. Compared to polymer films it is more durable and resistant to aggressive environments and temperature upon receipt, use, and regeneration of the plate. Compared with glass substrates aluminum foil considerably more durable, convenient organization of continuous process production of plates for TLC, it cannot be broken during transportation and, finally, it can be cut with scissors.

A method of obtaining plates for TLC by degreasing the aluminum foil by washing with soapy water, drying the foil, causing the foil aqueous slurry of adsorbent selected from the group consisting of aluminum oxide, silica gel, diatomaceous earth, polyamide or cellulose powder and polymer binder: polyvinyl alcohol, starch, mixtures of gelatin and polyvinyl alcohol, gelatin or cellulose derivatives, polyvinyl acetate, polyvinyl butyral, epoxy, melamineformaldehyde resins. The plate is dried, while harden, the adsorbent is bonded to substrate /U.S. Patent 3418158, CL 210-192.2, 1965/.

Polymer binder nafie mechanical strength. However, the presence of one or another binder creates additional restrictions in the selection of the solvent system and the choice of the developer when chromatographicaliy. Thus, the presence of starch as a binder not possible to demonstrate a chromatogram in iodine vapor or by using concentrated sulfuric acid. The presence of a polymeric binder does not allow you to work at a temperature of more than 100oC exhibiting a mixture of the potassium permanganate - sulfuric acid.

Plate, obtained by the known method cannot be regenerated by treatment of a chromium mixture due to charring of the organic binder and, therefore, to reuse.

When transporting wafers obtained in a known manner, there is cracking and peeling of the adsorbent.

A method of obtaining plates for TLC by degreasing the substrate is aluminum foil, applying aqueous slurry of the adsorbent, phosphor, facilitating visual analysis when chromatographicaliy, and inorganic binder: highly dispersed silicon dioxide /Aerosil/ or aluminium hydroxide, drying the plate /Patents Germany 1517929, class B 01 D 15/08, 1966/. Introduction fine neorganicheskoi and then adding water to make slurry, or adding to the aqueous suspension of one of the components dry or suspended in water other components. The use of inorganic binder allows you to use the aggressive manifesting mixtures at high temperatures for the manifestation of the chromatograms.

The plate obtained in a known manner, are of high quality, secure good adhesion of the adsorbent to the substrate, which enables long-term storage and transportation of wafers without damage. However, the known plates are designed for single use and after analysis are sent for recycling. Attempts regeneration plates lead to peeling of the adsorbent from the substrate.

A method of obtaining plates for TLC by pre-treatment of aluminium foil sandblasting to obtain a roughness of 0.8 to 1.5 μm, the coating on the thus prepared substrate water dispersion of the adsorbent is silica gel, a binder - silicates with the addition of fine silica and phosphor, drying plates /Patent RF 2037826, CL G 01 N 30 /92/.

The plate obtained in a known manner, have good mechanical strength, they are suitable for detection is about to use /8-10 times/.

However, the known method and the plates have a number of drawbacks. The known method requires energy, special facilities and equipment in the preparation of the substrate: quartz sand with a particle size of 0.3-0.7 mm under the pressure of compressed air 0,06-0,15 MPa is supplied from the nozzles with a diameter of 8-10 mm, set at a distance of 80 to 140 mm from the surface of the substrate, moving with a speed of 0.8-1.4 m/min substrate. Sizing the roughness of the substrate is accompanied by a large error, therefore, poor reproducibility quality plates for mass production. When processing a foil sandblasting the major surface of the substrate, which may have competing effects on the process of separation /alternative to separation of the sorbent/. The uneven treatment sandblasting causes edge effect during chromatography: the increasing speed of eluent on the edge of the plate compared with the velocity in the center and, therefore skewing the results.

Thus, the problem of creating plates for TLC is relevant.

The task of the invention is to develop a technologically advanced way p the m way to get plates for TLC.

The inventive method is described using the following operations:

1. As the substrate using a metal foil

2. Before applying the adsorbent metal foil prepared in a special way.

2.1. The metal foil is treated with 1-8% aqueous solution of liquid glass /aqueous solution of silicates of potassium and sodium/ containing 0.5 to 2.0% of sodium hydroxide or potassium hydroxide, at room temperature.

3. On the prepared substrate is applied, the suspension of the adsorbent and binder.

3.1. As the adsorbent using silica gel, alumina, magnesium silicate, diatomaceous earth.

3.2. As a binder used inorganic binder: silicasol, silicasol with the addition of highly dispersed silicon dioxide, gypsum.

3.3. As an additive in the slurry, introducing the phosphor.

The metal foil can be either aluminum, stainless steel, Nickel bronze, brass, coated with a layer of chromium. If the presentation of chromatograms, the adsorbent can be used polyamide or cellulose powders, ion-exchange resins, and as the binder is starch, polyvinyl alcohol, polyvinylpyrrolidone.

This set of essential features of the claimed method provides the technical result - effective plates for TLC reusable due to the improved adhesion of the adsorbent to the substrate and, consequently, to increase the mechanical strength of the plate. Obtained by the claimed method of the TLC plate can be used after regeneration in hostile environments up to 15-20 times, and in sparing the environment /for example, in an organic solvent / - an unlimited number of times. Additional effect: improving the quality of the chromatograms, no edge effect.

The proposed method is environmentally friendly, energy - saving, easy hardware implementation, more cheap in comparison with the known analogues. Achieved good reproducibility of quality plates.

The hallmark of the proposed method from the prototype method is characteristic 2.1., that is, the original preparation of the metallic foil to the application of the adsorbent.

Analysis of the known prior art did not allow to find a solution that exactly matches the set of essential characteristics of the claimed method.

Inwestowanie liquid glass when receiving plates for TLC. The process of degreasing the surface of a metal foil, for example, using soapy water, as can be seen from the analysis of the analogies, it is not possible in combination with other essential features to get the plates are reusable, adhesion of the adsorbent to the substrate is insufficient to withstand the regeneration plates. The authors of the invention have put special experiments using in preparation of the substrate processing liquid glass. The results were consistent with the counterparts, the effect of the present invention was not obtained.

Known etching the surface of the metals sodium hydroxide solution at 70-90oC. Method of ethnological, as it is performed at high temperature and the etching produces a large quantity of hydrogen. If the authors of the claimed invention, etching of the surface of an aluminium foil with a solution of sodium hydroxide were obtained of the plate, the mechanical strength inferior counterparts.

Sharing water glass and sodium hydroxide, especially in the stated interval parameters and at room temperature, is not known.

The unknown characteristic 2.1 confirms the novelty of the proposal.Could also be assumed that the substrate of the proposed method will have good adhesion to almost all known adsorbent, and not only to the silica gel, as in the case of the prototype method.

Thus, in the present method introduces a new functional dependency operation - property. This suggests accordance of the present invention Ostia solutions to the eligibility condition "industrial applicability" and for a better understanding of the essence of the claimed invention, examples of specific performance.

Thickness was measured using a micrometer, the thickness of the layer of adsorbent was determined as the difference of the thicknesses of the plate and the foil.

Example 1.

Aluminum foil with the thickness of 120 μm, the size of h mm were placed at room temperature in a composition containing 6% aqueous solution of liquid glass with dissolved 1.2% of potassium hydroxide. Kept for 10 minutes the Treated foil was removed from the composition, washed with water, dried.

The treated aluminum foil was applied aqueous suspension of adsorbent consisting of 4 g of silica gel KSK diameter part of 4-8 μm and 10 ml of silicates - stable Sol of silicic acid with a pH of 7 and a concentration of SiO340 mg/ml /4% SiO2/.

The plate was dried as follows: 5 min at 80oC, 20 min at 18oC, 40 min at 120oC.

The plate thickness of 240 μm, a layer of adsorbent - 120 microns.

Example 2.

Analogously to example 1. The composition for treatment of aluminium foil: 1% solution of liquid glass with dissolved 1.2% of potassium hydroxide.

The plate thickness of 240 μm, a layer of adsorbent - 120 microns.

Example 3

Analogously to example 1. The composition for treatment of aluminum foil: 8% solution of liquid glass from rest aluminum foil: 6% solution of liquid glass with dissolved 0.8% of sodium hydroxide.

The plate thickness of 240 μm, a layer of adsorbent - 120 microns.

Example 5.

Analogously to example 1. The composition for treatment of aluminum foil: a 6.5% solution of liquid glass with dissolved therein 0.5% sodium hydroxide.

The plate thickness of 240 μm, a layer of adsorbent - 120 microns.

Example 6.

Analogously to example 1. The composition for treatment of aluminum foil: 6% solution of liquid glass with dissolved in it to 2.0% sodium hydroxide.

The plate thickness of 240 μm, a layer of adsorbent - 120 microns.

Example 7.

Analogously to example 7. In the suspension of the adsorbent includes a phosphor /5% by weight of adsorbent/.

The plate thickness is 240 μm, the layer of adsorbent - 120 microns.

Example 8.

Analogously to example 1, instead of the aluminum used stainless steel foil.

The plate thickness is 240 μm, the layer of adsorbent - 120 microns.

In examples 1 to 5 used glass liquid sodium /soda/ domestic production /31-33% aqueous solution of sodium silicates. The calculation of SiO2/.

In examples 7, 8 used glass soda-sodium sulfate liquid domestic production /28-30% aqueous solution of silicates of sodium and potassium. The calculation of SiO2/e according to examples 1-8 plates for TLC were subjected to tests result found:

1. Received a thin layer of adsorbent is not washed off with water.

2. During curing of each plate in chrome mix /30 sec, 1 min and then washing with water until the pH of the wash water is equal to 7, the layer of adsorbent is not damaged, the communication layer with the substrate is not violated. This process can be carried out without damage to the plates up to 20 times.

2. In parallel with multiple processing chrome mixture was carried out repeated chromatographic separation on the same plate. Achieved full reproducibility of separation when reusing plates /to 20/.

4. When transporting plates do not crack. The shelf life is unlimited.

Quality plates with chromatographic separation:

and/ On the plate for TLC, prepared according to example 1, was applied a mixture of DNS-amino acids. Conducted two-dimensional chromatography in the solvent system: acetone: isopropanol:ammonia /9:7:0.5/, b/ chloroform:benzyl alcohol:ethyl acetate: acetic acid/6:4:5:0.2/. Received a complete separation of amino acids.

After processing the plate chrome with a mixture of experience repeated. Reproducibility full.

Plate handling the tx2">

b/ On the plate for TLC, prepared according to example 2, was applied a mixture of polystyrene standards of the company "Waters" with a molecular mass of 20800, 51100, 98300, 200000, 498000, was chromatographically in the system cyclohexane:toluene:methyl ethyl ketone /17,4:2:1,5/. Obtained complete separation of polystyrene standards.

After washing the plate chrome with a mixture of experience was repeated 15 times. Reproducibility full. Edge effect is missing.

in/ On the plate for TLC, prepared according to example 4, was applied to the mixture of polymer standards "Waters", was suirable in the system cyclohexane:toluene: methyl ethyl ketone /17,4:2:1,5/. Detection: 2%/wt./ a solution of KMnO4in H2SO4conc. and heating to 180oC for 10 minutes

The separated polymer was manifested in the form of dark brown spots on a white background, which is the norm.

The plate was treated with chromic acid mixture. Experiments on the separation was repeated 15 times. The division played. Edge effect is missing.

Experiments and/ b/,/ testify to the high quality of the proposed plates and the possibility of their repeated use in TLC.

The invention is not limited to these examples.

Beyond the stated interval parameters is 8% aqueous solution of liquid glass /1.2% sodium hydroxide/ adhesion deteriorates. By increasing the concentration of the solution of liquid glass to 8.2-8.5 percent increases the viscosity of the solution, it is difficult to wash off. Upon decrease of the concentration of the hydroxides of sodium or potassium to 0.2% get low-quality plates, increasing to 2.2% observed active hydrogen evolution during processing of the foil.

The method of producing plates for thin-layer chromatography, comprising pre-processing the metal foil, the application of a suspension of the adsorbent with a binder, drying the plate, characterized in that the metal foil is treated with 1 - 8% aqueous solution of water glass containing 0.5 to 2.0% of sodium hydroxide or potassium hydroxide at room temperature.

 

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