RU2272284C1 - Indicator sensitive material for determining micro-amounts of substances - Google Patents

Abstract

FIELD: analytical chemistry, possible use for operative control over concentration of admixtures in liquids and gases both under laboratory and field conditions.

SUBSTANCE: in indicating sensitive material hard polymer carrier is made of transparent polymer material containing functional groups, providing inter-molecular interactions with reagent and/or determined substance. Functional groups are selected from row: amide - CONH₂, carboxyl - COOH, hydroxyl - OH, nitrile - CN, complex ether - COO, carbonyl - >C=Output, ether -O-, sulfur -containing -SH, -S-,-S=C,-SO₃H, -SCN, halogen-containing -CF₃, -F, -Cl, -I, organic and non-organic salt-like - (alkyl)acrylates of metals, carboxylates of metals.

EFFECT: indicator sensitive material is simple to manufacture, is capable of reacting to broad range of analyzed substances, and also makes it possible to determine analyzed substances with increased precision at level of maximal allowed and dangerous concentrations in laboratory practice and field conditions in different objects with simplified visual and photo-metric estimate.

1 cl, 10 ex, 3 tbl

Description

The invention relates to analytical chemistry and can be used for operational control of the concentration of impurities in liquids and gases both in laboratory and in the field.

In analytical chemistry, spectrophotometric methods in the ultraviolet and visible regions are widely used to determine metal ions. There are many complexing agents that give colored complexes with metal ions. Known optical chemical sensors for detecting metal ions (Cattrall Robert V. Chemical sensors. - M .: Scientific world, 2000 - p. 87), which are a transparent solid polyvinyl chloride carrier (matrix) into which the analytical reagent is immobilized. Such sensors can only be used in laboratory conditions using a spectrophotometer. In addition, when immobilizing the reagent into the matrix, it must be converted into a lipophilic form. This leads to an increase in reagent consumption and complicates the manufacture of indicator sensitive material.

Sensitive sensitive powder materials are also known, which are used in the form of tablets or in indicator tubes to determine metal ions, anions, organic compounds in liquids. Indicator sensitive material is an opaque powder with a reagent on its surface (Yu.A. Zolotov. The simplest means of analytical control // Chem. Prom., 1997, No. 6 - p. 48-56). The detection of colored compounds is carried out visually. The presence and quantity of the analyzed component is judged by the intensity of the color of the tablet by comparison with a reference scale. For the analytical signal for the indicator tubes take the length of the colored zone of the powder after its contact with the analyzed liquid. For a more accurate analysis, depending on the concentration of the component to be determined, it is advisable to use tubes with different diameters - for low concentrations of about 1 mm, for high concentrations - 2-2.5 mm. In instrumental detection, the opacity of the powders necessitates measuring the amount of light reflected by the tablet, which reduces the accuracy of the analysis. In addition, special containers are needed to store indicator tubes.

For rapid testing of components, an indicator sensitive material based on polyurethane foam is used in the form of an opaque white tablet with a reagent immobilized in its volume. Detection of colored compounds can be carried out visually or using special instruments that record changes in the spectral characteristics of the sensitive element after sorption and the formation of a colored compound (Soros Educational Journal No. 8, 1998, p. 68). The complete opacity of the matrix causes the use of reflective spectroscopy, which leads, as in the previous case, to a decrease in the accuracy of measurements. During visual inspection, the presence of a component is judged by the tone of the color that appears, and the quantity is judged by its intensity after comparison with the reference scale, which allows only a semi-quantitative result, the error of which can be up to thirty percent.

Sensitive indicator material (HMI) for rapid testing of traces of substances (RF patent No. 2067297, IPC 6 G 01 N 31/22, G 01 N 27/416), selected as a prototype, includes a solid carrier, reagent and bleach in the form of manufactured the biofore industry to increase contrast, which leads to an increase in the sensitivity of visual testing. Polymeric fibrous materials with elementary units of cellulose or polyamide are used as a solid support, and a reagent with high selectivity with respect to the ion being determined is used as a reagent. The disadvantage of this HMI is the need to use reagents for which ε _MR / ε _HR ≥1000, where ε _HR is the molar absorption coefficient of the reagent, ε _MR is the molar absorption coefficient of the reagent complex with the determined component. A decrease in this ratio leads to a significant decrease in sensitivity in the region of low concentrations (GD Brykina et al. Solid-phase spectrophotometry. ZhAH, 1995, volume 50, No. 5, p. 484). In addition, the prototype has a complex and multi-stage technology for producing HMI, due to the fact that the solid carrier is treated with a solution of Belofor under slow boiling and stirring for 5-10 minutes, then washed with distilled water and dried for storage or immediately treated with a reagent solution. The actual analysis is carried out in a dynamic mode when the analyzed fluid is passed through a nozzle with an HMI placed at a speed of 30 ml / min.

The objective of the invention is the creation of a transparent indicator sensitive material, which allows to simplify the visual and photometric assessment of changes in its color after contact with the analyzed object.

The problem is solved in that the proposed HMI for determining the components in the analyzed objects, including, like the prototype, a solid polymer carrier with a reagent, according to the invention, a solid polymer carrier is made of a transparent polymer material containing functional groups that provide intermolecular interactions with the reagent and / or determined by the substance and selected from the group of amide -CONH _2, -COOH carboxyl, hydroxyl -OH, nitrile -CN, -COO- ester, carbonyl> C = O, -O- ether, gray won -SH, -S-, -S = C, -SO ₃ H, -SCN, a halogen -CF _3, -F, -Cl, -I, organic and inorganic salt-like - (alkyl) metal acrylates, metal carboxylates.

It is preferable to use polyesters as a solid polymer carrier, for example, [-O-R-O-CO-] _n polycarbonates containing carbonyl functional groups> C = O.

It is reasonable to use polyvinyl esters, for example, polyvinyl acetate [-CH ₂ -CH (OCOCH ₃ ) -] _n , containing ester functional groups -COO as a solid polymer carrier.

Advantageously as the solid carrier polymer used polyalkylacrylates [-CH ₂ -CR (COOR ') -] _n, or copolymers thereof with (alk) acrylic acid _CH2 = CR (COOH) or salts of (alkyl) acrylic acid (CH ₂ = CR (COO)) _n Me, for example, (meth) metal acrylates containing carboxyl-COOH, ester-COO functional groups as well as metal carboxylates (CH ₂ = CR (COO)) _n Me.

It is reasonable to use polyacrylonitrile [—CH ₂ —CH (CN) -] _n or its copolymers with (alkyl) acrylate CH ₂ = CR (COOR '), styrene CH ₂ = CH (C ₆ H ₅ ) containing solid polymer support composed of nitrile -CN, ester -COO functional groups.

Preferably, the polyacrylamides [—CH ₂ —CH (CONH ₂ ) -] _n and / or their copolymers with (alkyl) acrylate CH ₂ = CR (COOR ′) and / or acrylonitrile CH ₂ = CH (CN ), and / or styrene CH ₂ = CH (C ₆ H ₅ ) containing amide —CONH ₂ , nitrile —CN functional groups.

To obtain a transparent HMI by radical block polymerization, mixtures of monomers and substances containing the above-mentioned functional groups were used. The necessary form is attached to the solid polymer carrier through the use of the corresponding polymerization form or, after polymerization, by thermal pressing. In the first case, the polymer material, as a rule, is formed in the form of thin plates of large area, which are subsequently cut into plates of the desired size.

In addition, to obtain a transparent HMI, ready-made transparent polymers are used, which are dissolved in a solvent with a reagent and substances containing the above-mentioned functional groups. The mixture is stirred until a homogeneous mass is obtained, after which a viscous solution is poured into a mold or on a plane-parallel surface of a material with poor adhesive properties, for example, on a fluoroplastic substrate, and the resulting thick film is dried. If necessary, the latter is cut into plates (films) of the desired size.

Functional groups providing intermolecular interactions are contained both in units of optically transparent polymers and are additionally introduced, more preferably at the stage of formation of the polymer carrier.

The formed indicator material, if necessary, is sealed in polyethylene; the latter is mandatory if substances sensitive to oxygen and moisture are used as reagents.

Further, the invention is illustrated by examples.

Example 1. A transparent polymer material with polymethyl methacrylate units — a copolymer of methyl methacrylate with methacrylate, obtained by radical polymerization in plane-parallel form, is cut out in the form of rectangular plates with an area of 1 cm ² and a thickness of 0.1 cm. To obtain indicator material for iron ions (II, III ) the carrier plate is treated for 5 minutes with a 0.5% solution of the reagent (2,2'-dipyridyl or 1,10-phenanthroline) in acetic acid buffer with a pH of 4.7. To determine the content of Fe (II, III), the obtained sensitive indicator material is placed in 50 ml of the analyzed solution containing 1 ml of a 1% solution of ascorbic acid or hydroxylamine hydrochloride to restore Fe (III) in Fe (II), mixed (by shaking or stirrer) in within 20-30 minutes. After that, the plates are dried between sheets of filter paper and the determination of iron is carried out by:

- measuring the optical density of the plates at a wavelength of 510 nm; the concentration of iron ions is determined by pre-constructed calibration graphs (the dependence of optical density on the concentration of the element being determined). The detection limit (PrO) is 0.01 mg / L.

Another way to find the iron content is visual - by comparing the color intensity with a previously constructed scale in the range of determined concentrations (the detection limit in this case is 0.04 mg / l). The results are shown in table 1.

The use of other solid polymer carriers from the series of (alkyl) acrylates and their copolymers for the formation of the HMI provides similar results. The main results are summarized in table 1.

Example 2. A transparent polymeric material — a polymeric material with polymethyl methacrylate units — a copolymer of methyl methacrylate with styrene obtained by radical polymerization followed by thermal pressing in the form of rectangular plates with an area of 1 cm ² and a thickness of 0.05 cm. To obtain indicator material for ascorbic acid (vitamin C ) the plate is treated with a 0.5% solution of the reagent (2,2'-dipyridyl or 1,10-phenanthroline) in acetate buffer for 5 minutes, then with a solution of Fe (III) at a concentration of 0.3 mg / L. The resulting indicator material is placed in 50 ml of the analyzed solution and shaken for 30 minutes. After contact with the analyzed solution, the plates are dried between filter paper. The determination of the content of ascorbic acid in the analyzed solution is carried out analogously to example 1. The results are shown in table 1.

Example 3. A transparent polymeric material - a copolymer of acrylamide with (meth) acrylate, obtained by radical polymerization in a flat form, cut out in the form of rectangular plates with an area of 1 cm ² and a thickness of 0.1 cm. To obtain a sensitive indicator material for mercury (II) is introduced into a copper dithizonate carrier, treating it with a solution of dithizone in carbon tetrachloride, then with a solution of copper sulfate for 0.5 min. The resulting indicator material is placed in 100 ml of the analyzed solution, the latter adjusted to pH 1-2, shaken for 30 minutes. After contact with the analyzed solution, the plates are dried between sheets of filter paper. Determination of the content of Hg (II) in the analyzed solution is carried out by instrumental and visual methods:

1) remove the optical density of the plates at a wavelength of 490 nm, the concentration of mercury (II) is determined by pre-constructed calibration graphs (the dependence of optical density on the concentration of the element being determined);

2) the color change of the sensitive indicator material is compared visually with a previously constructed scale in the range of determined concentrations from the content of Hg (II) equal to 0.02 mg / L.

The results are shown in table 1.

In addition, table 1 shows the results of examples 4-9.

Example 10. Indicator sensitive material in the amount of heavy metals.

A portion of 1- (2-pyridylazo) naphthol (0.01 g) is dissolved in a few drops of ethyl alcohol. 0.2 g of propylene carbonate and polyethylene glycol, 3 ml of a mixture of methylene chloride with dichloroethane (1: 1) are added. The mixture is mixed until a homogeneous mass is obtained, after which the solution is poured onto a fluoroplastic substrate. The applied film (layer) is dried in air or in a thermostat chamber at 40 ° C. The obtained indicator sensitive material is placed in 50 ml of a solution containing 0.002-0.05 mg of heavy metals (Zn, Cd, Pb, Cu) and stirred for 20-30 minutes. After contact with the analyzed solution, the HMI is dried between filter paper. The determination of the total content of heavy metals in the analyzed solution is carried out in two ways:

1) remove the optical density of the film at a wavelength of 560 nm, the concentration of the sum of heavy metals is determined by pre-constructed calibration graphs (dependence of optical density on the concentration of the element being determined);

2) compare the color change with a previously constructed scale in the range of determined concentrations.

The measurement results are shown in table 2. In addition, table 2 shows the results of example 7.

Table 3 shows examples of the determination of trace amounts of iron and ascorbic acid in various objects.

Thus, the claimed HMI is simple to manufacture and is able to respond to a wide range of analytes; the range of the latter is determined by the tasks of analysis. The proposed HMI allows you to determine the analytes with increased accuracy at the level of maximum permissible and dangerous concentrations in laboratory practice and field conditions in various objects.

Table 2.
Indicator sensitive materials obtained by forming a film (layer) from a solution No. Polymer material Component to be defined Pro, mg / l Reagent (color) Complex color Instrumental detection Visual detection one polyesters, for example polycarbonates [-ORO-CO-] _n . Σ heavy metals 0.005 0.005 1- (2-pyridylazo-2-naphthol) (orange) raspberry violet 2 polyvinyl esters, for example polyvinyl acetate [-CH ₂ —CH (OCOCH ₃ ) -] _n . Zn 0.005 0.005 1- (2-pyridylazo-2-naphthol) (orange) crimson

Table 3.
Examples of use of indicator sensitive material No. p / p Analyzed object Component to be defined Found (Sr) Instrumental method Visual method Mineral water one "Birch" Fe (II, III) 0.05 ± 0.03, mg / L (0.01) 0.04 ± 0.02, mg / L (0.01) Chazhemto 0.07 ± 0.02, mg / L (0.007) 0.05 ± 0.01, mg / L (0.01) Orange juice "J7" 0.023 ± 0.004,% (0.003) 0.03 ± 0.01,% (0.05) 2 "My family" Vitamin C 0.016 ± 0.003% (0.003) 0.015 ± 0.005% (0.04) "I AM" 0.006 ± 0.003% (0.003) 0.008 ± 0.001% (0.01) "Tone" 0.024 ± 0.001,% (0.001) 0.03 ± 0.01,% (0.01)

Claims (7)

1. Indicator sensitive material for determining the micro amounts of substances in the analyzed objects, including a solid polymer carrier with a reagent, characterized in that the solid polymer carrier is made of a transparent polymer material containing functional groups that provide intermolecular interactions with the reagent and / or the substance being determined and selected from series: amide —CONH ₂ , carboxylic —COOH, hydroxyl —OH, nitrile —CN, ester —COO—, carbonyl> C = O, ether —O—, sulfur-containing —SH, —S—, —S = C, - SO ₃ H, -SCN, halogen-containing-CF ₃ , -F, -Cl, -I, organic and inorganic salt-like - (alkyl) metal acrylates, metal carboxylates. 2. The indicator sensitive material according to claim 1, characterized in that polyesters, for example, polycarbonates [-O-R-O-CO-] _{n, are} used as a solid polymer carrier. 3. The indicator sensitive material according to claim 1, characterized in that polyvinyl esters, for example, polyvinyl acetate [-CH ₂ CH (OCOCH ₃ ) -] _{n, are} used as a solid polymer carrier. 4. The indicator sensitive material according to claim 1, characterized in that the polymeric alkyl acrylates [—CH ₂ —CR (COOR ′) -] _n or their copolymers with (alkyl) acrylic acid are used as a solid polymer carrier. 5. The indicator sensitive material according to claim 1, characterized in that copolymers of polyalkyl acrylate with salts of (alkyl) acrylic acid are used as a solid polymer carrier. 6. The indicator sensitive material according to claim 1, characterized in that polyacrylonitrile [—CH ₂ —CH (CN) -] _n or its copolymers with (alkyl) acrylate, styrene are used as a solid polymer carrier. 7. The indicator sensitive material according to claim 1, characterized in that the polyacrylamides [—CH ₂ —CH (CONH ₂ ) -] _n and / or their copolymers with (alkyl) acrylate and / or acrylonitrile are used as a solid polymer carrier; and / or styrene.