RU2284520C1 - Reagent indicating paper for determining aluminum - Google Patents

Abstract

FIELD: investigating or analyzing materials.

SUBSTANCE: paper comprises paper matrix that contains organic reagent made of aluminon. The paper matrix is made of cellulose modified by epichlorohydrin. The organic reagent is made of a composition of adsorbed aluminon with covalently immobilized aluminon. The cellulose modified by epichlorohydrin is related to adsorbed aluminon and is related to covalently immobilized aluminon as (500-1000):(5-9):1, in mass.

EFFECT: enhanced reliability of determining.

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Description

The invention relates to analyzers of non-biological materials using chemical indicators, in particular, to indicator means for the rapid determination of trace amounts of aluminum (III).

Known test tools for the determination of aluminum (III): indicator tubes and indicator papers with immobilized organic reagents [V. M. Ostrovskaya, O. A. Zaporozhets, G. K. Budnikov, N. M. Chernavskaya. Water. Indicator systems. M., FSUE VTPI, 2002, pp. 40-42, 79, 82]. The main disadvantages of these test tools are not very high sensitivity and the inability to determine aluminum on the surface of metal products.

Reagent indicator papers (RIB), which are not distinguished by selectivity and sensitivity, are currently used to determine aluminum. Known papers of the company "Carlo Erba" for the determination of aluminum in the concentration range of 500-300 mg / l, as well as indicator strips (IP) of the company "Merck" for the determination of aluminum in the concentration range of 5-500 mg / l, and the concentration is determined by the color intensity after contact of the paper with the test liquid [Merckoquants-Tests. Teststabchen zur halbquantitativen Bestimmung von lonen und Verbindungen, Merck. Darmstadt. S.96].

The most sensitive is the RIB for determination of aluminum, which is paper impregnated sequentially with a 2 × 10 ^-4 M solution of thiazolylazopyrocatechol, and then with a 4 × 10 ^-4 M solution of cetylpyridinium and, thus, containing an associate of these reagents, respectively, in a 1: 2 ratio. RIB has a yellow color, and with aluminum gives a red color. PI, glued into a polymer film, is suitable for determining the concentration of aluminum in the region of 1-50 mg / ml, which is estimated by the length of the colored zone, and PI with a device for concentration in the range of 0.01-0.5 mg / l - by color formed after pumping 20 ml of the solution [Amelin V.G., Ivanov V.M. Test analysis method using paper-immobilized associates of pyrocatechol azo derivatives, trioxifluorones with cetylpyridinium and their chelates with metal ions // Journal of Analytical Chemistry, 2000, V. 55, No. 4. S.411-418.].

The main disadvantages of this indicator paper is the limited sensitivity with a low visual contrast of the color transition in contact with the analyzed solution containing aluminum. In addition, these PIs are unsuitable for determining aluminum on the surface of metal products, as in composition due to the fact that the analyzed surface may be contaminated with cetylpyridinium chloride, i.e. it is impossible to avoid contamination with reagents controlled in terms of cleanliness of particularly clean objects, and in form due to the fact that it is structurally impossible to produce an IP form suitable for contact with the surface.

The closest in technical essence and taken as a prototype is the indicator strip of the company "Merck" for the determination of aluminum (III), including a paper matrix containing aluminone [Merckoquants-Tests. Teststabchen zur halbquantitativen Bestimmung von lonen und Verbindungen, Merck. Darmstadt. S.96]. The disadvantage of this PI is the low sensitivity of 10 mg / l, which is due to the easy leachability of aluminone from the cellulose base.

The present invention is directed to the creation of reagent indicator paper for the determination of aluminum (III), which has high sensitivity, high contrast color transition when interacting with aluminum (III), resistance to erosion, and also allows you to use it for the manufacture of various forms of PI, suitable for test determination of aluminum in a wide range of volumes of liquid samples and concentrations of 0.005-50 mg / l, as well as suitable for determining aluminum (III) on a metal surface and for determining traces of corr sion aluminum containers for storage of aggressive liquids.

The technical result of the invention is to increase the sensitivity of testing indications while reducing the leachability of the indicator from the cellulose base and expanding the range of analyzed samples.

The technical result is achieved by the fact that the proposed reagent indicator paper for determining aluminum, consisting of a paper matrix containing an organic reagent aluminon; according to the invention, epichlorohydrin modified cellulose is used as a paper matrix, and a composition of adsorbed aluminone with covalently immobilized aluminone is used as an organic reagent in the following weight ratios: epichlorohydrin modified cellulose: adsorbed aluminone: covalently immobilized aluminone (500-1000) :( 9): 1.

At ratios adsorbed aluminon: covalently fixed aluminin less than 5: 1, the color of the paper becomes less intense, and at ratios greater than 9: 1 the paper is partially washed out and contaminates the object under study with an excess of reagent.

Resistance to erosion is determined by the absence of staining of the sample and the uniformity of color of the indicator zone of the RIB.

Figure 1. The histogram is the reflectometric characteristic of the RIB: the dependence of the R ₀ / R _i index on the wavelength of the maximum radiation of the LED, where R ₀ and R _i are the reflection coefficients of the pure RIB and the product of the interaction of the RIB with aluminum, respectively, measured on an ECOTEST-RTG reflectometer (certificate No. 20328) of the company "ECONIX".

Figure 2. The intensity of the color change of the RIB at different concentrations of the impregnating solution of aluminon: 0.1% (1), 0.2% (2), 0.3% (3) and a fixing temperature of 80 ° C. Reflectometric indices R ₀ and R _{i were} measured on a MULTIEKOTEST colorimeter-reflectometer of KOSTIP firm KNZHG 414212.001 PS. LED 565 nm.

Figure 3. The color intensity of the RIB at different concentrations of the impregnating solution of aluminon: 0.1% (1), 0.2% (2), 0.3% (3) and a fixing temperature of 90 ° C. LED 565 nm.

Figure 4. The color intensity of the RIB at different concentrations of the impregnating solution of aluminin: 0.1% (1), 0.2% (2), 0.3% (3) and a fixing temperature of 100 ° C. LED 565 nm.

Figure 5. The color intensity of the RIB at different concentrations of the aluminone impregnating solution: 0.1% (1), 0.2% (2), 0.3% (3) and a fixing temperature of 110 ° C. LED 565 nm.

6. Calibration graphs for the determination of aluminum (III) at different impregnating concentrations of alumininone while passing 3 ml of solution. OTKET-RTG reflectometer. 525 nm LED

7. Calibration schedule for determination of aluminum (III) when passing 20 ml of solution. LED 525 nm.

Rib is made as follows. Base paper for rapid tests with a specific surface area of 80 g / m ² (for RIB I) or 160 g / m ² (for RIB II) according to TU 13-730800-721-85, containing 95% α-cellulose, is impregnated sequentially With a 12% aqueous solution of caustic soda, the solvent is removed and the resulting paper in the form of sodium cellulose is poured with epichlorohydrin to which 15-crown-5 phase transfer catalyst is added. After a day, the paper is separated from epichlorohydrin, dried and impregnated with a 0.1-0.3% solution of aluminone (triammonium salt of auritricarboxylic acid), dried at a temperature of 80-110 ° C. At temperatures less than 80 ° C, covalent bonding of aluminon occurs slowly and the color intensity of the RIB is less. At a temperature of more than 110 ° С, alumininone color changes and the complex color intensity also decreases. RIB has a light pink or white with a yellow tint color and forms a reaction product of red color when interacting with aluminum (III). Moreover, the highest contrast and color transition intensity are observed with green LEDs with a maximum light emission at 500-565 nm. The obtained RIBs allow the manufacture of the following strip shapes: 1) from RIB I — indicator strips measuring 9.8 × 30-50 mm (test form 1, RIB-Aluminum-Test); 2) from RIB I — squares of 10 × 10 mm in size, sealed together with a clean strip of paper in a polymer film (test form 2); 3) from RIB II — squares of 10 × 10 mm in size, attached with double-sided adhesive tape at the end of a 10 mm wide polymer strip substrate (test form 3, RIB-Aluminum-Test II).

The optimal concentration for impregnating RIB I is 0.1-0.15 wt.% Aluminone, and for RIB II 0.2-0.3 wt.% Aluminone, in which the reaction product of RIB I with aluminum has the highest optical density and higher ratios reflection R ₀ / R _i , where R ₀ and R _i are the reflection coefficients of pure RIB and its complex with aluminum (tables 1 and 2, FIGS. 2-5). Used standard aluminum solutions according to GOST 4212-82.

Table 1 shows the concentration of impregnating solutions of aluminone at a temperature of 95 ° C. Table 2 shows the fixing temperature and concentration of the impregnating solutions of aluminin at different temperatures. As you can see, the best was for the brand III base paper (160 g / m ² ), test form 3, RIB-Aluminum-Test II, curing temperature 100-105 ° C at a concentration of an impregnating solution of 0.3% aluminone in water-alcohol solution (vol. 80:20), and for thinner base paper of brand I (80 g / m ² ), test form 1, RIB-Aluminum-Test - 0.15% aluminone in the same aqueous-alcoholic solution at fixing temperature 95-100 ° С; fixing time in both cases (optimal) - 5 minutes.

Table 1
The choice of the optimal concentration of the impregnating solution to obtain from RIB I (80 g / m ² ) test form 1 (RIB-Aluminum-Test) and test form 2.
The sample volume of a standard solution of Al (III) 3 ml. No. % aluminone in solution R ₀ / R _i * 0.3 mg / L Al (III) R ₀ / R _i * 1 mg / l Al (III) Ratio** 0 0 one one one 0.01 1.19 1.29 2.6 2 0.02 1.39 1.49 3.6 3 0.05 1,54 1.66 4.3 four 0.08 1.55 1.70 4.7 5 0.1 1.80 1.96 5,4 6 0.15 1.74 2.42 7.1 7 0.2 1.70 2,53 7.8 8 0.3 1.68 2.25 9.8 9 0.4 1.55 2.20 11.9 10 0.5 1.45 2.25 13.1 eleven 1,0 1,11 1.98 17.6 12 2.0 1.09 1.23 29.5 * R ₀ / R _i is the indicator, where R ₀ and R _i are the reflection coefficients of the pure RIB and the product of the interaction of the RIB with aluminum (III), respectively, measured at 525 nm on an ECOTEST-RTG reflectometer (certificate No. 20328) of ECONIX ".
** Ratio - adsorbed aluminon: covalently immobilized aluminon table 2
The dependence of the color intensity of the test form II (RIB-Aluminum-Test II) from RIB II (160 g / m ² ) with aluminum on the conditions for the fixation of aluminon: its concentration (C) and temperature (T). T, ° С FROM, % Background, mg / L Color intensity R ₀ / R _i * at Al concentration, mg / L 0 0.1 0.3 one 3 501 80 0.1 one 1.12 1.48 1.55 1.83 1.70 0.2 one 1.28 1.44 1.85 2.28 2.45 0.3 one 1.18 1.74 2.07 2.84 3.05 90 0.1 one 1,11 1.26 1.74 1.90 1.81 0.2 one 1.22 1.38 2.16 2.68 2.16 0.3 one 1.09 1,63 2.11 2.48 2.85 one hundred 0.1 one 1.25 1.36 1.60 1.82 1.92 0.2 one 1.25 1.65 1.93 2,33 2.70 0.3 one 1.27 1,56 2,32 2.93 3.24 110 0.1 one 1.15 1.44 1,57 1,67 1.83 0.2 one 1.12 1,56 1.73 2,37 2.13 0.3 one 1.26 1.89 2,37 3.03 2.69 R ₀ and R _i are the reflection coefficients of the pure RIB and the product of the interaction of the RIB with aluminum (III), respectively, measured at 565 nm on a MULTIEKOTEST colorimeter reflectometer from KOSTIP firm KNZHG 414212.001 PS.

Below are examples of the use of the claimed RIB.

Example 1. Determination of aluminum (III) in diluted standard solutions (GOST 4212-82) and the construction of a color scale.

PI (test form 1) at one end is placed in a pocket pumping device [Ostrovskaya V.M. A device for determining the trace amounts of substances. Pat. RF 2095779, 1997. Bull. No. 31] and pass 20 ml of the sample, get a natural color scale in the range of aluminum (III) concentrations of 0.003-0.01-0.03-0.1-0.3 mg / l, and when passing 3 ml of solution in the range aluminum (III) concentrations of 0.05-0.15-0.5-1-3 mg / l.

PI (test form 2) is immersed at one end with a square RIB in the solution and after absorbing the liquid to the upper second end of the strip, the color of the colored zone is determined in the range of aluminum (III) concentrations of 0.3-1-3-10-20 mg / l.

PI (test form 3) is immersed at one end in the sample for 1 second and a scale is obtained in the concentration range of 2-5-10-20-50 mg / l.

Color transitions are recorded using standard printing color grading scales TU 29.01-91-83 of the ECOTEST comparator, table 3, concentration scales (KSh) 1-5 for five concentration ranges or a reflectometer with a green LED 525 nm (Fig.6, 7), and also for surface concentration (KS 5).

Table 3
Color and concentration scales of the ECOTEST comparator Composition of printing ink,% and the procedure for applying them Test form Sample volume No. KSh * The ranges of aluminum concentrations, mg / l (for KSh 1-4), μg / cm ² (for KSh 5) one 20 ml one 0 0.003 0.01 0,03 0.1 0.2 one 3 ml 2 0 0.05 0.15 0.5 one 3 2 0.1 ml 3 0 0.3 one 3 10 twenty 3 0.05 ml four 0 2 5 10 twenty fifty 3 0.05 ml 5 0 0.1 0.3 one 3 10 Blue 0 0 0 0 0 0 Purple 10 twenty thirty fifty 60 80 Yellow 0 0 0 10 10 twenty Black 0 0 0 10 10 10 * KSh - concentration scale

Example 2. Determination of aluminum in drinking water.

The RIB strip (test form 1) is placed in a pocket pumping device and 20 ml of solution is passed through the RIB indicator zone, the color transition through the comparator from light pink to red is observed (table 3, KSh 1). The sensitivity is 0.003 mg / L.

Example 3. Determination of aluminum in solutions.

RIB (test form 1) is brought into contact with aqueous solutions by immersion in a solution with a content of more than 2 mg / l (table 3, KS 4) or passed through RIB of 3 ml (table 3, KS 2) or 20 ml (table 3, KSH 1) samples at a lower concentration and determine the aluminum content by the color of the indicator zone by the comparator (table 3), or place in the reflectometer cell and determine the calibration graphs (6, 7). The sensitivity is 0.003 mg / l of aluminum; the contrast of the color transition allows to determine the concentration in the range from 0.003 to 50 mg / L.

Example 4. Determination of aluminum (III) on the surface.

On a PI (test form 3), 1 drop of water or an acetate buffer solution with a pH of 3-5 is applied and pressed to the metal surface with an indicator square down. The contrast of the color change of the test form allows you to determine the aluminum content (III) in the concentration range of 0.1-0.3-1-3-10 μg / cm ² , which corresponds to the color transitions of the comparator (table 3, KSh 5).

Thus, the proposed reagent indicator paper in the form of various test forms based on it allows the rapid determination of aluminum (III) in an aqueous medium in the concentration range of 0.005-50 mg / l and on a metal surface in the concentration range of 0.1-5 μg / cm ² . All types of test forms are resistant to erosion.

Claims (1)

Reagent indicator paper for the determination of aluminum, consisting of a paper matrix containing the organic aluminon reagent, characterized in that the cell matrix is cellulose modified with epichlorohydrin, and the composition of adsorbed aluminone with covalently immobilized aluminone is used as the organic reagent in the following weight ratios: modified epichlorohydrin cellulose: adsorbed aluminon: covalently immobilized aluminon (500 ÷ 1000) :( 5 ÷ 9): 1.

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