RU2078333C1 - Method of analysis of aromatic hydroxiderivatives - Google Patents

Abstract

FIELD: photometric analysis of aromatic hydroxiderivatives in natural water and sewage. SUBSTANCE: method includes treatment of analyzed solution at pH from 9.0 to 12.0 with tetrafluoroborate of 4-nitrophenyldiasonium up to concentration 0.01-0.03 M and with cation surface-active substances up to concentration $$$ M, sorption of formed colored nitrocompound on polyurethane and measurement of diffuse reflection. EFFECT: improved authenticity of method. 6 tbl

Description

 The invention relates to analytical chemistry (photometric analysis) and can be used for photometric determination of aromatic hydroxy derivatives in natural and waste waters.

A known method for determining aromatic hydroxy derivatives, including processing the analyzed solution at pH 8-10 with a 0.1% solution of tetrafluoroborate 4-nitrophenyl diazonium containing 100 ml ≈ 2 ml of 40% HBF ₄ and subsequent measurement of the optical density of the colored solution [1] The method is characterized by low sensitivity.

The closest to the sensitive technical essence and the achieved result is a method for determining aromatic hydroxy derivatives, including processing the analyzed solution at pH 10.3 ± 0.1 with 4-nitrophenyl diazonium tetrafluoroborate to a concentration of 6.3 • 10 ^-5 M, adding hydrochloric acid to pH 3 6 ± 0.3, sorption of the resulting azo compound on an UPM-55 ultrafiltration membrane by filtering the solution at a pressure of 0.5 MPa, desorption of the azo compound by washing the membrane twice with acetone, filtering with acetone solution and its chromatographic analysis with photometric detection [2]
The method is time-consuming, since the conditions for the formation of a colored azo compound and its sorption differ from each other, which makes it necessary to introduce an additional stage of processing the solution with hydrochloric acid before sorption. In addition, in the method it is necessary to maintain the pH with high accuracy both at the stage of formation of the azo compound and its sorption. Sorption of the azo compound is carried out at a pressure of 0.5 MPa and for the analysis, the azo compound is desorbed and the resulting solution is filtered, which also complicates the method.

A method is proposed that eliminates these disadvantages. The proposed method for the determination of aromatic hydroxy derivatives involves processing the analyzed solution at a pH of 9 to 12 with 4-nitrophenyl diazonium tetrafluoroborate to a concentration of 0.01 0.03 M, cationic surfactants to a concentration of 8 • 10 ^-5 - 2 • 10 ^-4 M, sorption the resulting colored azo compound on polyurethane foam and a change in diffuse reflection.

Distinctive features of the proposed method are the treatment of the analyzed solution with a reagent to a concentration of 0.01 0.03 M, the addition of cationic surfactants to the resulting solution to a concentration of 8 • 10 ^-5 2 • 10 ^-4 M, sorption of the already colored compound on polyurethane foam and measurement diffuse reflection.

We found that processing the analyzed solution with a reagent to a concentration of 0.01 0.03 M, adding cationic surfactants to the resulting solution to a concentration of 8 • 10 ^-5 - 2 • 10 ^-4 M, sorption of the colored compound on polyurethane foam and measuring diffuse reflection allows you to simplify the method, since the conditions for the formation of a colored azo compound and its sorption do not differ from each other, and these processes occur in a wide range of pH values; sorption of the azo compound is carried out at atmospheric pressure and there are no additional desorption and filtration operations. When the concentration of the reagent is less than 0.01 M or more than 0.03 M, the degree of extraction of the azo compound decreases, which leads to a decrease in the sensitivity of determination of aromatic hydroxy derivatives. When the concentration of cationic surfactants is less than 8 • 10 ^-5 M or large 2 • 10 ^-4 M, the degree of extraction of the azo compound decreases, which leads to a decrease in the sensitivity of determination of aromatic hydroxy derivatives.

 Example 1

10 μg of phenol, 3 ml of 0.1 M 4-nitrophenyl diazonium tetrafluoroborate, 5 ml of 10% Na ₂ CO ₃ , cetyltrimethylammonium bromide to a concentration of 1.3 • 10 ^-4 M are added to a vessel with a ground stopper to a total volume of 25 ml Polyurethane foam of brand 5 30 is placed in a vessel in the form of a tablet with a diameter of 16 mm and a height of 8 mm, the vessel is shaken on a mechanical vibrator, the tablet is taken out, dried with filter paper and diffuse reflection R is measured.

 Example 2

 In the conditions of example 1, polyurethane foams of brands 140, M-40, 2200, frost-resistant, breathable are used.

 Example 3

 Under the conditions of Examples 1 and 2, decyl, dodecyl, tetradecyl trimethylammonium, cetyl pyridinium and dodecyl pyridinium bromides are used.

 Example 4

Under the conditions of Example 1, a calibration curve is constructed in the coordinates (1 R) ² / 2R of the phenol content, μg / ml (in solution) or μg (on the sorbent), the detection limit is calculated and the lower and upper boundaries of the determined phenol contents are found.

 The relative detection limit of phenol is 0.003 μg / ml, the absolute - 0.07 μg. The lower limit of the determined phenol contents is 0.01 μg / ml and 0.25 μg, the upper 0.80 μg / ml and 20 μg.

 Data on the relative and absolute detection limits of phenol at other concentrations of tetrafluoroborate 4-nitrophenyl diazonium and cetyltrimethylammonium bromide are given in table. 1 and 2, respectively.

 Example 5

 Under the conditions of Examples 1 and 4, brand 140 polyurethane foam was used. The relative detection limit was 0.001 μg / ml.

The relative detection limits when using polyurethane foam grades M-40, 2200, breathable, frost-resistant are respectively 0.005, 0.01, 0.009, 0.02. The metrological characteristics given above do not change in the concentration range of 4-nitrophenyl-diazonium tetrafluoroborate from 0.01 to 0.03 M and cetyltrimethylammonium bromide from 8 • 10 ^-5 to 2 • 10 ^-4 M.

 Example 6

 Under the conditions of Examples 1 and 4, water was added to a total volume of 100 ml. The relative detection limit of phenol is 0.002 μg / ml.

 Example 7

 Under the conditions of Example 1, water was added to a total volume of 200 ml. The relative detection limit of phenol is 0.001 μg / ml.

 Limit 8.

 Under the conditions of Example 7, brand 140 polyurethane foam was used. The relative detection limit of phenol was 0.0003 μg / ml.

 Example 9

Under the conditions of Examples 1 and 4, 2-, 3-, 4-cresols and 1-, 2-naphthols are introduced into a vessel with a ground stopper. Data on the relative and absolute detection limits of aromatic hydroxy derivatives are given in table. 3
Example 10

 Under the conditions of Examples 1 and 4, decyl-, dodecyl-, tetradecyltrimethylammonium, cetylpyridinium and dodecylpyridinium bromides are administered. Data on the relative and absolute detection limits of phenol are given in table. 4 and 5.

 Example 11

Under the conditions of Examples 1, 4 and 10, 2-cresol and 1-naphthol are introduced into a vessel with a ground stopper. Data on the relative and absolute limits of detection are given in table. 6
Thus, the proposed method for the determination of aromatic hydroxy derivatives reduces the complexity by halving the number of stages during its implementation and is characterized by high sensitivity, the relative limit of phenol undevelopment to 0.0003 μg / ml.

Literature
1. Gabert A. Striegler E. Wasserwirtsch. 1958, N 8, B. 457.

 2. Yurchenko V.V. Zulfigarov O.S. Melnik D.N. Pilipenko A.T. Chemistry and technology of water. 1990, v. 12, N 5, p. 457.

Claims (1)

A method for determining aromatic hydroxy derivatives, including treating an alkaline analyte solution with 4-nitrophenyl diazonium tetrafluoroborate, sorbing the resulting colored azo compound, characterized in that the treatment is carried out to a reagent concentration of 0.01 0.03 M, the resulting solution is treated with cationic surfactants to a concentration of 8 · 10 ^{- 5} 2 • 10 ^{- 4} M, sorb the colored compound on polyurethane foam and measure diffuse reflection.

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