RU2386127C2 - Method for spectrophotometric determination of cyanide anion in water based on reaction thereof with chromogenic azoaromatic disulphide through micellar catalysis - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method involves treatment of the solution of a sample with aqueous solutions of 4, 4'-bis(2-oxy-6,8-disulpho-1-naphthylazo)diphenylsulphide, potassium hydroxide and cetyltrimethylammonium chloride in volume ratio of 2:1:1:1 respectively, with subsequent measurement of optical density and determination of content of the cyanide anion using a calibration curve.

EFFECT: simpler and faster analysis.

3 dwg

Description

The invention relates to the field of analytical chemistry of inorganic and organic compounds. Due to the fact that cyanide hydrocyanic (hydrocyanic) acid and its cyanide salts are widely used in various industries and the national economy, while possessing high physiological activity, many ministries and departments are interested in implementing the invention: the Ministry of Health, Internal Affairs, and Defense and Ecology of the Russian Federation.

In order to detect and determine cyanidanion, a large number of methods have been proposed using physicochemical and chemical analysis methods [Williams W.J. Determination of anions. Moscow, Chemistry, 1982, 622 pp.] One of the important objects for analysis for the presence and quantification of cyanidanion is water and various systems based on it. However, there are few known simple, rapid methods for the determination of cyanides in water, which differ in the possibility of quantitative direct determination to its maximum permissible concentration of 1 · 10 ^-2 mg / l [Maximum allowable concentrations of harmful substances in air and water. Leningrad, Chemistry, 1975, 455 pp.].

The most common method for determining cyanidanion is the Koenig method, which is based on the conversion of cyanidanion to chlorine (or bromine) cyan, the interaction of the latter with pyridine, the destruction of the resulting product in an alkaline medium, the combination of the resulting glutacondialdehyde with the component that forms the brightly colored compound, and the measurement of optical density this compound [Fischer W., Link R. German Patent No. 2517484 of 04/19/1975; ObO - 5 · 10 ^-2 mg / l].

Due to the widespread use of the method for determining cyanidanion according to Koenig and its high sensitivity, this method is taken as a prototype. The disadvantage of the prototype is the complexity of the determination method and the need to use many components, which slows down and increases the cost of analysis.

The aim of the invention is the determination of cyanidanion in water, based on the micellar catalysis of the interaction of cyanidanion with chromogenic disulfides of the azoaromatic group.

This goal was achieved, firstly, by using a new water-soluble chromogenic disulfide, characterized by a high molar absorption coefficient, such as 4,4-bis (2-hydroxy-6,8-disulfo-1-naphthylazo) -diphenyl disulfide (ALS-sulfo ) Secondly, the goal is achieved by using cationic micelles during the analysis, in the presence of which nucleophilic interactions are accelerated. Using a water-soluble chromogenic disulfide and a cationic detergent such as cetyltrimethylammonium chloride [CTMAC], it was possible to develop a method for spectrophotometric determination of cyanidanion in water based on its nucleophilic interaction with chromogenic disulfides. The limit of determination of the developed methodology for the analysis of cyanidanion in water allows you to set the maximum permissible concentration of cyanidanion.

When using BAS-sulfo chromogenic disulfide, the initial color - orange - (λ _max = 495 nm) changes to violet (λ = 555 nm).

The process diagram for the determination of cyanidanion with chromogenic BAS-sulfo disulfide is presented in Figure 1.

Used equipment and reagents

Spectrophotometer SF-103 (Concentration photoelectric colorimeter - KFK-2) - 1 PC. 1.0 ml dispensers - 1 set) 10 ... 15 ml tubes - 20 pcs. Test tube rack - 1 PC. Volumetric flasks per 100 ml - 4 things. Stopwatch - 1 PC.

4,4′-bis (2-hydroxy-6,8-disulfo-1-naphthylazo) diphenyl disulfide (BAS-sulfo) [Copyright certificate 1177296 USSR, Veksler K.V., Trakhanova G.M., Chernova N.G., No. SN 1263695, publ. 10/15/96, Bull. No. 38]

Potassium cyanide, “chda” (98.6%)

Cetyltrimethylammonium chloride, “h”, “Reachim”, TU 6-09 05-807-78

Potassium oxide hydrate "hch" GOST 4203-65

Preparation of stock solutions

A solution of potassium cyanide is prepared by dissolving in water a sample taken on an analytical balance with an accuracy of ± 0.0001 g based on a concentration of 1 · 10 ^-1 mg / ml. From the main (base) solution by the method of sequential dilution, solutions are prepared to construct a calibration curve up to 1 · 10 ^-6 mg / ml.

Method for determination of cyanadanion

1.0 ml of a 10 ^-4 M solution of BAS-sulfo in water, 1.0 ml of a 0.1 M aqueous solution of potassium oxide hydrate, 1.0 ml of a 0.05 M aqueous solution of cetyltrimethylammonium are added to 2.0 ml of the studied aqueous solution of the sample. chloride, which is the volume ratio of the components 2: 1: 1: 1, the stopwatch starts. The reaction mixture is stirred and poured into a cuvette 1 = 1.0 cm spectrophotometer. The optical density is measured after one minute at λ = 555 nm.

The results obtained in the analysis of standard solutions of cyanidanion are presented in Figure 2. Based on these results, a calibration graph is constructed for the quantitative determination of cyanidanion (Figure 3) in water.

Claims (1)

A method for spectrophotometric determination of cyanidanion in water, comprising treating a sample solution with aqueous solutions of 4,4′-bis (2-hydroxy-6,8-disulfo-1-naphthylazo) diphenyl sulfide, potassium hydroxide and cetyltrimethylammonium chloride in a volume ratio of 2: 1, respectively: 1: 1, followed by measuring the optical density and determining the content of cyanidanion according to the calibration graph.

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