CZ14445U1 - Chromogenic agent for determination of chlorine - Google Patents

Description

The technical solution relates to the composition of a chromogenic reagent for spectrophotometric determination of chlorine on an indicator tape intended for automatic signaling of chemical warfare agents and militarily important industrial pollutants.

BACKGROUND OF THE INVENTION

For the colorimetric, photometric or spectrophotometric determination of chlorine in air but also in water, a number of reagents and analytical systems are used, which can be divided into four groups with some simplification.

The first group of reagents consists of organic redox indicators which are oxidized by chlorine to their color forms. Classic agents of this class are benzidine derivatives, particularly o-tolidine [MOMIN, SA - Narayanaswamy, R., Anal. Chim. Acta 244, 71 (1991)], o-dianisidine [CATALA ICARDO M. et al .: Analyst 126, 2087 (2001)] or more recently 3,3 ', 5,5'-tetramethylbenzidine [SERRAT, FB: Talanta 41, 2091 (1994)]. However, other aromatic amines such as N-dimethylaniline sulfate have also gained popularity [LEGGETT, AJCHEN, NH MAHADEVAPPA, DS: Fresenius Z. Anal. Chem. 315, 47 (1983)] or N, N-diethyl-phenylenediamine [PATROVSKÝ, V .: Chem. Letters 80, 1297 (1986)]. For the preparation of particularly simple analytical means have been proposed for example amines of the formula Ar-CH ₂ -NH-CH ₂ -Ar [Rupe, CO - BAUER, R .: Pat. US 4092115 (1978)], 4,4-bis (4-dimethyl20-aminophenyl) -1,3,3,4-tetrahydro-phthalazin-1-one [HAUPTMANN, S. EPERLEIN, J. - HUNGER, P .: Pat. . DE 132903 (1978)], p-anisidine [CERBULIAS, J .: J. Chromatogr. 155, 226 (1978)] or Michler's thioketone [TUPIKOVA, EP et al .: Pat. SU 158134 (1963)].

The second group of reagents consists of organic indicators which are bleached by chlorine. Methyl orange is the most commonly used [D'AMBOISE, M. - MEYER GRALL, F .: Anal. Chim.

Acta 104, 355 (1979)], but other azo dyes [HALAMEK, E. et al .: AO CS 239708] or dyes of different chemical structures (e.g. dinitronaphthol, cresolsulfophthalein) have been described.

A third group of reagents consists of inorganic indicators such as potassium or cadmium iodide [LAMBERT, J.L. - FINA, G.T. - DIKEMAN. E. F .: Anal. Chem. 54, 828 (1982)], usually in the presence of starch, followed by the potassium bromide-fluorescein system [HARDY, J. K. et al .: Environ.

Sci. And Technol. 13, 1090 (1979)], or the stannous chloride-diphenylcarbazide system [LAMBERT, J.L .: Anal. Lett. A14 (9), 663 (1981)].

The fourth group includes all other reagents, for example the well-known Deniges reagent based on aniline and phenol [DENIGES, G .: Precis de chemie analytique. Paris 1913], a reaction system based on the formation of polymethine dyes using cyanides, pyridine and amines or other coupling components [BELJAKOV, A.A. - Kurenko, L.T .: Pat. SU 577174 (1977)], or the recently proposed mixture of reagents 4-nitrophenylhydrazine and N- (1-naphthyl) ethylenediamine dihydrochloride, which in the presence of chlorine provides a red-violet azo dye [VERMA, KK - JAIN, A. - TOWNSHEND, A. Anal. Chim. Acta 261,233 (1992)]

Many color reactions are also used in the technology of indicator tapes for gas analyzers.

For example, dry chlorine indicator tapes are produced for the FP-300 gas monitor (Riken Krimi Co., Japan) or AutoStep ™ Plus and R.I.S. (SCOTT Instruments, USA). These tapes are probably based on the use of any of the agents described.

A somewhat different technical solution is the universal tape, which is saturated with the reactive reagent only during the analysis. An example is the universal photo-colorimetric tape analyzer

FL-5501 and its upgraded version (USSR), equipped with a reactive chlorine solution containing 0.5% o-tolidine in ethanol. In addition, a reactive solution with cadmium iodide and starch was designed for the FKG-3 chlorine analyzer (USSR) [PEREGUD, E. A.

GORELIK, D. O .: Instrumental methods of atmospheric control. Khimija.

Leningrad 1981].

The essence of the technical solution

The essence of the invention lies in the composition of a chromogenic agent, i.e. a mixture of cyclic hydrazine or hydrazone and an aromatic amine, which in the presence of chlorine provides intensely colored reaction products. The mechanism of the reaction is based on the oxidation of cyclic hydrazine or hydrazone to diazo-cation, which electrophilically coupled with the aromatic amine to the corresponding azo dye according to the general scheme:

R-NH-NH ₂ ^oxidation -> [RN = N] ^{+ 10} [RN = N] ⁺ + R ^ Hz - ^ Κ-ΝξΝ-Κ'Ν ^

4-Amino-5-hydrazino-5-mercapto-1,2,4-triazole (Purpald®) or 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) in the mixture with coupling component N is suggested as sensitive chromogenic reagents providing reactive diazonium salts. - (1-naphthyl) ethylenediamine dihydrochloride (NEDD, Bratton's reagent). In the first case, the end product is red15 violet triazolium azo dye, in the second blue benzothiazolium azo dye.

Color changes on a cotton cloth impregnated with silica gel on which a drop of reagent is measured and a chlorine gas sample is sieved (or otherwise applied): a homogeneous and very stable red-violet or blue-violet hue develops at the contact point. lights reflected off the tape.

Instead of NEDD, other coupling agents can be used which provide shades of different shades, for example 1-naphthylamine, or 1-naphthol, 2-naphthol, phenol and the like.

The proposed composition of the chromogenic reagent has two main advantages: (1) high homogeneity and stability of ribbon coloring, which facilitates its spectrophotometric evaluation, and (2) the choice of individual components allows reagent penetration in a universal tape system and chromogenic reagent set, such as designed hydrazine and hydrazone can be used to determine formaldehyde [LAMBERT, JL et al., Anal. Lett. A17 (17), 1987 (1984); FRIND, H. - HENSEL, R., Fresenius Z. Anal. Chem. 312, 237 (1982)] and a coupling component for the determination of nitrogen dioxide [LYSHKOW, N. A .: Pat. US 4115067 (1978)] or CR police substances [HALAMEK, E. - KOBLIHA, Z. - FOLDEŠI, V .: Talanta 40,1189 (1993)].

Examples

Example 1

The chromogenic reagent for spectrophotometric determination of chlorine on the tape contains a 0,5% solution of 4-amino-5-hydrazino-5-mercapto-1,2,4-triazole, a 0,2% solution of N- (1-naphthyl) ethylenediamine dihydrochloride, 0% phosphoric acid solution and 5.0% glycerol solution in distilled water-ethanol (1: 1). The individual components are separately dispensed into glass ampoules or plastic capsules. The chromogenic reagent is prepared by mixing the components and applied to the indicator tape before sampling the contaminated air.

Example 2

The chromogenic reagent for the spectrophotometric determination of chlorine on the tape contains a 0.4% solution of 3-methyl-2-benzothiazolinone hydrazone hydrochloride, a 0.2% solution of N- (lnaphthyl) ethylenediamine dihydrochloride and a 5.0% solution of glycerol in distilled water. The individual components are separately dispensed into glass ampoules or plastic capsules. The chromogenic reagent is prepared by mixing the components and applied to the indicator tape before sampling the contaminated air.

-2EN 14445 Ul

Example 3

The chromogenic reagent contains two components. The first component contains a 0.6% solution of 4-amino-5hydrazino-5-mercapto-1,2,4-triazole and an 8.0% solution of glycerol in ethanol, the second component contains a 0.3% solution of N- (1-naphthyl) dihydrochloride ) of ethylenediamine and a 5.0% solution of phosphoric acid in distilled water. Both components are applied to the indicator tape gradually before sampling of the contaminated air.

Example 4

The chromogenic reagent contains two components. The first component contains a 0.6% solution of 3-methyl-2-benzothiazolinone hydrazone hydrochloride and an 8.0% solution of glycerol in distilled water, the second component contains a 0.3% solution of N- (1-naphthyl) ethylenediamine dihydrochloride in distilled water . Both components are applied to the indicator tape gradually before sampling of the contaminated air.

Example 5

The chromogenic reagent as set forth in Example 2 can be stabilized by the addition of sodium sulfite. Dissolve 0,01-0,5 mg of Na ₂ SO ₃ in a volume of 100 ml of reagent.

The examples given are illustrative only and do not cover all possible variations in the composition of the chromogenic agent. After saturation of the indicator strip prepared from cotton impregnated with silica gel to increase its sorption capacity, they are suitable for spectrophotometric determination of chlorine gas from a concentration of at least 0.1 mg / m ₃ after air extraction of 1.0 dm ³ .

Industrial applicability

The chromogenic reagent of the present invention is useful for saturating an indicator tape into an automatic warrant of chemical warfare agents and militarily significant industrial pollutants on a spectrophotometric principle. It can be used not only in the military, but also in the civilian sector, for example in monitoring the working environment.

Claims (1)

25 1. A chromogenic reagent for the determination of chlorine in the atmosphere by means of an indicator tape in an automatic signaling device based on the spectrophotometric principle, characterized in that it contains a mixture of cyclic hydrazine or hydrazone, preferably 4-amino-5-hydrazino-5-mercapto1,2,4-triazole or 3-methyl-2-benzothiazolinone hydrazone hydrochloride, a coupling agent, preferably N- (1-naphthyl) ethylenediamine dihydrochloride, which is stabilized by the addition of 30 glycerol and phosphoric acid.