RU2563838C1 - Method of express-detection of aggressive chemical substances - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method consists in spraying an indicator formulation from a distance of 10-15 centimetres from an object surface with the application of an aerosol device, made in the form of a hermetic case, filled with the indicator formulation, and a pump-sprayer, a conclusion about the presence of an aggressive chemical substance is made by the characteristic change of the indicator colour on the surface of the analysed object in accordance with the standard on the aerosol device label. Spraying of the indicator formulation is realised by a mono-disperse aerosol, to detect oxidants applied is a solution in weight percents: potassium iodide - 0.1-0.4; starch, preliminarily processed by heating to a temperature of 190°C in glycerin for 0.5 hour with periodical collecting a sample for dissolution in cold water until starch precipitation stops - 0.1-0.3; glycerin - 5-20; acetic acid - 0.3-1.5; sodium trihydrate acetate - 0.4-3; distilled water - to 100, to detect substances of an alkaline type a 0.5-1 wt % solution of phenolphthalein in ethyl alcohol is applied, to detect substances of an acidic type a 0.05-0.1 wt % solution of each individually or a mixture of two indicators methyl red and methyl yellow in a volume ratio of 1:1 in ethyl alcohol, to detect weak organic acids of an acetic acid type a 0.05-0.1 wt % solution of 4-diethylaminoasobenzol in ethyl alcohol is applied, to detect asymmetric dimethylhydrazine (heptyl) and ammonia a 10-20 wt % solution of cobalt (II) acetate in distilled water is applied.

EFFECT: increase of sensitivity, self-descriptiveness and reliability of detection.

3 tbl, 2 dwg

Description

The invention relates to the field of analytical chemistry, and in particular to methods of express detection of contamination of surfaces of objects with aggressive chemicals.

Acidic and alkaline substances, as well as oxidizing agents and reducing agents, are considered as aggressive chemicals.

Acidic substances include strong (sulfuric, nitric, hydrochloric and others) and weak (acetic and other) acids.

Alkaline substances include strong (potassium hydroxide, sodium hydroxide and others) and weak (ammonium hydroxide and others) bases.

Oxidizing agents include concentrated nitric, concentrated sulfuric acid, hydrogen peroxide and others.

Reducers include asymmetric dimethylhydrazine (heptyl), organic amines, ammonia, and others.

The need to develop a method for the rapid detection of all four of these types of aggressive chemicals is due to the fact that the bottling of these chemicals can lead to chemical burns to working personnel, and the mixing of acids with alkalis, oxidizing agents with reducing agents can lead to explosions and fires. Therefore, the joint storage of these substances is unacceptable.

There is a method of rapid detection of disinfectants with an active substance of an oxidizing nature on the surfaces of objects and detect the completeness of disinfection, which consists in spraying indicator formulations on the surface of the object using an aerosol device made in the form of a sealed enclosure filled with a reagent and a spray pump, while the presence of oxidative chemicals are judged by a characteristic change in the color of the indicator on the surface of the examined object in accordance with coupon on the label of the aerosol apparatus (patent RU 2436082 C2, Cl. G01N 31/22, publ. 10.12.2011).

The method of rapid detection of substances of an oxidizing nature allows detection on horizontal, inclined and vertical surfaces, based on the application of indicator formulations by irrigation on the analyzed surface using an aerosol device. As an indicator formulation, a composition is used consisting of the following components (in mass percent): potassium iodide - 0.1-0.2; starch - 0.1-0.2; acetic acid - 1.0-1.5; sodium acetate three-water - 2.0-3.0; glycerin - 5.0-10.0; distilled water - up to 100.

Using this method, it is possible to detect the completeness of disinfection of surfaces after at least 0.5 hours and no later than 2 hours after disinfection by the appearance of an indication effect - blue staining of the object.

The disadvantage of this method is that during storage, starch precipitates in the form of sediment, which reduces the sensitivity of detection of oxidizing agents, impairs the visibility of the display effect and leads to clogging of the spray pump of the aerosol device, as a result of which the aerosol device stops spraying the indicator formulation.

The method does not allow the detection of other types of aggressive chemicals (reducing agents, substances of an acidic and alkaline nature).

The technical result of the invention is to increase the sensitivity of the detection of oxidizing agents, the visibility of the indicator effect, increasing the duration of use of the aerosol device and providing detection along with oxidizing agents of other aggressive chemicals - asymmetric dimethylhydrazine, ammonia, acidic and alkaline substances.

This technical result is achieved by spraying the indicator formulation onto the surface of the object using an aerosol device made in the form of a sealed enclosure filled with a reagent and a spray pump, while the presence of an aggressive chemical substance is judged by a characteristic change in the color of the indicator on the surface of the object being examined in accordance with the standard on the label of the aerosol device, spraying the indicator formulation is carried out from a distance of 10-15 centimeters about surface monodisperse aerosol for detecting oxidizing solution used (in weight percent): Potassium iodide - 0.1-0.4; starch pretreated by heating to a temperature of 190 ° C in glycerol for 0.5 hours with periodic sampling for dissolution in cold water until no starch precipitates - 0.1-0.3; glycerin - 5-20; acetic acid - 0.3-1.5; sodium acetate three-water - 0.4-3; distilled water - up to 100, for the detection of alkaline substances use a 0.5-1% solution of the phenolphthalein indicator in ethyl alcohol, for the detection of acidic substances use a 0.05-0.1% solution of each individually or a mixture of two indicators of methyl red and methyl yellow in a ratio of 1: 1 by weight in ethyl alcohol, to detect weak organic acids (acetic and others), use a 0.05-0.1% solution of 4-diethylaminoazobenzene in ethyl alcohol, to detect asymmetric dimethylhydrazine (heptyl) and ammonia A 10-20% solution of cobalt (II) acetate in distilled water is used.

To eliminate the disadvantages of the existing method, instead of the usual water-soluble starch, we used water-soluble starch in the method for detecting oxidizing agents obtained by its additional processing. This method consists in the heating and aging of starch in glycerol at a temperature of 190 ° C for about 0.5 hours with periodic sampling for solubility in cold water until no starch precipitates.

To detect substances of an alkaline and acidic nature, asymmetric dimethylhydrazine and ammonia in the proposed method, the corresponding indicator compositions mentioned above were used.

The results of comparative tests of the known and proposed methods are shown in table 1.

As follows from the data of table 1, when applying the proposed method with additionally treated starch, it does not fall out of the formulation in the form of sediment for at least 2 years, maintaining the sensitivity, visibility of the indicator effect and the health of the aerosol device, which significantly improves the characteristics of the proposed method.

The determination of the presence of asymmetric dimethylhydrazine was previously carried out by indicating, including its contact with the reagent of the indicator formulation with a color transition, contacting was carried out on the surface by spraying the indicator formulation using an aerosol device made in the form of a sealed housing, filled with the formulation, with a spray head, and as a formulation used solutions of cobalt (II) chloride, nitrate or sulfate in water, while the aerosol device could be to reagent repeatedly.

As shown by tests of the formulation, other reducing agents, in particular ammonia, can be detected using the latter.

The disadvantage of this method is that during storage due to the hydrolysis of salts formed by a strong acid and a weak base - chloride, nitrate or cobalt sulfate, strong inorganic acids are released, respectively, hydrochloric, nitric and sulfuric, which leads to a shift in the pH of the solution to acidic side, strengthening due to this corrosion and premature failure of the metal elements of the spray device.

To eliminate this drawback, in the proposed method, we used a solution of cobalt acetate as an indicator formulation of the aerosol device. During the hydrolysis of this salt, formed by a weak acid and a weak base, a weak organic acid is formed during storage; acetic acid and a weak base, the pH of the solution changes slightly and the formulation has a significantly lower ability to cause corrosion of the metal elements of the spray device.

The results of comparative tests of the known and proposed methods are shown in table 2.

Table 2 - The results of a comparative assessment of the known and proposed methods for the detection of UDMH

As follows from the data of table 2, the sensitivity and visibility of the obtained indication effect by the proposed method after 2 years of storage of the aerosol device does not deteriorate, and the spray device remains operational for a long time.

Indicator papers and tickets were previously used to detect alkaline substances. The disadvantage of this method is that papers and tickets allow detection only directly at their contact with the surface being examined. In this case, direct contact of the operator with the analyzed surface is necessary, it is impossible to detect contamination of surfaces to which the operator’s hand is limited.

To address these shortcomings, we propose a method of aerosol spraying indicator formulations on the analyzed surface. The property of the phenolphthalein indicator was used to instantly change color from colorless to raspberry in an alkaline environment. Based on this, in the proposed method, the indicator is used in the form of an aerosol created using an aerosol device, the indicator being a 0.5-1% solution of phenolphthalein in ethanol.

The results of the detection of alkaline substances by a known proposed method are shown in table 3.

The use of a solution of a lower concentration leads to a deterioration in the visibility of the resulting indication effect. The use of a solution of a higher concentration does not lead to a significant improvement in the indicator effect, it is limited by the solubility of phenolphthalein in alcohol and an increase in the indicator consumption.

To detect acidic substances, a method using indicator papers and tickets was also previously used.

We have applied the method of aerosol spraying of the indicator formulation onto the test surface. In this case, the ability of the methyl red indicator was used to instantly change the color from yellow to red when changing from a neutral to acidic environment (in the pH range 4.4–6.2).

The methyl yellow indicator changes color from yellow to red in a more acidic pH range (2.9-4.0). Considering that both indicators equally change color from yellow to red in an acidic environment, we recommended the use of alcohol solutions as each of them individually, and their mixture in a volume ratio of 1: 1.

Based on this, for the detection of acidic substances in our method, we use aerosol spraying of an indicator formulation, which is a solution of one or a mixture of two indicators of methyl red and methyl yellow in a volume ratio of 1: 1 in ethyl alcohol with a total indicator concentration of 0.05-0, one%. The use of a more diluted indicator solution leads to a deterioration in the sensitivity and visibility of the indicator effect. A more concentrated solution cannot be prepared due to the limited solubility of the indicators in the alcohol solution. In addition, the presence of a dark color in the indicator solution in this case masks the indication effect.

To increase the sensitivity, visibility and reliability of the detection of weak organic acids such as acetic acid, it is proposed to use a 0.05-0.1% solution of 4-diethylaminoazobenzene in ethyl alcohol as an indicator formulation of an aerosol device.

To obtain a visual indicator effect on the surface of objects using the proposed aerosol devices, it was necessary to ensure the application of a finely dispersed aerosol of an indicator formulation on the surface of the monodisperse jet.

Previously, fluorine and chlorine-containing freons were widely used for spraying liquids. Currently, due to their destructive effect on the ozone layer of the atmosphere, the use of freons is significantly limited.

Methods based on creating excessive pressure in an aerosol device due to nitrogen nitrogen or atmospheric air have found wide application for spraying formulations.

However, the use of compressed nitrogen as a repellent requires special facilities for its production and refueling of aerosol devices.

The use of compressed air can be provided by the very design of the aerosol device. At the same time, air pressure is created by repeatedly pressing a special pear like spraying cologne in a hairdresser.

The disadvantage of this method is the need for a second channel for the output of the sprayed formulation.

Recently, aerosol devices have been used, in which compressed air pressure is created by repeatedly pressing the spray head of the pump.

In addition, conventional spraying devices, as a rule, do not allow to obtain a jet of fine monodisperse aerosol, which leads to erosion of the indication effect on the surface of objects.

Therefore, we have applied a spraying method based on the creation of pressure using a special design of the spray pump.

When the nozzle of the pump sprayer is repeatedly pressed in the bottle, excess air pressure is created and due to this, the indicator formulation is fed into the spray pump with its subsequent spraying onto the analyzed surface.

The design of the aerosol device and the spray pump used are shown in figures 1, 2.

The aerosol device for the detection of aggressive chemicals is a 150 ml spray can equipped with a spray bottle and filled with the appropriate indicator formulation for aggressive chemicals.

The aerosol device (AC) shown in FIG. 1 consists of two components — the spray pump 1 and the bottle 2. In turn, the spray pump in accordance with FIG. 2 consists of the following parts: cap 3, buttons 4, pump-sprayer body 5, gaskets 6, piston 7, lock case 8, ball 9, base of lock 10, spring 11, valve body 12, tube 13. Bottle diameter and height of control unit selected taking into account the anthropometric characteristics of men in accordance with GOST 21114.

The applied AU also meets the requirements of GOST R 51760 for consumer plastic containers. The aerosol device is made of materials resistant to the indicator formulation.

The advantages of applying the method with an aerosol device over known methods, in particular over a piece of paper indicator or indicator tissue, are as follows:

longer shelf life of indicator formulation (more than 2 years); no need to use additional reagents for detection;

no need for direct contact of the operator with the analyzed surface;

the multiple use of one package (at least 100 times), which allows you to repeatedly determine the pollution of the surface of the object; maintaining operability in the temperature range from minus 5 to plus 40 ° C;

a large control area is provided;

The proposed aerosol device (Fig. 1) for express detection of aggressive chemicals on the surfaces of objects is characterized in that due to the selection of material and the relative position of the parts relative to each other, the surface is irrigated with a monodisperse jet using an indicator formulation, which eliminates the erosion of the indication effect.

The conducted experimental storage showed the stability of the proposed indicator formulations during storage and maintaining the operability of the proposed method with aerosol devices for at least 2 years.

The technical result that can be achieved as a result of using the proposed invention is the provision of quick detection of the presence of traces of all types of aggressive chemicals on large areas of the surfaces to be examined. Moreover, the detection of these substances is carried out by the consistent use of all four aerosol devices.

If the nature of the surface contamination is known, then one or more appropriate aerosol devices are used in series.

Claims (1)

The method of rapid detection of aggressive chemicals on the surfaces of objects, which consists in spraying the indicator compound from a distance of 10-15 centimeters from the surface of the object using an aerosol device made in the form of a sealed enclosure filled with the indicator compound and a spray pump, with the presence of aggressive chemical substances are judged by a characteristic change in the color of the indicator on the surface of the examined object in accordance with the standard on the label of the aerosol device characterized in that the spraying of the indicator formulation is carried out with a monodisperse aerosol; to detect oxidizing agents, a solution is used in mass percent: potassium iodide - 0.1-0.4; starch pretreated by heating to a temperature of 190 ° C in glycerol for 0.5 hours with periodic sampling for dissolution in cold water until no starch precipitates - 0.1-0.3; glycerin - 5-20; acetic acid - 0.3-1.5; sodium acetate three-water - 0.4-3; distilled water - up to 100, for the detection of alkaline substances use a 0.5-1 wt.% solution of the phenolphthalein indicator in ethanol, for the detection of acidic substances use a 0.05-0.1 wt.% solution of each separately or a mixture of two indicators of methyl red and methyl yellow in a volume ratio of 1: 1 in ethyl alcohol, to detect weak organic acids such as acetic acid, use a 0.05-0.1 wt.% solution of 4-diethylaminoazobenzene in ethyl alcohol, to detect asymmetric dimethylhydrazine (heptyl ) And ammonia using 10-20 wt.% Cobalt acetate (II) in distilled water.

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