SU728083A1 - Method of determining acetone vapours in air - Google Patents

Description

The invention relates to the field of analytical chemistry, in particular, to the construction of automatic gas analyzers for measuring the maximum permissible concentration (MPC) of vapor, acetone in the air.

A known method for determining acetone vapors in air is by passing an air sample through silica gel impregnated with hydroxylamine hydrochloride and bromophenol blue solution followed by photocolorimetric measurement of a colored layer of silica gel 1.

The disadvantage of this method is its low sensitivity.

The purpose of the invention is to increase the sensitivity of the method.

This goal is completed by the described method, which is that the tissue tape is pre-impregnated with a solution containing 0.15-0.25% hydroxylamine hydrochloride and 0.8-1.2% of the indicator of bromophenol blue, dried and before treatment with the analyzed air The tape is additionally wetted with a solution containing 0.25–3% th hydroxylamine hydrochloride and 0.1–0.15% indicator of bromophenol blue, and after treatment with air to be analyzed, it is fluorocolorimetricated. Examples of the preparation of solutions.

1. Preparation of sensitive solution No. 1 for preliminary impregnation of fabric tape.

To 75 ml of a 0.15% solution of hydrochloride hydroxylamine, 17.5 ml of a 0.8% alcoholic solution of bromophenol blue blue indicator and 10 ml of 0.04N sodium hydroxide solution are added. The solution is thoroughly mixed.

2. Preparation of the indicator solution 2 for wetting the fabric tape prior to its treatment with the analysis of the air supplied.

To 75 ml of a 0.25% hydroxylamine hydrochloride solution, 17.5 ml of a 0.1% alcoholic bromophenol blue indicator solution and 10 ml of a 0.02 N sodium hydroxide solution are added. The solution is thoroughly mixed.

3. Preparation of sensitive solution No. 3 for preliminary impregnation of fabric tape.

To 75 ml of a 0.25% hydroxylamine hydrochloride solution are added

17.5 ml of 1.2% alcoholic indicator solution of bromophenol blue and 10 ml of 0.04N sodium hydroxide solution. The solution is thoroughly mixed.

4. Preparation of the indicator solution No. 4 for wetting the fabric tape before it is fed into the reaction gaomeanalie ator reaction yamer. To 75 ml of a 0.3% hydrochloric acid hydrochloride solution, 17.5 ivin of a 0.15% alcoholic solution of bromophenyl blue indicator and 10 ml of 0.02 N sodium hydroxide solution are added. The solution is carefully mixed.

Examples of the use of solutions.

1. For experimental investigations, use a basic photocolorimetric gas analyzer, a tape detector, of the type FLS1.1. The output voltage of the gas analyzer is measured using an electronic, BK7ssl voltmeter. A gas mixture with a constant acetone vapor content of 200 mg / m in air is passed through the gas analyzer.

2. Use indicator tapes impregnated with the following solutions:

solution number 1 and the tape is dried;

solution number 3 and the tape is dried;

solution number 1 (tape wet);

solution number 3 (tape wet);

solution number 1, the tape is dried and moistened with solution number 2

before measurement;

with solution No. 3, the tape is dried and 5 is wetted with solution No. 4 before measurement.

The results of using the solutions are given in table. one.

Table

0.0

0.0

200 - From table. Figure 1 shows that in the case of using a fabric tape impregnated with a sensitive solution and dried, the reaction on the tape does not proceed and, therefore, the sensitivity of the gas analyzer is equal to zero. Using a fabric tape moistened only with solution 1 (No. 3) does not provide sufficient sensitivity . Additionally, the dependence of the voltage at the outlet of the gas analyzer on the content C, is presented. hydroxylamine hydrochloride and Cgop bromophenol blue concentrates in solutions 1, 2 (see drawing). From the drawing, it follows that the most optimal concentrations of hydroxylamine hydrochloride and the bromophenol blue indicator are those found in this method.

ABOUT

ABOUT

42 89

39 82

39.4

32.5

+ 3.0 -7.0

3.0 Examples of the method of analysis. 1. In a photocolorimetric gas analyzer set, pour the indicator tape, soaked in solution number 1 and dried. Before feeding the tape into the reaction chamber of the gas analyzer, it is moistened to a wet state with solution no. 2 using an automatic metering device. A vapor-air mixture is sucked through the reaction chamber of the gas analyzer, with a given concentration of acetone. The amount of acetone vapor in the air is determined by the photocolorimetric method on a FEC-M photoelectric colorimeter. The accuracy of chemical analysis is not lower than 2.5%. The results of laboratory tests are given in table. 2

107

162

230 272

A: The standard deviation of each measurement (for each cycle of the gas analyzer operation) does not exceed 2% of the measurement range.

2. In the gas analyzer install tape, impregnated with solution number 3 and dried. Before being fed into the reaction, the standard deviation of a single measurement (for each cycle) was 2.5% of the measuring range. neither

3. A white tissue tape is installed in the gas analyzer and moistened with solution No. 1 to a wet state.

Continuation of table 2

-5.0 +6.0 -9.0 +4.0

  1 onnuy chamber it is wetted to a wet state with a solution 4. The graduation of the secondary device was adjusted for the maximum concentration of acetone vapors.

15 The results of laboratory tests are given in table. 3

T a b l and c a 3

before feeding it into the reaction chamber (similar to the known method). The graduation of the secondary device corresponds to a measuring range of 0-300 mg / m.

The results of laboratory tests are given in table. four.

Claims (1)

T a b c a 4 - / - v-. ... 7 .. -:. From tab. 4 th & Bm, the sensitivity of the gas analyzer to the proposed measurement method substantially exceeds the sensitivity of the gas analyzer by a known measurement method, especially for small concentrations of acetone vapors in the air. Formula of the invention by the photocolorimetric method using hydrochloric acid Lamine A and Brol4feiolu Blue indicator, characterized in that, in order to increase the sensitivity of the method, the tissue tape is pre-impregnated containing 0.15-0.25% hydroxylamine hydrochloride and 0.81, 2% bromophenol blue indicator, dried and before treatment with the analyzed air, the tape is additionally moistened with a solution containing 0.25-3.0% hydroxylamine hydrochloride and 0, 1-0.15% indicator bromophenol blue, and after processing the analyzed air photocolorimeter. Sources of information taken into account in the examination of 1, Peregud, EA, Bykovska, M.S., and Gernet, E.V. Rapid methods for the determination of harmful substances in the air. M., Chem. 1970, p. 206-209 (prototype).