SU1242777A1 - Method of quantitative determining of methanol in air - Google Patents

Abstract

This invention relates to analytical chemistry, in particular to a method for the quantitative determination of methanol in air. The purpose of the invention is to increase the stability of the determination results when the sample is stored. The determination is carried out by passing the sample under analysis through an absorption solution of 0.005-0.05 n. sulfuric acid. The resulting solution is treated sequentially with solutions of sulfuric acid, potassium manganate, sodium sulfite, chromotropic and sulfuric acids, heated in a boiling water bath. The resulting solution was photometrized. The accuracy of determination is maintained at 100% for 7 days. 5 tab. c & (Lu 4 "" h

Description

i

The invention relates to the industrial sanitary chemistry, namely to the determination of methanol in the air environment of industrial enterprises of atmospheric air and premises.

The purpose of the invention is to increase the stability of the determination results during storage of the sample,

PRI me R. Air is drawn through an absorption device with a porous plate filled with 10 ml of OUO n, sulfuric acid solution, at a rate of 1 l / min for 20 minutes. Selected 20 liters of air. Air samples are taken in the premises of experimental prefabricated houses, where carbamide resin-based chipboard is used as a structural material.

After sampling, the liquid from the absorber O is poured into a 5–10 ml colorimetric tube. The absorber is washed with 0.01N. solution of sulfuric acid and the liquid is poured into the same tube up to the mark 10,

For the analysis, a 2 ml sample was taken into another colorimetric tube, 0.5 ml of sulfuric acid solution, 0.2 ml of 0.5% potassium permanganate solution was added and left for 5-6 minutes. Then, 1 ml of a 7% sodium sulfite solution, 0.5 ml of a 10% solution of chromatic acid and its disodium salt, 3 ml of concentrated sulfuric acid are introduced and heated for 30 minutes in a boiling water bath. After adding each reagent, the sample is thoroughly mixed. Upon cooling, the optical density of the solutions is measured at

0

2427772

750 in a cuvette with a layer thickness of 10 mm relative to the control for reagents.

The methanol content in the analyzed volume is determined according to a previously constructed calibration graph, for which construction a scale of standards is prepared, for which 0.0; 0.2; 0.5; 1.0; 2.0; 4.0; 6., 0; 8.0; 10.0; 15.0; 20.0 μg of methanol. In all test tubes with 0.01 N, the volume was adjusted to 2 ml with sulfuric acid solution. All tubes of the scale are treated similarly to samples. The concentration of methanol in the sample to be analyzed is calculated by the conventional formula. As a result of the analysis, the following concentrations were found: methanol, mg / m, samples immediately after sampling 0.75; 0.78; 0., 77; 1.38; 1.42; 1.45, the same samples analyze after 7 days 0.75; 0.78; 0.77; 1,381; 1,420; 1,450.

When air is aspirated at a rate of 1 / min, methanol is absorbed completely into an absorption device with a porous plate containing 10 ml of 0.01N. sulfuric acid solution. In the study of samples taken in 0.01 n. sulfuric acid solution after 7 days or more, the concentration of the substance in the sample, and the investigators

20

25

thirty

35

40

100% level

The results of the determination of methanol (mg / m) in the air according to the proposed and known methods under the conditions: immediately after sampling; after 4 hours; after 1 day :; after 3 days; after 7 days are presented in table 1-5, respectively. The same sample was analyzed within 7 days.

Contains methanol in the air, mg / m, using an absorption solution

0.750 0.750 0.0 0, O, L h 0.750 0.0 0.700 6.7 0, A50 40.0 0.780 0.780 0.0 0.780 0.00 0.780 0.0 0.731 6.28 O.DZO 44.9 0.770 0 , 0 0.77t 0.08 0.770 0.0 0.709 7.92 0.480 37.7

100% level

The results of the determination of methanol (mg / m) in the air according to the proposed and known methods under the conditions: immediately after sampling; after 4 hours; after 1 day :; after 3 days; after 7 days are presented in table 1-5, respectively. The same sample was analyzed within 7 days.

T a .6 l nts a 1

The methanol content in the air, mg / m, prc nspachyoplichp absorption solution

1.420 1, D20 0.0 1.42t 0.007 1.420 0.0 1.349 5.0 0.840 40.1 1.380 1.380 0.0 1.380 0.0 t, 380 0.0 1.300 5.8 0.830 39.9 1.450 t, 450 0.0 1.451 0.07 1.450 0.0 1.350- 6.9 0.850 4T, 4

The content of methanol in the air, mg / m, when using the absorption

solution

53,30,67510

58,90,68612

53,20,65515

52,11,2708

54,91,27810

55,21,24714

The methanol content, mg / m, when using the absorption

solution

Normal sulfuric acid

0.165 78 0.615 18 0.675 10 0.751 0.13 0.115 18 0.455 39.3 0.187 76 0.640 18 0.702 10 0.779 0.13 0.640 18 0.438 43.9

G1rS) long IL tlPl, 1

table 2

Table 3

Netapol content, mg / m, when using the absorption

solution

79

77

77

77

0 63917

1,13216

1,1,7917

1,21816

0.693 10 1.256 9

1 „306 8

1 ,, 305 to

The content of methanop in the eddyuh, mg / m, when using Gyglott e of a solution

-lOO0,613Ш.Э0,6858,7

.tOO 0.63818,20,7128.7

 1000,64216.60 69310

SHO-1,13517,81,2569

1001J8116,81,3167.3

1001,22015,91,3129,5

Soderkat e methanol in air, mg / m-, when using the absorbing solution

0.0 0.0

100 100

0.6P; 0 18.8 0.699 8.0 0.751 0.13 0.615 18 0.460 38.7 0.630 19.2 0.700 10.3 0.780 0.0 0.640 (8 0.430 44.9

Continuation of table 3

0.7700,00,639170, A7538 3

1,3800,01,132180,84538,8

1,, 01, t6At80,815A2,6

1.4510,131,218160,8434TS9

Table 4

0,00,62017,3 0,45838,9

0,00,64018 0,43843,9

0,00,63917 0,47538,3

0,01,14017,4 0,84538,3

0,01,16817,7 0,81542,6

0.131.21416.3 0.84839.5

Table 5

The methanol content in the exhaust, mg / m, using an absorption solution

Thus, when using S as an absorption solution of 0.005-0.05 n. Sulfuric acid solution accuracy of the method after 1-7 days is maintained equal to 82-84%. When using 0,005 n. Sulfuric acid solution determination accuracy after 7 days is 82-84%, and when using 0.05 n. sulfuric acid solution - 82-84%. When using 0.01 sulfuric acid solution, the accuracy of determination after 7 days remains at the level of 100%.

By a known method, i.e. when using distilled water as an absorption solution, the accuracy of determination after 4 hours drops to 45–47%, after 1 day to 21–24%, and after 3 days the concentration is edited. N. Rogulich

Compiled by S.Hovanska Tehred O.Gortvay

Order 3694/39 Circulation 778

VNIIP11 USSR State Committee

for inventions and discoveries 113035, Moscow-, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

1242777

8 TT extension table. five

Claims (1)

Qi of methanol in the sample is not detected, the formula of the invention A method for quantitative determination of methanol in air by passing an analyzed sample through an absorption solution, treating the resulting solution sequentially with solutions of sulfuric acid, manganese-acidic potassium, sodium sulfite, chromotropic and sulfuric acids, heating in a boiling water bath, followed by photometric measurement the resulting solution, characterized in that, in order to increase the stability of the results of the determination during storage of the sample, 0.005-0.05 N are used as the absorption solution. sulfuric acid solution. Proofreader E. Sirohman Subscription