Classifier of State Standards. GOST 4204-77 - Reagents. Sulfuric acid. Technical conditions. KGS: Chemical products and rubber-asbestos products, Reagents and highly pure substances. GOST standards. Reagents. Sulfuric acid. Technical conditions. class=text>

GOST 4204-77

Reagents. Sulfuric acid. Specifications

GOST 4204-77
(ST SEV 3856-82)

Group L51

STATE STANDARD OF THE USSR UNION

Reagents
SULFURIC ACID
Specifications
Reagents. Sulfuric acid. Specifications

OKP 26 1212 0021 05

Date of introduction 1978-07-01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the USSR Ministry of Chemical Industry
DEVELOPERS

V.G.Brudz, I.L.Rotenberg (topic leader), L.Ya.Mazo, Z.A.Zhukova, L.V.Kidiyarova, O.S.Ryzhenkova, N.P.Nikonova, T.G. Manova

2. APPROVED AND ENTERED INTO EFFECT by Resolution of the State Committee of Standards of the Council of Ministers of the USSR dated June 17, 1977 N 1513

3. Inspection frequency - 5 years

4. The standard contains all the requirements of ST SEV 3856-82

5. The international standard ISO 6353-2-83 (R.37) has been introduced into the standard

6. INSTEAD GOST 4204-66

7. REFERENCE REGULATIVE AND TECHNICAL DOCUMENTS

8. The validity period was lifted by decision of the Interstate Council for Standardization, Metrology and Certification (Protocol 5-94)

9. REISSUE (October 1994) with Amendments No. 1, 2, approved in February 1984, June 1990 (IUS 6-84, 9-90)
An amendment has been made, published in IUS No. 1, 2014
Amendment made by database manufacturer

This standard applies to the reagent - sulfuric acid, which is a colorless, transparent, oily liquid, odorless, without sediment, miscible with water (with strong heating) and with alcohol.
Formula HSO.
Molecular mass (according to international atomic masses 1971) - 98.08.
Density about 1.83 g/cm.

1. TECHNICAL REQUIREMENTS

1. TECHNICAL REQUIREMENTS

1.1. Sulfuric acid must be manufactured in accordance with the requirements of this standard according to technological regulations approved in the prescribed manner.

1.2. In terms of physical and chemical indicators, sulfuric acid must comply with the requirements and standards specified in the table.

Note. Sulfuric acid with the standards indicated in brackets may be produced until 01/01/95.

(Changed edition, Amendment No. 1, 2).
(Amendment. IUS No. 1-2014).

1.3. Sulfuric acid with the qualification “chemically pure” and “pure for analysis”, intended for the analysis of ethyl alcohol, must withstand the Savall test according to clause 3.13.

1.4. Sulfuric acid is permitted in other concentrations provided that the other requirements of this standard are met.

1.5. The manufacturer is allowed to periodically determine (once a month) the mass fraction of chlorides, nitrates, heavy metals, arsenic and selenium in sulfuric acid made from natural and gas sulfur (according to GOST 127-76).

1.4 and 1.5. (Introduced additionally, Amendment No. 2).

2. ACCEPTANCE RULES

2.1. Acceptance rules - according to GOST 3885-73.

2.2. Samples from large-sized containers (tanks, containers), used by agreement between the manufacturer and the consumer, are taken with a sampler made of fluoroplastic.

3. METHODS OF ANALYSIS

3.1a. General instructions for conducting analysis - according to GOST 27025-86.
When weighing, use general purpose laboratory scales such as VLR-200 g and VLKT-500g-M or VLE-200 g.
It is allowed to use other measuring instruments with metrological characteristics and equipment with technical characteristics no worse, as well as reagents of quality no lower than those specified in this standard.

3.1. Samples are taken according to GOST 3885-73.
The total mass of the average sample must be at least 1.5 kg (800 cm).
The volume fraction of sulfuric acid required for analysis is taken with a safe pipette or measuring cylinder with an error of no more than 1%.
(Changed edition, Amendment No. 1, 2).

3.2. Defining Appearance
The determination is carried out according to GOST 14871-76 and GOST 27025-86.
The drug is considered to comply with the requirements of this standard if the analyzed drug, observed against the background of milk glass in transmitted light, does not differ from distilled water.

3.3. Determination of the mass fraction of sulfuric acid

3.3.1. Equipment, reagents and solutions.
Burette with a capacity of 50 cm with a division value of 0.1 cm.
Flask Kn-2-500-40 THS or Kn-1-500-29/32 THS according to GOST 25336-82.
Cylinder 1(3)-250 according to GOST 1770-74.
Methyl red (indicator) according to TU 6-09-5169-84, solution with a mass fraction of 0.1%, prepared according to GOST 4919.1-77.

Methyl orange (indicator) according to TU 6-09-5171-84, solution with a mass fraction of 0.1%; prepared according to GOST 4919.1-77.
Sodium hydroxide according to GOST 4328-77, solution concentration (NaOH) = 1 mol/dm (1 N); prepared according to GOST 25794.1-83.
Mixed indicator, methyl red and methylene blue; prepared according to GOST 4919.1-77.

3.3.2. Carrying out analysis
About 1.0000 g of the drug is weighed in a sealed ampoule (the weighing result in grams is recorded to the fourth decimal place), then the ampoule is placed in a flask containing 200 cm of water. The ampoule is broken with a glass rod with a flat end and the contents of the flask are mixed. Add 5 drops of a mixed indicator to the solution and titrate with sodium hydroxide solution until it turns green.

3.3.3. Processing the results
The mass fraction of sulfuric acid in percent () is calculated using the formula

where is the volume of sodium hydroxide solution with a concentration of exactly (NaOH) = 1 mol/dm (1 N) used for titration of the analyzed drug, cm;
0.04904 - mass of sulfuric acid corresponding to 1.00 cm of sodium hydroxide solution with concentration exactly (NaOH) = 1 mol/dm (1 N), g;
- mass of a sample of the analyzed drug, g.
It is allowed to determine the mass fraction of sulfuric acid in the presence of a methyl orange or methyl red indicator.
A sample of the acid being analyzed can be weighed using a Lunge pipette (the weighing result is recorded accurate to the fourth decimal place).
The result of the analysis is taken as the arithmetic mean of the results of two parallel determinations, the absolute discrepancy between which does not exceed the permissible discrepancy of 0.2%.
Permissible absolute total error of the analysis result is ±0.4 with confidence probability = 0,

3.4. Determination of the mass fraction of residue after calcination
The determination is carried out according to GOST 27184-86. In this case, 100 g (55 cm3) of the drug is placed in a quartz or platinum cup with a capacity of 200 cm3, previously calcined to a constant mass and weighed to the fourth digit, and evaporated to dryness in a fume hood on a sand bath or on an electric stove (power 1000-1200 W ). The cup with the dry residue is calcined in a muffle furnace at 600-800 °C to constant weight.
The preparation is considered to comply with the requirements of this standard if the mass of the residue after calcination does not exceed:
for the drug “chemically pure” - 0.6 mg (1.0* mg);
for the drug “pure for analysis” - 1.0 mg (2.0* mg);
for the drug “pure” - 5 mg.
___________
* The value indicated in brackets is set for the norm valid until 01/01/90.

If there is disagreement in assessing the quality of the analyzed acid with a mass fraction of residue after calcination of no more than 0.001%, the mass of the sample should be increased to 200 g.
The result of the analysis is taken as the arithmetic mean of the determination results, the relative discrepancy between which does not exceed the permissible discrepancy equal to 30%. The permissible relative total error of the analysis result is ±50% for a drug classified as “chemically pure” and “pure for analysis” and ±25% for a drug classified as “pure” with a confidence probability = 0.95.

3.1-3.4. (Changed edition, Amendment No. 1, 2).

3.5. Determination of the mass fraction of chlorides

3.5.1. Equipment, reagents and solutions
Flask Kn-2-250-34 THS according to GOST 25336-82.
Pipette with a capacity of 5 (10, 25) cm.
Nitric acid according to GOST 4461-77, chemically pure, solution with a mass fraction of 25%.
A solution containing Cl, mass concentration Cl 1 mg/cm, is prepared according to GOST 4212-76; By appropriate dilution with water, prepare a solution with a mass concentration of 0.01 mg/cm Cl.
Silver nitrate according to GOST 1277-75, solution with a mass fraction of 1.7%.

3.5.2. Carrying out analysis

25 g (approx. 13.75 cm) for a preparation classified as “chemically pure” and 20 g (approx. 11 cm) for a preparation “analytically pure” and “pure” are placed in a conical flask with a capacity of 250 cm (with a mark at 100 cm), containing 50 cm of water, the solution is cooled by immersing the flask in cold water with ice, then add 4 cm of nitric acid, 2 cm of silver nitrate solution, mix, bring the volume of the solution to the mark with water and mix again.
The drug is considered to comply with the requirements of this standard if the opalescence of the test solution observed after 20 minutes is not more intense than the opalescence of the reference solution prepared simultaneously with the test solution and containing in the same volume:
for the drug “chemically pure” - 0.005 mg Cl,
for the drug “pure for analysis” - 0.010 mg Cl,
for the drug “pure” - 0.020 mg Cl,

4 cm of nitric acid and 2 cm of silver nitrate solution.
In case of disagreement in the assessment of the mass fraction of chlorides in a preparation classified as “chemically pure”, the determination is carried out photometrically according to clause 3.5

3.5.1, 3.5.2. (Changed edition, Amendment No. 2).

3.5.3. Photometric method for determining the mass fraction of chlorides (standard 0.00002%)

3.5.3.1. Equipment, reagents and solutions
Flask Kn-1-500-29/32 according to GOST 25336-82.
Flask 2-100-2 according to GOST 1770-74.
Pipette with a capacity of 2 and 5 (10) cm.
Funnel VD-1-250 HS; VD-3-1000 HS according to GOST 25336-82.
Cylinder 1-100(250) according to GOST 1770-74.
Stopwatch.
Spectrophotometer type SF-16.
Cuvettes with a light-absorbing layer thickness of 10 mm.
Ultra-thermostat type U-120 or another type, allowing temperature control at a temperature of (20±1) °C.
Distilled water according to GOST 6709-72.
Dithizone according to TU 6-09-07-1684-89, analytical grade.
A solution of concentration I (CHNHNHCSN = NCH) = 1 10 mol/dm in chloroform is prepared as follows: place 0.0256 g of dithizone in a dry volumetric flask, add 80 cm of chloroform, stir until dithizone dissolves, adjust the volume of the solution with chloroform to the mark and stir;
solution II concentration (CHNHNHCSN = NCH) = 5 10 mol/dm in carbon tetrachloride is prepared as follows: 5 cm of solution I is placed in a dry volumetric flask, purified carbon tetrachloride is added to the mark and mixed; the solution is used freshly prepared; dithizone solutions are stored in dark glass vessels or in colorless glass vessels coated with black varnish.
Sodium sulfate (sodium thiosulfate) 5-water according to GOST 27068-86, analytical grade, solution with a mass fraction of 2.5%.
Chloroform according to TU 6-09-4263-76 for chromatography or according to TU 6-09-06-800-76, chemically pure. for spectroscopy.
Carbon tetrachloride according to GOST 20298-74, chemically pure, purified as follows: to 500 cm of carbon tetrachloride placed in a separating funnel (VD-3-1000), add 200 cm of sodium thiosulfate solution and shake for 5 minutes; after separation, the aqueous phase is discarded, and the carbon tetrachloride is washed 3-4 times with water, each time discarding the aqueous phase.
A solution containing Ag is prepared according to GOST 4212-76; a solution with a mass concentration of Ag of 0.02 mg/cm is prepared by appropriate dilution with water; the solution is used freshly prepared.
A solution containing Cl is prepared according to GOST 4212-76, a solution with a mass concentration of Cl of 0.01 mg/cm is prepared by appropriate dilution with water, the solution is used fresh

cooked.

3.5.3.2. Carrying out analysis
To eliminate the interfering influence of impurities found in the analyzed preparation (for example, , , , , , ), it is pre-purified with dithizone as follows.

200 g (110 cm) of the drug to be analyzed is placed in a conical flask containing 200 cm of water, the solution is cooled to room temperature by immersing the flask in cold water with ice. The solution is transferred to a separating funnel (VD-3-1000), 5 cm of a solution of dithizone in chloroform (solution I) is added and shaken for 5 minutes. After delamination, the organic layer is discarded; the solution of the analyzed drug is washed 2-3 times with purified carbon tetrachloride in 5-10 cm portions, discarding the organic layer each time.
Determination is carried out at solution temperature (20±1) °C. At higher or lower temperatures, solutions of sulfuric acid and dithizone are placed in a thermostat and kept at a temperature of (20±1) °C for 30 minutes.
Place 77 cm of purified solution of the drug into three separating funnels (corresponding to 50 g of sulfuric acid), then add 1 cm of a diluted solution containing Cl and 0.5 cm of water into the first separating funnel, and 1.5 cm of diluted solution into the second separating funnel. solution containing Cl, add 1.5 cm of water to the third separatory funnel. Then 2.5 cm of a diluted solution containing Ag is added to each funnel, the solutions are thoroughly mixed and left for 10 minutes.
Add 10 cm of dithizone II solution to the resulting solutions and shake for 5 minutes. After separation, the organic phases are placed in dry cuvettes.
The aqueous phase from the third separatory funnel is washed twice with purified carbon tetrachloride in 5 cm portions, discarding the organic layers each time.
The purified aqueous phase is used to prepare a control solution, for which 2.5 cm of a diluted solution containing Ag, 10 cm of a solution of dithizone in carbon tetrachloride (solution II) are added to the aqueous phase and shaken for 5 minutes. After liquid separation, the organic phase is placed in a dry cell.
The optical density of the resulting solutions is measured using a spectrophotometer at wavelength = (615±10) nm relative to the control

special solution.

3.5.3.3. Processing the results
The mass fraction of chlorides () as a percentage is calculated using the formulas:

where is the optical density of the first solution;
- optical density of the second solution;
- optical density of the third solution.
The result of the analysis is taken as the arithmetic mean of the results of two parallel determinations (,), the relative discrepancy between which does not exceed 40%.
The permissible relative total error of the analysis result is ±20% with confidence probability = 0.95.

3.5.3, 3.5.3.1, 3.5.3.2, 3.5.3.3. (Introduced additionally, Amendment No. 2).

3.6. Determination of the mass fraction of nitrates

3.6.1. Photocolorimetric determination With salicylic acid and sodium hydroxide

3.6.1.1. Equipment, reagents and solutions
Flask 1(2)-50(100)-2 according to GOST 1770-74.
Pipette with a capacity of 1 (2), 5 (10, 25) cm.
Distilled water according to GOST 6709-72.
Salicylic acid.
Sulfuric acid according to this standard, not containing nitrates or freshly distilled; prepare as follows; sulfuric acid is distilled in a quartz glass device, the middle fraction is selected, which does not contain iron and selenium and gives a negative reaction to chlorides and nitrates.

A solution containing NO; prepared according to GOST 4212-76; a solution with a concentration of 0.1 mg per 1 cm3 is prepared by appropriate dilution.
Photocolorimeter of any type. Cuvettes with a light-absorbing layer thickness of 20 mm.

3.6.1.2. Construction of a calibration graph
To construct a calibration curve, place 0 in volumetric flasks with a capacity of 100 cm3; 0.01; 0.03; 0.05; 0.07; 0.09; 0.11 mg of NO, add water to 5.4 cm, add 0.1 g of salicylic acid and 11 cm of nitrate-free sulfuric acid. The mixture is shaken periodically for 10 minutes. After cooling to 20 °C, the volumes of solutions are adjusted to the mark with water and mixed.
The resulting 25 cm solutions are pipetted into 50 cm volumetric flasks; carefully, while stirring, add 20 cm of sodium hydroxide solution, cool, adjust the solution volumes to the mark with water and mix. Then the optical density of the solutions relative to water is measured at a wavelength of 415 nm.
Based on the obtained optical density values, after subtracting the optical density of the control solution, a calibration graph is constructed

3.6.1.3. Carrying out analysis
Place 5.4 cm of water into a 100 cm volumetric flask, add 0.1 g of salicylic acid and 20.0 g (11 cm) of the drug being analyzed. The mixture is shaken periodically for 10 minutes. After cooling to 20 °C, the volume of the solution is adjusted to the mark with water and mixed. 25 cm of the resulting solution (corresponding to 5.0 g of the drug) is pipetted into a 50 cm volumetric flask, carefully, while stirring, 20 cm of sodium hydroxide solution is added, cooled, the volume of the solution is adjusted to the mark and mixed.
Then the optical density of the analyzed solution is measured in relation to a reference solution containing sulfuric acid (not containing nitrates) and the same volumes of solutions, at a wavelength of 415 nm.
Based on the obtained optical density values, using the calibration graph, the mass of NO in the analyzed preparation is found.
The result of the analysis is taken as the arithmetic mean of the results of two parallel determinations, the relative discrepancy between which does not exceed the permissible discrepancy equal to 50% for a drug classified as “chemically pure” and 20% for a drug classified as “pure for analysis” and “pure”.
The permissible relative total error of the analysis result is ±40% for a drug classified as “chemically pure” and ±20% for a drug classified as “pure for analysis” and “pure” with a confidence probability = 0.95.
(Changed edition, Amendment No. 2

3.6.2. Visual colorimetric determination With sodium salicylic acid and urea

3.6.2.1. Equipment, reagents and solutions
Flask 1(2)-100 according to GOST 1770-74.
Flask Kn-2-100-34 THS according to GOST 25336-82.
Pipette with a capacity of 5, 10, 25 cm.
Test tube with a capacity of 100 cm with a diameter of 18-20 mm.
Cylinder 1(3)-50 according to GOST 1770-74.
Distilled water according to GOST 6709-72.
A solution containing NO; prepared according to GOST 4212-76, a mass concentration of NO of 0.1 mg/cm is prepared by appropriate dilution.
Sodium salicylic acid, solution with a mass fraction of 10%.
Urea (urea) according to GOST 6691-77, 20% solution.
Sodium hydroxide according to GOST 4328-77, solution with a mass fraction of 20%.

3.6.2.2. Conducting analysis

7 cm of water, 2 cm of urea solution, 1 cm of sodium salicylic acid solution are placed in a volumetric flask, 40 g (about 22 cm) of the analyzed drug are added, mixed and after 5 minutes, water is carefully added while stirring. After cooling to 20 °C, the volume of the solution is adjusted to the mark with water and mixed - solution A.
Simultaneously prepare two reference solutions as follows: place a solution containing: into two volumetric flasks.
for a drug “chemically pure” for a norm of 0.00005% - 0.01 mg NO,
for the drug “pure for analysis” - 0.01 mg NO,
for the drug “pure” - 0.10 mg NO.
The volume of the solutions is adjusted to 2 cm with water, 2 cm of urea solution, 1 cm of sodium salicylic acid solution and 20 g (about 11 cm) of the analyzed drug are added.
The contents of the flasks are mixed and after 5 minutes, water is carefully added while stirring; after cooling the solutions to 20 °C, the volume is adjusted to the mark with water and solutions 1 and 2 are mixed.
To carry out the analysis, 25 cm of solution A (corresponding to 10 g of the drug), 25 cm of solution 1 (corresponding to 5 g of the drug and 0.0025 mg NO) and 25 cm of solution 2 (corresponding to 5 g of the drug and 0.025 mg NO). Carefully, while stirring, add 40 cm of sodium hydroxide solution to each flask, then the solutions are cooled to 20 °C and transferred to test tubes.
The drug is considered to comply with the requirements of this standard if the color of the analyzed drug solution, when compared along the axis of the test tube, is not more intense than the color:
solution 1 - for the drug “chemically pure” and “pure for analysis”;
solution 2 - for the “pure” drug.
Since 1/2 of a sample of the drug is introduced into the reference solutions, the calculation of the mass fraction of nitrates as a percentage is carried out for a sample of 5 g.
In case of disagreement in the assessment of the mass fraction of nitrates and when analyzing the drug at a rate of 0.00002%, the determination is carried out visually using the colorimetric method with quinalisarin

according to clause 3.6.3.

3.6.2.1, 3.6.2.2. (Changed edition, Amendment No. 2).

3.6.3. Visual colorimetric determination With quinalisarin

3.6.3.1. Equipment, reagents and solutions
Flasks 2-100-2; 2-50-2 according to GOST 1770-74.
Flask Kn-1-100-14/23 THS according to GOST 25336-82.
Pipettes with a capacity of 5 and 10 (25) cm.
Cup SV-14/8 according to GOST 25336-82.
Cylinder 1(3)-25(50) according to GOST 1770-74.
Distilled water according to GOST 6709-72.
Potassium nitrate according to GOST 4217-77.
Sulfuric acid according to GOST 4204-77, chemical grade.
Tin (II) chloride, 2-water according to TU 6-09-5393-88, solution with a mass fraction of 0.3%, is prepared as follows: 0.30 g of the drug is placed in a flask with a ground stopper, add 50 cm of water and 5 cm sulfuric acid; the contents of the flask are thoroughly mixed, the volume of the solution is adjusted to the mark with water and mixed again; the solution is good for 3 days.
1,2,5,8-tetrahydroxylantraquinone (quinalizarin), analytical grade, solution with a mass fraction of 0.035% in sulfuric acid, is prepared as follows: 0.060 g of quinalizarin is weighed in a glass and quantitatively transferred into a dry flask using several cubic centimeters of sulfuric acid. Then close the flask with a stopper, carefully mix its contents until completely dissolved, adjust the volume of the solution with sulfuric acid to the mark, close the flask with a stopper and mix.
The nitrate reagent is prepared as follows: 5 cm of quinalizarin solution, taken with a dry pipette, is placed in a dry flask, the volume of the solution is adjusted to the mark with sulfuric acid and mixed.
A solution containing NO is prepared as follows: 0.0080 g of potassium nitrate is weighed in a glass, transferred quantitatively into a flask with a solution of quinalizarin, the flask is capped and the contents are thoroughly mixed until potassium nitrate is completely dissolved, then the volume of the solution is adjusted to the mark with a solution of quinalizarin and mixed; 5 cm of the resulting solution with a mass concentration of 0.1 mg NO per 1 cm is taken using a dry pipette, placed in a dry flask 2-50-2, the volume of the solution is adjusted to the mark with sulfuric acid and mixed thoroughly; the resulting solution has a mass concentration of NO 0.01 mg/

3.6.3.2. Carrying out analysis
The determination is carried out using dry dishes.

27 cm (50 g) of the analyzed drug of the “chemically pure” and “pure for analysis” qualification and 11 cm (20 g) of the drug of the “pure” qualification, selected by volume with a cylinder with a division value of 1 cm, are placed in a dry conical flask and closed. cork. At the same time, prepare reference solutions.
Place 0.1 cm of tin (II) chloride solution into dry conical flasks, add 27 cm of the analyzed drug of the “chemically pure” and “pure for analysis” qualifications and 11 cm of the drug of the “pure” qualification, close the flasks with stoppers, the contents of the flasks mix carefully and keep at room temperature for 20 minutes.
Then, using a dry pipette, 0; 0.5; 1.0; 1.5; 2.0; 2.5 and 3.0 cm of a diluted solution containing NO mass concentration of NO 0.01 mg/cm for a drug classified as “chemically pure” and “pure for analysis” or 0.5; 1.0 and 1.5 cm of a solution containing NO with a mass concentration of NO 0.1 mg/cm for a drug qualified as “pure” are mixed and added to the same flasks 3.0; 2.5; 2.0; 1.5; 1.0; 0.5; 0 cm of nitrate reagent solution for a drug with the qualifications “chemically pure” and “pure for analysis” or 1.0; 0.5; 0 cm of a solution of quinalizarin in sulfuric acid with a mass fraction of 0.035% for a drug classified as “pure”, close the flasks with stoppers and mix.
The reference solutions should have a clear gradation in color.
Add 3 cm of a reagent solution for nitrates to the analyzed solution of a drug classified as “chemically pure” and “pure for analysis”, add 1.5 cm of a solution of quinalizarin with a mass fraction of 0.035% in sulfuric acid for a “pure” reagent, close the flasks with stoppers and mix . After 20 minutes, 0.1 cm of tin(II) chloride solution is carefully added to the analyzed solutions, the flasks are capped and mixed.
The drug is considered to comply with the requirements of this standard if, when observed against a background of milky glass in transmitted light, the blue color of the analyzed solution is not more intense than the blue color of the reference solution containing:
for the drug “chemically pure” - 0.010 mg (0.025 mg) NO;
for the drug “pure for analysis” - 0.025 mg NO;
for the “pure” preparation - 0.10 mg NO.
Permissible relative total error of the analysis result ±25% for a drug qualified “chemically pure” and “pure for analysis”, ±50% for a drug qualified “pure” with a confidence level

accuracy P = 0.95.

3.6.3-3.6.3.2. (Introduced additionally, Amendment No. 2).

3.7. Determination of the mass fraction of ammonium salts is carried out according to GOST 24245-80. At the same time, 10.0 g (5.4 cm) of the chemically pure preparation. or 5.0 g (2.7 cm) of the analytical grade drug. and parts are carefully placed in a 100 cm3 flask with a 50 cm mark containing 10 cm3 of water. The solution is cooled and neutralized (while cooling) on ​​universal indicator paper with a solution of sodium hydroxide with a mass fraction of 30%, not containing NH (prepared according to GOST 4517-87).
After cooling, the volume of the solution is adjusted to 50 cm3 with water and stirred.
Next, the determination is carried out according to GOST 24245-80.
The mass of ammonium salts should not exceed:
for the drug “chemically pure” - 0.010 mg NH,
for the drug “pure for analysis” - 0.010 mg NH,
for the “pure” drug - 0.025 mg NH.
(Changed edition, Amendment No. 1,

3.7.1, 3.7.2. (Excluded, Amendment No. 1).

3.8. Determination of the mass fraction of heavy metals

3.8.1. Thioacetamide method
The determination is carried out according to GOST 17319-76. In this case, 10 g (5.5 cm) of the drug is evaporated in a sand bath in a platinum or quartz cup up to 2 cm.
The residue is carefully transferred quantitatively into a 50 cm flask (with a 25 cm mark) containing 5 cm of water. 1 cm of potassium-sodium tartrate solution is added to the resulting solution and carefully neutralized drop by drop with an ammonia solution with a mass fraction of 25% on universal indicator paper (take-out sample). The solution is cooled, the volume is adjusted to the mark with water, and then the determination is carried out using the thioacetamide method photometrically or visually-colorimetrically.
The drug is considered to comply with the requirements of this standard if the mass of heavy metals does not exceed:
for the drug “chemically pure” - 0.01 mg,
for the drug “pure for analysis” - 0.02 mg,
for the drug “pure” - 0.05 mg.
(Changed edition, Amendment No. 2).

3.8.2. Hydrogen sulfide method
The determination is carried out according to GOST 17319-76. In this case, 20.0 g (11 cm) of the drug is evaporated in the presence of 10 mg of sodium carbonate (according to GOST 83-79) on a sand bath or electric stove in a fume hood to a volume of about 2 cm, cooled, carefully added 1 cm of nitric acid and evaporated to dryness . The residue is cooled, dissolved in 10 cm of hot water, cooled and neutralized with an ammonia solution on universal indicator paper to a slightly alkaline reaction, the volume is adjusted to 20 cm and then the determination is carried out using the hydrogen sulfide method.
The coloration of the analyzed solution observed after 10 minutes should not be more intense than the coloration of the reference solution prepared at the same time and containing in the same volume:
for the drug “chemically pure” - 0.01 mg Pb,
for the drug “pure for analysis” - 0.04 mg Pb,
for the “pure” preparation - 0.10 mg Pb and the same amounts of reagents.
In case of disagreement in the assessment of the mass fraction of heavy metals, the determination is carried out photometrically using the thioacetamide method.

3.9. Determination of the mass fraction of iron

3.9.1. Sulfosalicylic method
The determination is carried out according to GOST 10555-75. In this case, 10.0 g (5.5 cm) of the drug is placed in a porcelain, quartz or platinum cup and evaporated on an electric hot plate to approximately 2 cm. The contents of the cup are cooled and transferred quantitatively into a 50 cm flask containing 10 cm of water. Next, the determination is carried out using the sulfosalicylic method.

for the drug “chemically pure” - 0.005 mg,
for the drug “pure for analysis” - 0.010 mg,
for the drug “pure” - 0.030 mg.

3.9.2. 2,2"-dipyridyl method
The determination is carried out according to GOST 10555-75. In this case, 10.0 g (5.5 cm) of the drug is evaporated in a platinum cup to a volume of about 2 cm. The residue is cooled and transferred to a 250 cm glass containing water and carefully diluted with water to a volume of 20 cm. After cooling, the pH of the solution is adjusted with the solution ammonia up to 2 on universal indicator paper. Next, the analysis is carried out using the 2,2"-dipyridyl method.
Based on the obtained optical density values, using the calibration graph, the mass of iron in the analyzed solution is found.

3.9.1, 3.9.2. (Changed edition, Amendment No. 2).

3.9.3. 1,10-phenanthroline method
The determination is carried out according to GOST 10555-75. In this case, 10.0 g (5.5 cm) of the drug is placed in a conical flask with a capacity of 50 cm containing 10 cm of water, 1 drop of -nitrophenol solution is added (prepared according to GOST 4919.1-77), neutralized while cooling with an ammonia solution with a mass fraction of 25 % according to GOST 24127-80, special grade. 25-5, until a yellow color appears, add 5 cm of 1,10-phenanthroline solution, heat for 10 minutes in a water bath and cool. Next, the determination is carried out using the 1,10-phenanthroline method, measuring optical densities in cuvettes with a light-absorbing layer thickness of 50 mm.
The drug is considered to comply with the requirements of this standard if the mass of iron does not exceed:
for the drug “chemically pure” - 0.002 mg (0.005 mg) Fe;
for the preparation “pure for analysis” - 0.005 mg (0.010 mg) Fe;
for the “pure” preparation - 0.030 mg Fe.
It is allowed to determine the mass fraction of iron using the thiocyanate method according to GOST 10555-75 and the atomic emission spectroscopy method according to GOST 27566-87.
In case of disagreement in the assessment of the mass fraction of iron, the determination is carried out using the photometric 2,2"-dipyridyl or 1,10-phenanthroline method.
(Introduced additionally, Amendment No. 2).

3.10. Determination of the mass fraction of arsenic
The determination is carried out according to GOST 10485-75.
In this case, 10 g (5.5 cm) of the drug is carefully placed with stirring in a flask of an arsenic determination device containing 60 cm of water. Another 6 cm of the acid being analyzed is added to the resulting solution, mixed and cooled. Next, the determination is carried out using the arsine method, without adding a solution of sulfuric acid.
To determine 0.0001 mg As, glass tubes with an internal diameter of 1 mm, made of pipettes with a capacity of 0.1 cm, are used. A circle of bromide-mercury paper with a diameter of 10 mm is placed on the upper end of the tube, then a circle of filter paper with a diameter of 15-20 mm is placed and pressed tightly rubber ring.
The drug is considered to comply with the requirements of this standard if the color of bromine mercury paper from the analyzed solution is not more intense than the color of bromine mercury paper from a reference solution prepared simultaneously with the test solution under the same conditions and containing 30 cm of water:
for the drug “chemically pure” - 0.0001 mg As;
for the drug “pure for analysis” - 0.0003 mg As;
for the “pure” drug - 0.0010 mg As;

6 cm of the acid being analyzed, 0.5 cm of a solution of stannous chloride and 5 g of zinc.
It is allowed to carry out the determination using the method using silver diethyldithiocarbamate.
In case of disagreement in the assessment of the mass fraction of arsenic, the determination is carried out using the arsine method

3.8-3.10. (Changed edition, Amendment No. 1).

3.11. Determination of the mass fraction of selenium

3.11.1. Equipment, reagents and solutions
Flask Kn-2-50-18 THS according to GOST 25336-82.
Pipette with a capacity of 5 (10) cm.
Distilled water according to GOST 6709-72.
Hydrazine sulfate according to GOST 5841-74, solution with a mass fraction of 2%, prepared according to GOST 4517-87.
Hydrochloric acid according to GOST 3118-77, chemical grade.
A solution containing Se is prepared according to GOST 4212-76; a solution of selenium mass concentration of 0.01 mg/cm is prepared by appropriate dilution.
(Changed edition, Amendment No. 2).

3.11.2. Carrying out analysis

10 g (about 5.5 cm) of the drug are carefully placed in a flask containing 10 cm of water, mixed and cooled. Then 1 cm of hydrochloric acid and 5 cm of hydrazine sulfate solution are added to the solution, the solution is heated to boiling and kept at 80 °C for 10 minutes.
The drug is considered to comply with the requirements of this standard if the color of the analyzed solution observed after 10 minutes is not more intense than the color of the solution prepared simultaneously with the analyzed solution and containing in the same volume:
for the drug “chemically pure” - 0.01 mg Se,
for the drug “pure for analysis” - 0.01 mg Se,
for the “pure” drug - 0.005 mg Se,

1 cm of hydrochloric acid and 5 cm of hydrazine sulfate solution.

3.12. Determination of the mass fraction of substances that reduce KMnO in the form of SO

3.12.1. Equipment, reagents and solutions
Burette with a capacity of 1 cm with a division value of 0.01 cm; capacity 2 cm with division price 0.02 cm; capacity 1 (2) cm with division value 0.01 cm; with a capacity of 5 cm with a division value of 0.02 cm.
Pipette with a capacity of 25 cm.
Distilled water according to GOST 6709-72.
Potassium permanganate according to GOST 20490-75, concentration solution (1/5 KMnO) = 0.01 mol/dm (0.01 N), freshly prepared; prepared according to GOST 25794

3.12.2. Carrying out analysis

20 g (about 11 cm) of the drug is carefully added to 60 cm of water while stirring. The solution is cooled to 20 °C and a solution of potassium permanganate is added dropwise from a burette:
for the drug “chemically pure” - 0.13 (0.20) cm,
for the preparation “pure for analysis” - 0.20 cm,
for the “pure” preparation - 0.26 cm.
The product is considered to comply with the requirements of this standard if the observed pink color of the test solution does not disappear within 5 min.
A control experiment is carried out simultaneously with the analysis.

3.11.2-3.12.2. (Changed edition, Amendment No. 1, 2).

3.13. Sawall's test

3.13.1. Equipment, reagents and solutions
Flask Gr-50-14/23 THS according to GOST 25336-82.
Pipette with a capacity of 10 cm.
Rectified technical ethyl alcohol according to GOST 18300-87 of the highest grade.

3.13.2. Carrying out analysis
10 cm of alcohol is placed in a flask with a capacity of 40-50 cm, with a neck length of 80-100 mm.
In 3-4 doses, with constant stirring, 10 cm of the acid being analyzed is added to the flask with alcohol along the wall of the flask. Without interrupting shaking, the flask with its contents is introduced into the upper part of the flame of an alcohol burner having a flame height of 40-50 mm and heated until bubbles appear, forming a light foam on the surface of the liquid (usually this takes 30-45 s) .
After cooling, the liquid is compared with the same volume of alcohol in the same flask.
The drug is considered to comply with the requirements of this standard if, after cooling, the liquid in the flask remains colorless.
Three parallel determinations are carried out simultaneously.

3.13.1, 3.13.2. (Changed edition, Amendment No. 2).

4. PACKAGING, LABELING, TRANSPORTATION AND STORAGE

4.1. The drug is packaged, sealed and labeled in accordance with GOST 3885-73. Volume dosage of the drug is allowed.
The acid density (1.83 g/cm) should be indicated on the label.
Type and type of container: 3-1, 3-6, 8-1, 8-3, 3-8, 3-11, 8-2, 8-5, 10-1.
Packing group: V, VI, VII (no more than 30 dm).
A fabric napkin is placed on the neck of the container (3-1 and 8-1), tied with hemp twine, vinyl chloride thread or other strong thread, then plaster is applied. Instead of plastering, it is allowed to apply polyethylene film in two layers followed by tying.
Consumer packaging is packaged in metal, polymer or wooden boxes or containers. If there are no fixing elements in the transport container, the gap between the consumer and transport containers is filled with indifferent material.
To pack containers with sulfuric acid, use wood shavings impregnated with solutions of calcium chloride, magnesium chloride or ammonium sulfate, as well as slag wool or other non-flammable sealing material.
The containers are marked with danger signs in accordance with GOST 19433-88 (class 8, subclass 8.1, drawing 8, classification code 8112) and UN serial number 1830.
(Changed edition, Amendment No. 1, 2).

4.2. The drug is transported by all modes of transport in accordance with the cargo transportation rules in force for this type of transport.

4.3. The drug is stored in the manufacturer's packaging in covered warehouses.

5. MANUFACTURER WARRANTY

5.1. The manufacturer guarantees that sulfuric acid meets the requirements of this standard subject to the conditions of transportation and storage.

5.2. The guaranteed shelf life of the product is three years from the date of manufacture.

5.1, 5.2. (Changed edition, Amendment No. 1).

6. SAFETY REQUIREMENTS

6.1. Sulfuric acid and its vapors have a strong cauterizing and irritating effect on mucous membranes.
If it comes into contact with the skin and mucous membranes, sulfuric acid causes severe burns.

6.2. When working with the drug, it is necessary to strictly observe measures to prevent the release of sulfuric anhydride into the air, contact of sulfuric acid on the skin, use personal protective equipment (long-sleeved gowns in accordance with GOST 12.4.131-83, respirators, goggles, rubber gloves, oversleeves, rubber aprons), and also observe personal hygiene measures.

6.3. The maximum permissible concentration of sulfuric acid and sulfuric anhydride in the air of the working area of ​​industrial premises is 1 mg/m. When the maximum permissible concentration is exceeded, sulfuric acid vapors irritate and cauterize the mucous membranes of the upper respiratory tract and affect the lungs. Hazard class 2 according to GOST 12.1.005-88.
(Changed edition, Amendment No. 2).

6.4. Premises in which work with sulfuric acid is carried out must be equipped with general supply and exhaust mechanical ventilation. The analysis of the drug must be carried out in a laboratory fume hood.

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STATE STANDARD

REAGENTS

SULFURIC ACID

TECHNICAL CONDITIONS

Official publication

UDC 546.226-325-41: 006.354

Group L51

INTERSTATE STANDARD

Reagents SULFURIC ACID Technical conditions

Reagents. Sulfuric acid. Specifications

MKS 71.040.30 OKP 26 1212 0021 05

Date of introduction 07/01/78

This standard applies to the reagent - sulfuric acid, which is a colorless, transparent, oily liquid, odorless, without sediment, miscible with water (with strong heating) and with alcohol.

Formula H2SO4.

Molecular mass (according to international atomic masses 1971) - 98.08.

The density of okaya is 1.83 g/cm 3 .

(Changed edition. Amendment No. 1, 2).

1. TECHNICAL REQUIREMENTS 1

1.3. Sulfuric acid of the “chemically pure 1” and “pure for analysis” qualification, intended for the analysis of ethyl alcohol, must withstand the Savall test but also. 3.13.

1.4. Sulfuric acid is permitted in other concentrations provided that the other requirements of this standard are met.

1.5. The manufacturer is allowed to periodically determine (once a month) the mass fraction of chlorides, nitrates, heavy metals, arsenic and selenium in sulfuric acid made from natural and gas sulfur (according to GOST 127.1 - 127.5).

1.4, 1.5. (Introduced additionally, Amendment No. 2).

2. ACCEPTANCE RULES

2.2. Samples from large-sized containers (tanks, containers), used by agreement between the manufacturer and the consumer, are taken with a sampler made of fluoroplastic.

(Introduced additionally, Amendment No. 2).

3. METHODS OF ANALYSIS

3.1a. General instructions for conducting analysis - but GOST 27025.

When weighing, use general purpose laboratory scales such as VLR-200 g and VLKT-500g-M or VLE-200 g.

It is allowed to use other measuring instruments with metrological characteristics and equipment with technical characteristics no worse, as well as reagents of quality no lower than those specified in this standard.

(Changed edition, Amendment No. 2).

The total mass of the average sample must be at least 1.5 kg (800 cm 3).

The volume fraction of sulfuric acid required for analysis is taken with a safe pipette or measuring cylinder with an error of no more than 1%.

(Changed edition, Rev. No. |, 2).

3.2. Definition of appearance

The drug is considered to comply with the requirements of this standard if the analyzed drug, observed against the background of milk glass in transmitted light, does not differ from distilled water.

3.3. Determination of the mass fraction of sulfuric acid

3.3.1. Equipment, reagents and solutions

Burette with a capacity of 50 cm 3 with a division foam of 0.1 cm 3.

Flask Kn-2-500-40 THS or Kn-1-500-29/32 THS according to GOST 25336.

Methyl red (indicator) according to TU 6-09-5169, solution with a mass fraction of 0.1%. prepared according to GOST 4919.1.

Methyl orange (indicator) according to TU 6-09-5171. solution with a mass fraction of 0.1%. prepared according to GOST 4919.1.

Mixed indicator, methyl red and methylene blue; prepared according to GOST 4919.1.

3.3.2. Carrying out a on. I and for

About 1.0000 g of the drug is weighed in a sealed ampoule (the weighing result in grams is recorded accurate to the fourth decimal place), then the ampoule is placed in a flask containing 200 cm 3 of water. The ampoule is broken with a glass rod with a flat end and the contents of the flask are mixed. Add 5 drops of a mixed indicator to the solution and titrate with sodium hydroxide solution until it turns green.

3.3.3. Processing the results

The mass fraction of sulfuric acid in percent (L") is calculated using the formula

x= V 0.04904 100 t

where V is the volume of sodium hydroxide solution of concentration exactly with (NaON) = 1 mol/dm 3 (1 n). spent on titration of the analyzed drug, cm 3 ;

0.04904 is the mass of sulfuric acid corresponding to 1.00 cm 3 of sodium hydroxide solution with a concentration of exactly (NaOH) = 1 mol/dm 3 (1 n). G;

t is the mass of a sample of the analyzed drug, g.

It is allowed to determine mass dates and sulfuric acid in the presence of a methyl orange or methyl red indicator.

A sample of the acid being analyzed can be weighed using a Lunge pipette (the weighing result is recorded accurate to the fourth decimal place).

The result of the analysis is taken as the arithmetic mean of the results of two parallel determinations, the absolute discrepancy between which does not exceed the permissible discrepancy of 0.2%.

The permissible absolute total error of the analysis result is ± 0.4 with a confidence probability of P = 0.95.

3.4. Determination of the mass fraction of residue after calcination

Pipette with a capacity of 5 (10.25) cm 3.

The drug is considered to comply with the requirements of this standard if the opalescence of the analyzed solution observed after 20 minutes is not more intense than the opalescence of the solution; comparison, prepared simultaneously with the analyzed one and containing in the same volume:

for a “chemically pure” drug - 0.005 mg CI.

for the drug “pure for analysis” - 0.010 mg CI.

for the “pure” drug - 0.020 mg CI.

4 cm 3 of nitric acid and 2 cm 3 of silver nitrate solution.

In case of disagreement in the assessment of the mass fraction of chlorides in a preparation classified as “chemically pure”, the determination is carried out photometrically according to clause 3.5.3.

3.5.1. 3.5.2. (Changed edition. Amendment No. 2).

3.5.3. Photometric method for determining the mass share of legal entities (according to the norm of 0.00002%)

3.5.3.1. Equipment, reagents and solutions

Pipette with a capacity of 2 and 5 (10) cm 3.

Funnel VD-1-250 HS; VD-3-1000 HS according to GOST 25336.

Stopwatch.

Spectrophotometer type SF-16.

Cuvettes with a light-absorbing thickness of 10 mm.

Ultra-thermostat type U-120 or other type, allowing thermostatting at a temperature of (20 ± I) * C.

Dithizone according to TU 6-09-07-1684. h.d.a.

A solution of concentration I with (C^H^NHNHCSN = NC 6 H S) = 1 10 _3 mol/dm 3 in chloroform is prepared as follows: 0.0256 g of dithizone is placed in a dry volumetric flask, 80 cm 3 of chloroform is added, and stirred until dithizone dissolves. bring the volume of the solution to the mark with chloroform and mix;

solution II of concentration c(C^HjNHNHCSN = N0.4$) = 5 10 -5 mol/dm 3 in carbon tetrachloride is prepared as follows: 5 cm 3 of solution I is placed in a dry volumetric flask, purified carbon tetrachloride is added to the mark and mixed; the solution is used freshly prepared; dithizone solutions are stored in dark glass vessels or in colorless glass vessels coated with black varnish.

Sodium sulfate (sodium thiosulfate) 5-water according to GOST 27068. h.d.a. solution with a mass fraction of 2.5%.

Chloroform according to TU 6-09-4263 for chromatography or according to TU 6-09-06-800. x. hours for spectroscopy.

Carbon tetrachloride according to GOST 20298. X. h. purified as follows: to 500 cm 3 of carbon tetrachloride placed in a separating funnel (VD-3-1000), add 200 cm 3 of sodium thiosulfate solution and shake for 5 minutes: after separation, the aqueous phase is discarded. and carbon tetrachloride is washed 3-4 times with water, each time discarding the aqueous phase.

3.5.3.2. Carrying out analysis

To eliminate the interfering influence of impurities found in the analyzed preparation (for example Bi 3 *. Co 2 *. Cd 2 *. Ni 2 *. Fe 2 *. Pb 2 ~). carry out preliminary cleaning with dithizone as follows.

200 g (110 cm 3) of the analyzed drug is placed in a conical flask containing 200 cm 3 of water, the solution is cooled to room temperature by pouring the flask into cold water with ice. The solution is transferred to a separating funnel (VD-3-1000), 5 cm 3 of a solution of dithizone in chloroform (solution I) is added and shaken for 5 minutes. After separation, the organic layer is discarded, the solution of the analyzed drug is washed 2-3 times with purified carbon tetrachloride in portions of 5-10 cm 3, each time discarding the organic layer.

The determination is carried out at the temperature of the solutions (20 ± 1) * C. At higher or lower temperatures, solutions of sulfuric acid and dithizone are placed in a thermostat and kept at a temperature of (20 ± 1) °C for 30 minutes.

Add 77 cm 3 of purified solution of the drug into three separating funnels (corresponding to 50 g of sulfuric acid), then add 1 cm 3 of a diluted solution containing CI and 0.5 cm 3 of water to the first separating funnel, and 1.5 cm 3 of diluted water into the second separating funnel. solution containing CI. 1.5 cm 3 of water is added to the third separating funnel. Then 2.5 cm 3 of a diluted solution containing Ag is added to each funnel, the solutions are thoroughly mixed and left for 10 minutes.

Add 10 cm 3 of dithizone II solution to the resulting solutions and shake for 5 minutes. After separation, the organic phases are placed in dry cuvettes.

The aqueous phase from the third separatory funnel is washed twice with purified carbon tetrachloride in 5 cm 3 portions, discarding the organic layers each time.

The purified aqueous phase is used to prepare a control solution, for which 2.5 cm 3 of a dilute solution containing Ag is added to the aqueous phase, 10 cm 3 solution;! dithizone in carbon tetrachloride (solution;! II) and shake for 5 minutes. After liquid separation, the organic phase is placed in a dry cell.

The optical density of the resulting solutions is measured using a spectrophotometer at wavelength X = (615 ± 10) nm in relation to the control solution.

3.5.3.3. Processing the results

The mass fraction of chlorides (L) as a percentage is calculated using the formulas:

0.010 £>3 100

X[ = (2), - 0,) 50 1000 ;

0,015 0, 100 * 2 = <0, - D y) 50 1000 *

where /)| - optical density of the first solution;

/>2 is the optical density of the second solution;

Dy is the optical density of the third solution.

The result of the analysis is taken as the arithmetic mean of the results of two parallel determinations (ATj. Aj), the relative discrepancy between which does not exceed 40%.

The permissible relative total error of the analysis result is ± 20% with a confidence level of P = 0.95.

3.5.3. 3.5.3.1. 3.5.3.2. 3.5.3.3. (Introduced additionally, Amendment No. 2).

3.6. Determination of the mass fraction of nitrates

3.6.1. Photocolorimetric determination with salicylic acid and sodium hydroxide

3.6.1.1. Equipment, reagents and solutions

Pipette capacity I (2). 5 (10.25) cm 3.

Salicylic acid.

Sulfuric acid according to this standard, not containing nitrates or freshly distilled; is prepared as follows: sulfuric acid is distilled in a quartz glass device, the middle fraction is selected, which does not contain iron and selenium and gives a negative reaction to chlorides and nitrates.

Pipette with a capacity of 5, 10. 25 cm 3.

Test tube with a capacity of 100 cm 3 with a diameter of 18-20 mm.

Sodium salicylic acid, solution with a mass fraction of 10%.

To carry out the analysis, 25 cm 3 of solution A (corresponding to 10 g of the drug), 25 cm 3 of solution 1 (corresponding to 5 g of the drug and 0.0025 mg N0 3) and 25 cm 3 of solution 2 (corresponding to 5 g of the drug and 0.025 mg N0 3). Be careful when stirring. add 40 cm 3 of sodium hydroxide solution to each flask, then the solutions are cooled to 20 * C and transferred to test tubes.

The drug is considered to comply with the requirements of this standard if the color of the analyzed drug solution, when compared along the axis of the test tube, is not more intense than the color:

solution;! I - for the drug “chemically pure” and “pure for analysis”;

solution 2 - for the “pure” preparation.

Since 1/2 of a sample of the drug is introduced into the reference solutions, the calculation of the mass fraction of nitrates as a percentage is carried out for a sample of 5 g.

In case of disagreement in the assessment of the mass fraction of nitrates and when analyzing the drug at a rate of 0.00002%, the determination is carried out visually using the calorimetric method with quinalizarin according to i. 3.6.3.

3.6.2.1. 3.6.2.2. (Changed edition, Amendment No. 2).

3.6.3. Visual!no-legal-metric determination with quinashzarin

3.6.3.1. Equipment, reagents and solutions

Pipettes with a capacity of 5 and 10 (25) cm 3.

Tin(II) chloride. 2-water according to TU 6-09-5393. solution with a mass distance of 0.3%. prepare as follows: 0.30 g of the drug is placed in a flask with a ground stopper, 50 cm 3 of oxen and 5 cm 3 of sulfuric acid are added; the contents of the flask are thoroughly mixed, the volume of the solution is adjusted to the mark with water and mixed again; the solution is good for 3 days.

1.2.5,8-tetrahydroxylanthraquinone (quinali sarin). analytical grade, a solution with a mass concentration of 0.035% in sulfuric acid, is prepared as follows: 0.060 g of khinali zari is weighed in a glass and quantitatively transferred into a dry flask using several cubic centimeters of sulfuric acid. Then close the flask with a stopper, carefully mix its contents until completely dissolved, adjust the volume of the solution with sulfuric acid to the mark, close the flask with a stopper and mix.

The nitrate reagent is prepared as follows: 5 cm 3 of quinalizarin solution. selected with a dry pipette, place in a dry flask, adjust the volume of the solution with sulfuric acid to the mark and mix.

A solution containing NO3. prepared as follows: 0.0080 g of potassium nitrate is weighed in a glass, transferred quantitatively into a flask with a solution of quinalizarin, the flask is closed with a stopper and the contents are thoroughly mixed until potassium nitrate is completely dissolved, then the volume of the solution is adjusted to the mark with a solution of quinalizarin and mixed; 5 cm 3 of the resulting solution with a mass concentration of 0.1 mg NO3 in I cm 3 is taken using a dry pipette, placed in a dry flask 2-50-2, the volume of the solution is adjusted to the mark with sulfuric acid and thoroughly mixed: the resulting solution has a mass concentration of NO 3 0.01 mi /cm 3.

3.6.3.2. Carrying out analysis

The determination is carried out using dry dishes.

27 cm 3 (50 g) of the analyzed drug of the “chemically pure* and “pure for analysis” qualification and 11 cm 3 (20 g) of the drug of the “pure” qualification, selected by volume with a cylinder with a division value of 1 cm 3, are placed in a dry conical flask , close it with a stopper. At the same time, prepare reference solutions.

Place 0.1 cm 3 of a solution of tin (II) chloride into dry conical flasks, add 27 cm 3 of the analyzed drug of the “chemically pure” and “clean for analysis” qualification and 11 cm 3 of the drug of the “pure” qualification, close the flasks with stoppers, contents The flasks are stirred carefully and kept at room temperature for 20 minutes.

Then, using a dry pipette, 0; 0.5; 1.0; 1.5; 2.0; 2.5 and 3.0 cm 3 of a diluted solution containing NO3 mass concentration N0 3 0.01 mg/cm 3 for a drug qualified “chemically pure” and “pure for analysis” or 0.5; 1.0 and 1.5 cm 3 of a solution containing NO3 with a mass concentration of NO3 of 0.1 mg/cm 3 for a preparation classified as “pure”.

mix, add to the same flasks 3.0; 2.5; 2.0; 1.5; 1.0; 0.5; 0 cm 3 of nitrate reagent solution for a drug with qualifications “chemically pure” and “pure for analysis” or 1.0; 0.5; 0 cm 3 of a solution of quinalizarin in sulfuric acid with a mass fraction of 0.035% for a drug classified as “pure”, close the flasks with stoppers and mix.

Comparison solutions should have a clear gradation in color.

Add 3 cm 3 of a reagent solution for nitrates to the analyzed solution of a drug classified as “chemically pure” and “pure for analysis”, add 1.5 cm 3 of a solution of quinalizarin with a mass fraction of 0.035% in sulfuric acid for a reagent qualified as “pure”, close the flasks with stoppers and mix . After 20 minutes, 0.1 cm 3 of tin (II) chloride is carefully added to the analyzed solutions. close the flasks with stoppers and mix.

The drug is considered to comply with the requirements of this standard if, when observed against the background of milky glass in transmitted light, the blue color of the analyzed solution will not be more intense than the blue color of the reference solution containing:

for the drug “chemically pure” - 0.010 mg (0.025 mg) N0 3; for the drug “pure for analysis” - 0.025 mg N0 3; for the “pure” drug - 0.10 mg N0 3.

The permissible relative total error of the analysis result is ± 25% for a drug classified as “chemically pure” and “pure for analysis”, ± 50% for a drug classified as “pure” with a confidence level of P = 0.95.

3.6.3-3.6.3.2. (Introduced additionally. Amendment No. 2).

3.7. The mass fraction of ammonium salts is determined according to GOST 24245. In this case, 10.0 g (5.4 cm 3) of drug x. tsp or 5.0 g (2.7 cm 3) of the drug, analytical grade. and h. placed carefully in a flask with a capacity of 100 cm 3 with a mark of 50 cm 3 containing 10 cm 3 of water. The solution is cooled and neutralized (while cooling) on ​​universal indicator paper with a solution of sodium pyrooxide with a mass concentration of 30%. not containing NH 4 (prepared according to GOST 4517).

After cooling, the volume of the solution is brought to 50 cm 3 with water and mixed.

The mass of ammonium salts should not exceed: for a “chemically pure” preparation - 0.010 mg NH 4. for the preparation “pure for analysis” - 0.010 mg NH 4, for the preparation “pure” - 0.025 mg NH 4.

(Changed edition. Changes No. 1,2).

3.7.1. 3.7.2. (Excluded. Amendment No. I).

3.8. Determination of the mass fraction of heavy metals

3.8.1. Thioacetamide methec)

for the drug “chemically pure” - 0.01 mg Pb.

for the drug “pure for analysis” - 0.04 mg Pb,

for the “pure*” preparation - 0.10 mg Pb and the same amount of reagents.

In case of disagreement in the assessment of the mass fraction of heavy metals, the determination is carried out photometrically using the thioacetamide method.

3.9 Determination of the mass fraction of iron

3.9.1. Sulfosaic method

In case of disagreement in the assessment of the mass fraction of iron, the determination is carried out using the photometric 2.2"-dipyridyl or 1.10-fsnanthroline method.

(Introduced additionally. Amendment No. 2).

3.10. Determination of the mass fraction of arsenic Determination is carried out according to GOST 10485.

In this case, 10 g (5.5 cm 3) of the drug is carefully placed with stirring into the flask of a device for determining arsenic, containing 60 cm 3 of water. Another 6 cm 3 of the acid being analyzed is added to the resulting solution, mixed and cooled. The determination is carried out using the arsine method, without adding a solution of sulfuric acid.

To determine 0.0001 mg As, glass tubes with an internal diameter of 1 mm are used. made from pipettes with a capacity of 0.1 cm 3 . A circle of bromide-mercury paper with a diameter of 10 mm is placed on the upper end of the tube. then a circle of filter paper with a diameter of 15-20 mm and press them tightly with a rubber ring.

The drug is considered to comply with the requirements of this standard if the color of the bromine-mercury paper from the analyzed solution is not more intense than the color of the bromine-mercury paper from the reference solution prepared simultaneously with the test solution under the same conditions and containing 30 cm 3 of water:

© Standards Publishing House. 1977

© STANDARDINFORM. 2006 © STANDARDINFORM. 2008