GOST 12348-78

• gost-12348-78.pdf (569.21 KiB)
  ГОСТ 12348-78

GOST 12348−78 (ST SEV 486−88, ISO 629−82) Steel alloyed and high alloy. Methods for determination of manganese (with Amendments No. 1, 2, 3)

GOST 12348−78
(ISO 629−82)

Group B39

INTERSTATE STANDARD

STEEL ALLOYED AND HIGH-ALLOYED

Methods for determination of manganese

Alloyed and high-alloyed steels. Methods of manganese determination

ISS 77.080.20
AXTU 0809

Date of introduction 1980−01−01

Resolution of the USSR State Committee for standards of 23 November 1978 N 3081 date of establishment established with 01.01.80

Limitation of actions taken by Protocol No. 4−93 of the Interstate Council for standardization, Metrology and certification (ICS 4−94)

REPLACE GOST 12348−66, in addition to General guidance

EDITION (may 2011) with Amendments No. 1, 2, 3, approved in August 1980, August 1984, October 1989 (IUS sizes 11−80, 11−84, 1−90)


This standard specifies the methods for determination of manganese:

When the photometric mass fraction of manganese from 0.005 to 10.0%;

Titrimetric (arsenite-nitrite) when the mass fraction of manganese from 0.30 to 10.0%;

When the potentiometric mass fraction of manganese from 4.0 to 40.0%;

Atomic absorption when the mass fraction of manganese from 0.01 to 5.0%.

The standard fully complies ST SEV 486−88, ISO 629−82.

(Changed edition, Rev. N 1, 3).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 20560−81*.
________________
* From 1 July 1991 replaced by GOST 28473−90.

2. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF MANGANESE (0,05−10,0%)

2. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF MANGANESE (0,005−10,0%)

2.1. The essence of the method

The method is based on oxidation of manganese ions (II) at a concentration in the solution in the range of 0.001−0.012 mg/ml in sulfate medium (1,0−3,5); hodnoceni potassium to manganese acid and measuring the optical density of the colored solution at a wavelength of 535−545 nm.

(Changed edition, Rev. N 3).

2.2. Apparatus, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

Hydrochloric acid by the GOST 3118−77.

Nitric acid GOST 4461−77 or GOST 11125−84 and diluted 1:1, 1:100.

Sulfuric acid GOST 4204−77 or GOST 14262−78 and diluted 1:4.

Orthophosphoric acid according to GOST 6552−80.

A mixture of sulphuric and phosphoric acids: 750 cmwater gently with continuous stirring poured 150 cmof sulfuric acid, cooled, poured 100 cmof phosphoric acid, stirred and cooled.

Potassium or sodium cognately, 5% solution: 50 g jednolitego potassium are dissolved in 800 cmof nitric acid 1:1, the solution was cooled, top up with water to 1 DMand stirred.

Potassium permanganate according to GOST 20490−75.

Hydrogen peroxide according to GOST 10929−76, 30% solution.

Carbonyl iron is particularly clean.

Manganese sulphate, standard solutions A and B.

Solution A. 0,5754 g of potassium permanganate, recrystallized and dried in air, placed in a beaker with a capacity of 300 cm, add 20 cmsulphuric acid 1:4 and carefully, drop by drop, while stirring, pour the hydrogen peroxide or hydrochloric acid to the bleaching solution. The solution was evaporated until beginning crystallization. The residue is dissolved in 20−30 cmof water, cooled, transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

1 cmstandard solution contains 0.0002 g of manganese.

Solution B. 100 cmstandard solution And placed in a volumetric flask with a capacity of 200 cm, is diluted to the mark with water and mix.

1 cmstandard solution B contains 0.0001 g of manganese.

Solution B. 50 cmof a solution transferred to a volumetric flask with a capacity of 250 cm, made up to the mark with water and mix.

1 cmstandard solution contains 0.02 mg of manganese.

The solution is prepared before use.

Water that does not contain reducing agents. In a flask with a capacity of 1.5−2 DM1 DM pouredwater, poured dropwise sulfuric acid to pH 3 by universal indicator paper, heated to boiling, add a few crystals of potassium Odnokolenko, boil for 5−7 min and cool. Water, not containing reducing agents, is used for dilution of the oxidized solutions, prepared for the photometry.

2.3. Analysis

The weight of steel depending on the mass fraction of manganese (table.1) is placed in a beaker with a capacity of 250−300 cm, 30 cm, pour themixture of sulphuric and phosphoric acids, the beaker cover watch glass, and heated for 5−10 minutes Then gently pour the 10 cmof nitric acid and heated until complete dissolution of the sample.

Table 1

If the carbides are not decomposed, by removing and washing the glass, the solution was evaporated to fumes of sulfuric acid, carefully, on the side of a glass, add a few drops of nitric acid and again evaporated to fumes of sulfuric acid.

Insoluble under these conditions, steel can be dissolved in hydrochloric acid or in a mixture of hydrochloric and nitric acids. Then the solution was poured 30 cmof a mixture of sulfuric and phosphoric acid, it is evaporated until fumes of sulphuric acid and cooled. Wash the side of the Cup with water and again evaporate the solution to fumes of sulfuric acid.

The contents of the Cup cool, dissolve salt in 50−60 cmof water and filtered off the precipitate of silicic acid to the filter «white ribbon», collecting the filtrate and wash liquid in a volumetric flask with a capacity of 250 cmfor the mass concentration of manganese in excess of 0.05% or volumetric flask with a capacity of 100 cmwhen the mass fraction of manganese from 0.005 to 0.05%. The glass and the filter cake was washed 3−5 times with nitric acid 1:100. Filter the precipitate discarded. The contents of the flask are cooled, made up to the mark with water and mix.

Aliquot part (tab.1) solution placed in a conical flask with a capacity of 250 cm, pour water to about 50 cm, 25 cmof a mixture of sulfuric and phosphoric acids and 10 cmof a solution of potassium jednolitego.

The contents of the flask heated to boiling, boiled for 1 min and left in a water bath at a temperature of approximately 90 °C for 40−50 min. Then solution was cooled, transferred to a volumetric flask with a capacity of 100 cm, top up with water containing no reducing agents to the mark and mix.

Optical density of the solution measured on a spectrophotometer at a wavelength of 545 nm or photoelectrocolorimeter with a filter having a region of transmittance in the wavelength range of 530−550 nm in a cuvette with a thickness of the absorbing layer is 20 mm.

For solution preparation comparison aliquot part of the solution placed in a conical flask with a capacity of 250 cm, pour water to about 70 cm, 2−3 drops of hydrochloric acid, heated to boiling, boil for 2−3 min, cooled, transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix. A lot of manganese in milligrams find the calibration schedule subject to amendments the reference experiment.

2.2.; 2.3. (Changed edition, Rev. N 2, 3).

2.3.1. Construction of calibration curve

When the mass fraction of manganese over 0.05%.

2 g of carbonyl iron is placed in a beaker with a capacity of 250−300 cm, flow 50 cmof a mixture of sulfuric and phosphoric acid and heated to dissolve the iron. The solution is oxidized by adding dropwise nitric acid, boil to remove oxides of nitrogen and cooled. The solution was transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

10 cmresulting solution was placed in eight conical flasks with a capacity of 250 cm, to the seven flasks is added consistently 1, 2, 4, 6, 8, 10 and 12 cmstandard solution B of manganese sulphate, which corresponds to 0,1; 0,2; 0,4; 0,6; 0,8; 1,0; 1,2 mg of manganese. In the eighth flask conduct control experience on the content of manganese in the reagents.

The solution in each flask and top up with water to about 50 cm, is added to 25 cmof a mixture of sulfuric and phosphoric acids, and 10 cmof a solution of potassium jednolitego. The contents of the flask heated to boiling, boiled for 1 min and left to stand at a temperature of approximately 90 °C for 40−50 min.

When the mass fraction of manganese from 0.005 to 0.05% in seven glasses with a capacity of 250−300 cmis placed 2 g of carbonyl iron, poured at 50 cmof a mixture of sulfuric and phosphoric acid and heated to dissolve the iron. The solution is oxidized by adding dropwise nitric acid, boil to remove oxides of nitrogen and cooled. The solutions were transferred to volumetric flasks with a capacity of 100 cm, made up to the mark with water and mix.

Seven flasks with a capacity of 250 cmis placed 40 cmof the resulting solution of iron and six of them add 1,0; 2,0; 5,0; 10,0 and 20,0 cmstandard solution, which corresponds to 0,02; 0,04; 0,10; 0,20 and 0,40 mg of manganese.

The solution in each flask and top up with water to about 50 cm, add 5 cmof a mixture of sulfuric and phosphoric acids, and 10 cmjednolitego potassium. The solutions were heated to boiling, boil for 1−2 minutes and leave it for 40−50 minutes at a temperature of 90 °C. the Solution in the seventh flask is used for the reference experiment and a solution of comparison.

The solutions were cooled, transferred to volumetric flasks with a capacity of 100 cm, top up with water containing no reducing agents to the mark and mix. The optical density of solutions measured on spectrophometer at a wavelength of 545 nm or photoelectrocolorimeter with a filter having a region of transmittance in the wavelength range of 530−550 nm in a cuvette with a thickness of the absorbing layer is 20 mm. as a solution comparison solution is used in the control tests.

The found values of optical density and corresponding masses of manganese build the calibration graph.

(Changed edition, Rev. N 1, 2, 3).

2.4. Processing of the results

2.4.1. Mass fraction of manganese () in percent is calculated by the formula

,

where is the weight of steel, suitable fotometricheskoe aliquote part of the solution, mg;

 — weight of manganese, was found in the calibration schedule, mg.

(Changed edition, Rev. N 2).

2.4.2. Permissible absolute discrepancy between the outermost of the three parallel results at a confidence level should not exceed the values given in table.2.

Table 2

(Changed edition, Rev. N 3).

3. TITRIMETRIC METHOD FOR THE DETERMINATION OF MANGANESE (0,3−10%) IN THE STEELS CONTAINING NO COBALT

3.1. Determination of manganese in steels containing up to 1% chromium

3.1.1. The essence of the method

The method is based on oxidation of manganese ions (II) neccersarily ammonium manganese to the acid in an acidic medium in the presence of silver nitrate. Ions octarepeat solution arsenit-sodium nitrite.

3.1.2. Reagents and solutions

Nitric acid GOST 4461−77.

Sulfuric acid GOST 4204−77 and diluted 1:4.

Orthophosphoric acid according to GOST 6552−80.

A mixture of acids: 550 cmof water gently, with continuous stirring, pour the 90 cmof sulfuric acid, cooled, poured 100 cmof phosphoric acid, stirred and poured 260 cmof nitric acid.

Universal indicator paper.

Neccersarily ammonium (ammonium persulfate) according to GOST 20478−75, 20% solution.

Silver nitrate according to GOST 1277−75, a 0.5% solution.

Sodium chloride according to GOST 4233−77, 0,2% solution.

Arsenic anhydride according to GOST 1973−77.

Sodium mistakemistake ortho ().

Sodium bicarbonate according to GOST 4201−79.

Sodium hydroxide according to GOST 4328−77, a 15% solution.

Sodium atomistically according to GOST 4197−74.

Sodium arsenit-nitrite standard solution: 1.5 g of arsenious anhydride were placed in a glass with a capacity of 400−600 cm, containing 25 cmof hot 15% sodium hydroxide solution, dissolved under moderate heating, dilute with water to 120−130 cmand cooled. Then the solution was poured sulfuric acid of 1:4 to a pH of 7 on the universal indicator and another 2−3 cm. Add sodium bicarbonate to pH 7 on the universal indicator. In the resulting solution dissolve 0.85 g of sodium attestatio, transfer the solution into a measuring flask with a capacity of 1 DM, add water to the mark and mix.

Allowed the preparation of a standard solution of sodium michalowskiego ortho or 2.91 g michalowskiego sodium ortho is placed in a beaker with a capacity of 400−600 cm, 120−150 cm pouredwater and stirred until complete dissolution of the salt.

Further preparation of the solution is carried out as michalowskiego anhydride. When the content of salts water of crystallization considered in the calculation of sample needed to prepare a standard solution.

The mass concentration of the solution arsenit-sodium nitrite set at a standard piece of steel, similar in composition and the content of manganese to the test sample, carried out through all stages of analysis, as specified in clause 3.1.3.

The mass concentration of the solution arsenit-sodium nitrite (), expressed in grams of manganese, calculated by the formula

,

where  — weight of standard sample, g;

 — mass fraction of manganese in the standard sample, %;

the volume of the solution arsenit-sodium nitrite, spent on titration, sm.

(Changed edition, Rev. N 1, 2).

3.1.3. Analysis

The weight of steel depending on the mass fraction of manganese (table.3) is placed in a conical flask with a capacity of 250 cm, 40 cm, pour themixture of acids and dissolved by heating. The solution was boiled to remove oxides of nitrogen, diluted with water to about 150 cm, add 10 cmof silver nitrate, 10 cmnaternicola solution of ammonia, heated to boiling and allowed to stand in a warm place plate 1 min. the solution was Then cooled to room temperature, poured 10 cmof sodium chloride solution and titrated immediately with a solution of arsenit-sodium nitrite to the disappearance of crimson colour.

Table 3

(Changed edition, Rev. N 1).

3.1.4. Processing of the results

3.1.4.1. Mass fraction of manganese () in percent is calculated by the formula

,

where is the number of solution of arsenit-sodium nitrite consumed for titration, ml;

 — mass concentration of a solution of arsenit-sodium nitrite, expressed in grams of manganese;

the weight of steel, suitable aliquote parts of a solution taken for titration,

3.1.4.2. Permissible absolute discrepancy between the outermost of the three parallel results at a confidence level of 0.95, should not exceed the values given in table.2.

3.2. Determination of manganese in steels containing more than 1% chromium

3.2.1. The essence of the method

Deformity of manganese elements is precipitated by zinc oxide, and then in the filtrate after addition of acid the manganese (II) neccersarily oxidize ammonium in the presence of silver nitrate to manganese (VII) and the last octarepeat solution arsenit-sodium nitrite.

3.2.2. Reagents and solutions

Hydrochloric acid by the GOST 3118−77.

Ammonia water according to GOST 3760−79.

Zinc oxide according to GOST 10262−73, suspension in water: 50 g of zinc oxide, containing manganese, carbonates and reducing agents, placed in a porcelain mortar, poured hot water and triturated with a pestle, then add 250−300 cmof hot water and stirred.

Zinc oxide containing carbonates and reducing agents, pre-calcined at 800 °C.

The other reagents and solutions — p.3.1.2.

(Changed edition, Rev. N 2).

3.2.3. Analysis

The weight of steel depending on the mass fraction of manganese (table.4) is placed in a conical flask with a capacity of 250 cm, 40−50 cm, pour thesulfuric acid 1:4 and heated to dissolution. Added dropwise nitric acid until the termination of foaming solution and an excess of 2−3 cm. The solution was evaporated until the appearance of sulphuric acid fumes. If the carbides are not decomposed, then add cautiously a few drops of nitric acid and again evaporate the solution to fumes of sulfuric acid. The solution was cooled, the walls of the flask is washed with water and dissolved salts when heated.

Table 4

If the steel is difficult soluble in sulfuric and nitric acids, a portion of it is placed in a beaker with a capacity of 300−400 cm, 30 cm, pour themixture of hydrochloric and nitric acids 3:1 and heated to dissolve sample. Pour 10 cmof sulphuric acid, evaporated the solution until the appearance of sulphuric acid fumes and cooled. The side of the Cup washed with water, the solution was evaporated until the appearance of sulphuric acid fumes, cool, add about 50 cmof water and dissolved salts when heated.

The solution obtained by any of these methods, transferred to a volumetric flask with a capacity of 250 cm, add ammonia solution until you see a red-brown color. In the case of the appearance of the precipitate of hydroxide is added dropwise sulfuric acid 1:4 to dissolve the residue.

To the solution was added in small portions to the suspension of zinc oxide before the bottom of the flask a small white precipitate. The contents of the flask are cooled, made up to the mark with water, stirred and allowed sediment to settle.

The solution is filtered through dry filter «white ribbon» in a volumetric flask with a capacity of 100 cmby rinsing it the first portions of the filtrate. Fill the flask to the mark, the solution is transferred to a conical flask with a capacity of 250−300 cm, add 40 cmof the mixture of acids and end the definition, as stated in claim 3.1.3, beginning with the words: «…add 10 cmof a solution of silver nitrate…».

(Changed edition, Rev. N 1).

3.2.4. Processing of the results

3.2.4.1. Mass fraction of manganese in percent is calculated by the formula

,

where is the number of solution of arsenit-sodium nitrite consumed for titration, ml;

- mass concentration of a solution of arsenit-sodium nitrite, expressed in grams of manganese;

- the weight of steel, suitable aliquote parts of a solution taken for titration,

3.2.4.2. Permissible absolute discrepancy between the outermost of the three parallel results at a confidence level of 0.95, should not exceed the values given in table.4A.

Table 4A

(Changed edition, Rev. N 1).

4. DETERMINATION OF MANGANESE (5,00−40,0%) BY THE METHOD OF POTENTIOMETRIC TITRATION IN STEELS CONTAINING LESS THAN 0.1% OF VANADIUM AND LESS THAN 0.5% OF COBALT

4. DETERMINATION OF MANGANESE (4,0−40,0%) BY THE METHOD OF POTENTIOMETRIC TITRATION IN STEELS CONTAINING LESS THAN 0.1% OF VANADIUM AND LESS THAN 0.5% OF COBALT

4.1. The essence of the method

The method is based on the oxidation of manganese (II) to manganese (III) potassium permanganate in a neutral medium (at a pH of about 7). Iron, chromium and other elements that hinder the determination of manganese, bind in the pyrophosphate complexes.

4.2. Apparatus, reagents and solutions

The setup for potentiometric titration:

a pair of electrodes: a platinum indicator electrode and a reference electrode — a calomel, silver chloride or tungsten;

magnetic stirrer;

the DC millivoltmeter or pH meter to clearly detect the change of potential at the equivalence point during the titration with the selected pair of electrodes. If necessary, the instrument sequentially connecting a variable resistance that allows you to make measurements in the range of the instrument scale.

Hydrochloric acid by the GOST 3118−77 and diluted 1:1.

Nitric acid GOST 4461−77.

Sulfuric acid GOST 4204−77 and diluted 1:10, 1:19.

Orthophosphoric acid according to GOST 6552−80.

Ammonia water according to GOST 3760−79 and diluted 1:1.

Urea according to GOST 6691−77, 5% solution.

Sodium pyro phosphate according to GOST 342−77, saturated at room temperature the solution or potassium pyrophosphate 10% solution.

Universal indicator paper.

Sodium oxalate according to GOST 5839−77, recrystallized and dried at 105−110 °C to constant weight.

Potassium permanganate according to GOST 20490−75, a standard solution with molar concentration 0,01 mol/DM. To 15.8 g of recrystallized and dried at 120 °C of potassium permanganate are dissolved in 1 DMof water. The solution was poured 25 cmof phosphoric acid and dilute with water to 10 DM. The solution is allowed to stand for 6 days in a closed bottle, then decanted or filtered through an asbestos filter in a bottle of dark glass.

The mass concentration of the standard potassium permanganate solution set oxalate sodium and is expressed in grams of manganese by appropriate conversion. To do this in a conical flask with a capacity of 500 cmis placed 200 cmsulphuric acid 1:19, heated to 70−75 °C and added dropwise a solution of potassium permanganate until a stable pink color.

The contents of the flask add 0,1340 g of sodium oxalate and after dissolution of the sample titrated with stirring with a solution of potassium permanganate until stable for 1 min pink color. By the end of the titration, the solution temperature should not be below 60 °C.

0,1340 g of sodium oxalate corresponds to 40 ml of 0.01 M solution of potassium permanganate. Factor (f) recalculation of a standard solution of potassium permanganate 0.04 M solution is calculated by the formula

,

where  — the amount of potassium permanganate solution consumed for titration, sm.

In potentiometric titration of manganese in the presence of pyrophosphate ions 1 ml of 0.01 M potassium permanganate solution corresponds to 0,002197 g of manganese.

The mass concentration of a solution of potassium permanganate (T) expressed in grams of manganese, calculated by the formula

,

(Changed edition, Rev. N 2).

4.3. Analysis

A sample of steel weighing 0.25 g were placed in a glass with a capacity of 400 cm, 30 cm, pouredhydrochloric acid 1:1, 5 cmof nitric acid and heated to dissolve sample. The solution was evaporated to a volume of approximately 3−5 cm, add 50 cmof water, dissolve salt, add 5 cmof the urea solution and cooled.

To the solution add ammonia solution dropwise until the appearance of reddish-brown color. If will precipitate hydroxides of metals, it is dissolved by adding dropwise sulfuric acid 1:10. Then the solution was poured 150 cmof a saturated solution of sodium pyrophosphate or potassium pyrophosphate solution and set the pH near 7 on the universal indicator paper by adding, if necessary, drop by drop sulfuric acid of 1:10 or a solution of ammonia 1:1.

Into the beaker with the test solution is placed the electrodes include a magnetic stirrer, stirred solution of 0.5−1 min and without turning off the stirrer, the manganese titrated solution of potassium permanganate. First, a solution of potassium permanganate, poured quickly, and near the equivalence point — drop by drop, recording the volume of solution in the burette and the readings after adding each drop. The volume of solution of potassium permanganate spent for titration to the maximum change of the readings taken for the volume used for titration.

After each titration the electrode is washed with sulphuric acid 1:10 and water. Upon completion of the work leave the electrodes immersed in the glass of water.

4.4. Processing of the results

4.4.1. Mass fraction of manganese () in percent is calculated by the formula

,

where is the volume of potassium permanganate solution consumed for titration, ml;

 — mass concentration of a solution of potassium permanganate, expressed in grams of manganese;

the weight of steel,

4.4.2. Permissible absolute discrepancy between the outermost of the three parallel results at confidence probability P = 0.95 does not exceed the values given in table 5.

Table 5

(Changed edition, Rev. N 3).

5. ATOMIC ABSORPTION METHOD FOR THE DETERMINATION OF MANGANESE (0,10−5,00%)

5. ATOMIC ABSORPTION METHOD FOR THE DETERMINATION OF MANGANESE (0,01−5,0%)

5.1 the essence of the method

The method is based on measuring the degree of absorption of resonance radiation by free atoms of manganese, formed as a result of spraying the test solution into the flame of the air-Atitlan or acetylene-nitrous oxide.

Weighed sample was dissolved in a mixture of hydrochloric and nitric acids, evaporate the solution to dryness and dry the residue is dissolved in hydrochloric acid. After appropriate dilution of the solution used for the determination of manganese by atomic absorption method.

(Changed edition, Rev. N 3).

5.2. Apparatus, reagents and solutions

Atomic absorption spectrophotometer fiery.

Lamp with hollow cathode for the determination of manganese.

Acetylene according to GOST 5457−75.

A tank of nitrous oxide.

The compressor supplying compressed air, or compressed air.

Hydrochloric acid by the GOST 3118−77.

Nitric acid GOST 4461−77.

Carbonyl iron of special purity.

Manganese metal brands Mr 00 GOST 6008−82.
________________
* On the territory of the Russian Federation the document is not valid. Valid GOST 6008−90. — Note the manufacturer’s database.

Manganese hydrochloric acid, standard solutions of A and B.

Solution A. 1 g of metallic manganese is dissolved by heating in 20 cmof hydrochloric acid carefully drop by drop, add 1−2 cmof nitric acid and boil to remove oxides of nitrogen. The solution was transferred to a volumetric flask with a capacity of 1 DM, cooled, made up to the mark with water and mix.

1 ml of a standard solution And contains 1 mg of manganese.

Solution B. 10 cmof the solution And placed in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

1 cmstandard solution B contains 0.1 mg of manganese.

Solution: the 20 cmstandard solution B is placed in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

1 cmstandard solution contains 0.02 mg of manganese

(Changed edition, Rev. N 2, 3).

5.3. Preparation of the device

Training device produced in accordance with the attached instructions. Set the spectrophotometer at a resonance line of 279.5 nm or 403,0 nm depending on the manganese content in the sample (table.6). After switching on the gas flow and ignition of the burner spray water and set the zero of the instrument.

Table 6

5.4. Analysis

The weight of steel depending on the mass fraction of manganese (table.6) is placed in a beaker with a capacity of 100 cmand dissolved in a mixture of 10 cmof hydrochloric and 3−5 cmof nitric acid. The solution was evaporated to dryness. The dry residue is dissolved in 4 cmof hydrochloric acid, the solution transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix. Part of the solution filtered through a dry filter «white ribbon» in the conical flask by rinsing it the first portions of the filtrate.

Through the analysis of spend control experience.

Spray the solution in the reference experiment and the sample solution to obtain stable results, for each solution.

Before spraying each solution is sprayed water to obtain the zero readings.

(Changed edition, Rev. N 2).

5.5. Construction of calibration graphs

5.5.1. Construction of calibration curve for the mass fraction of manganese from 0.1 to 0.5%

In a volumetric flask with a capacity of 100 cmplaced 2, 4, 6, 8 and 10 cmstandard solution B hydrochloric acid manganese, which corresponds to 0,2; 0,4; 0,6; 0,8 and 1 mg manganese. Add 4 cmof hydrochloric acid, made up to the mark with water and mix.

For preparation of the null solution in a volumetric flask with a capacity of 100 cmis placed 4 cmof hydrochloric acid, made up to the mark with water and mix.

Set up the device on resonance line of 279.5 nm.

The solutions were sprayed in order of increasing absorption, starting from the zero solution. Before spraying each solution is sprayed water.

From the average value of the optical density of each solution is subtracted the average value of the optical density of the zero solution.

On the found values of optical density and corresponding masses of manganese build the calibration graph.

5.5.2. Construction of calibration curve for the mass fraction of manganese from 0.5 to 5.00%.

In a volumetric flask with a capacity of 100 cmplaced 1, 2, 3, 4 and 5 cmstandard solution A, which corresponds to 1, 2, 3, 4 and 5 mg of manganese, add 4 cmof hydrochloric acid, dilute to the mark with water and mix. For preparation of the null solution in a volumetric flask with a capacity of 100 cmis placed 4 cmof hydrochloric acid, made up to the mark with water and mix.

Set up the device on resonance line 403,0 nm.

Then do as specified in clause 5.5.1.

5.5.3. Construction of calibration curve for the mass fraction of manganese from 0.01 to 0.1%.

Six glasses with a capacity of 250−300 cmis placed 0.2 g of iron was dissolved in 10 cmof hydrochloric and 3−5 cmof nitric acid. The solutions were evaporated to dryness. The dry residue is dissolved in 4 cmof hydrochloric acid and the solutions were transferred to volumetric flasks with a capacity of 100 cm. Five volumetric flasks add 1,0; 2,0; 4,0; 6,0 and 10,0 cmstandard solution, which corresponds to 0,02; 0,04; 0.08; 0.12 and 0.20 mg of manganese, made up to the mark with water and mix. Then do as specified in clause 5.5.1.

As the zero solution solution is used in the sixth flask, not containing manganese.

(Added, Rev. N 3).

5.6. Processing of the results

Calculate the average value of optical density of control solution and subtract this value from the average value of the optical density of the tested solutions.

According to the calibration schedule find a lot of manganese in milligrams of the test solution.

5.6.1. Mass fraction of manganese () in percent is calculated by the formula

,

where is the weight of steel, suitable fotometricheskoe aliquote part of the analyzed solution, mg;

 — weight of manganese, was found in the calibration schedule, mg.

5.6.2. Permissible absolute discrepancy between the outermost of the three parallel results at a confidence level should not exceed the values given in table.2.

(Changed edition, Rev. N 1).