GOST 22536.5-87

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  ГОСТ 22536.5-87

GOST 22536.5−87 (ST SEV 486−88, ISO 629−82) carbon Steel and unalloyed cast iron. Methods for determination of manganese (with Amendments No. 1, 2)

GOST 22536.5−87
(ST CMEA 486−88,
ISO 629−82)*
_______________
* Changed the wording, Rev. N 1.

Group B09

STATE STANDARD СОЮ3А SSR

CARBON STEEL AND UNALLOYED CAST IRON

Methods for determination of manganese

Carbon steel and unalloyed cast iron.
Methods for determination of manganese

AXTU 0809

Valid from 01.01.88
to 01.01.98*
______________________________
* Expiration removed
Protocol N 7−95 Interstate Council
for standardization, Metrology and certification.
(IUS N 11 1995). — Note the CODE.

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of ferrous metallurgy of the USSR

PERFORMERS

D. K. Nesterov, PhD. tech. Sciences; S. I. Rudyuk, PhD. tech. science; N.N. Gritsenko, PhD. chem. Sciences (head of subject); V. F. Kovalenko, PhD. tech. Sciences; S. V. Spirina, PhD. chem. Sciences (head of subject); O. M. Kirzhner

2. APPROVED AND put INTO EFFECT by decision of the USSR State Committee for standards from 20.02.87 N 301

3. REPLACE GOST 22536.5−77

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

5. Reprinting. December, 1987

The Change No. 1 approved by resolution of Gosstandart of the USSR from 09.10.89 N 3041, introduced with effect from 01.01.90 and published in IMS No. 1, 1990

Change No. 1 entered the law office of «Code» in the text IUS N 1, 1990

AMENDED No. 2, approved by resolution of Gosstandart of the USSR from 28.03.90 No. 659, introduced with effect from 01.10.90 and published in IMS No. 6, 1990

Change 2 N entered the law office of «Code» in the text IUS N 6, 1990


This standard establishes titrimetric (mass fraction in manganese 0,3−3,0%), potentiometric (when the mass fraction of manganese, 0.5 to 3.0%), photometric (at a mass fraction of manganese of 0.005 to 3.0%), atomic absorption (at a mass fraction of manganese 0,1−3,0%) methods for determination of manganese in carbon steel and unalloyed cast iron.

The standard complies ST SEV 486−88 in part by the photometric method, ISO 629−82.

(Changed edition, Rev. N 1).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 22536.0−87.

2. TITRIMETRIC METHOD

2.1. The essence of the method

The method is based on the oxidation of divalent manganese in sulfuric acid solution to pneumococcal neccersarily ammonium in the presence of silver nitrate. The obtained manganese acid octarepeat solution arsenit sodium nitrite or with a solution servational sodium (sodium thiosulfate).

2.2. 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.

Ammonium neccersarily according to GOST 20478−75, a freshly prepared solution with a mass concentration of 200 g/DM.

Silver nitrate according to GOST 1277−75, a solution with a mass concentration of 2.0 g/DM.

Universal indicator paper.

Sodium chloride according to GOST 4233−77, a solution with a mass concentration of 5 g/DM.

Arsenious anhydride according to GOST 1973−77.

Sodium bicarbonate according to GOST 4201−79.

Sodium carbonate according to GOST 83−79.

Sodium hydroxide according to GOST 4328−77, a solution with a mass concentration of 150 g/DM.

Sodium nitrate according to GOST 4197−74.

Sodium mistakemistake ortho (NaAsO) according to normative-technical documentation.

Chernovetskiy sodium (thiosulfate) according to normative-technical documentation, standard solution; 0.65 g of sodium thiosulfate dissolved in 1 DMsvejeprokipachenna and cooled water, add 0.1 g of sodium carbonate and stirred. The solution is kept for 2−3 days.

Sodium arsenit-nitrite standard solution: 1.5 g of arsenious anhydride is dissolved in a beaker with a capacity of 400−600 cm25 cmhot sodium hydroxide solution (150 g/DM), diluted to 120 cmof water, cooled, neutralized with sulfuric acid, diluted 1:4, to a pH of 7 on the universal indicator and add 2−3 cmto the excess. Excess sulfuric acid is neutralized with sodium bicarbonate to pH 7 on the universal indicator. To the obtained solution are added 0.85 g of sodium nitrate and stirred to dissolve the soda. The contents of the beaker poured into a volumetric flask with a capacity of 1 DM, made up to the mark with water, mix thoroughly and set, the mass concentration of a standard solution.

A solution of arsenit-nitrite can also be prepared from mistakemistake sodium ortho; 1.0 g michalowskiego sodium ortho is placed in a beaker with a capacity of 400−600 cm, 120−150 cm pourwarm water, add 0.5 g of sodium carbonate, 0.75 g of sodium attestatio, mix and dilute with water to 1 DM.

When the content of salts water of crystallization considered in the calculation of sample needed to prepare a standard solution. The mass concentration of arsenit-sodium nitrite and sodium thiosulfate set according to the standard model, similar in chemical composition and the content of manganese to the sample and carried through all stages of analysis, as mentioned in paragraph 2.3. The mass concentration of the solution arsenit-sodium nitrite or sodium thiosulfate , expressed in grams of manganese per 1 cmof a solution, calculated by the formula

,

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

 — weight of standard sample, g;

the volume of the solution arsenit-sodium nitrite or sodium thiosulfate consumed in the titration, sm.

2.3. Analysis

The weight of steel or cast iron depending on the mass fraction of manganese (see table. 1) is placed in a conical flask with a capacity of 250 cm, 30 cm, pour themixture of acids and dissolved by heating. The solution was boiled to remove oxides of nitrogen. In the analysis of cast iron a precipitate of graphite and silicic acid is filtered off and washed six or seven times with hot distilled water. Filter the precipitate discarded.

Table 1

The solution is diluted with water to 130−150 cm, add 10 cmof a solution of silver nitrate, 15 cmnaternicola a freshly prepared solution of ammonia, heated to boiling and allowed to stand in a warm place until the termination of allocation of bubbles of oxygen. The solution was then cooled in running water to room temperature (20−22 °C), poured 10 cmof sodium chloride solution and titrated immediately with a solution of arsenit-sodium nitrite to a slightly pink color, and then add it drop by drop until complete disappearance of the pink color.

Instead of arsenit-sodium nitrite titration, you can apply a solution of sodium thiosulfate.

2.4. Processing of the results

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

,

where is the mass concentration of the solution arsenit-sodium nitrite or sodium thiosulfate, expressed in g/cmof manganese;

the volume of the solution arsenit-sodium nitrite or sodium thiosulfate consumed in the titration, cm;

 — the weight of the portion,

2.4.2. Norms of accuracy and norms control the accuracy of determining the mass fraction of manganese are given in table. 2.

Table 2

(Changed edition, Rev. N 2).

3. POTENTIOMETRIC METHOD

3.1. The essence of the method

The method is based on the oxidation of divalent manganese to permanganate with potassium trivalent, neutral (pH 7) or slightly alkaline solution in the presence of sodium pyrophosphate and potentiometric determination of the titration end.

3.2. Equipment and reagents

The setup for potentiometric titration:

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

magnetic or mechanical 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 or GOST 14261−77 and diluted 1:1.

Sulfuric acid GOST 4204−77 or GOST 14262−78 and diluted 1:4, 1:10.

Nitric acid GOST 4461−77 or GOST 11125−84.

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

Sodium pyrophosphate according to GOST 342−77, a solution with a mass concentration of 100 g/DM.

Universal indicator paper.

Urea according to GOST 6691−77.

Potassium permanganate according to GOST 20490−75, a standard solution with molar concentration of the equivalent 0,02 mol/DM: 0.64 g of potassium permanganate dissolved in 1 DMof water. The solution is poured into a bottle made of dark glass and leave it for 8−10 days, then decanted or filtered through an asbestos filter in a bottle of dark glass.

The mass concentration of potassium permanganate solution set not earlier than the day following its filtration according to the standard solution of manganese or standard sample, similar in composition and content of manganese to the sample.

A portion of potassium permanganate (recrystallized) weighing 0.15 g is dissolved in 30 cmof water, add 10 cmof hydrochloric acid and evaporated to dryness. The last operation is repeated twice more. Salt is dissolved in 10 cmof hydrochloric acid, transferred to a volumetric flask with a capacity of 250 cm, is diluted to the mark with water and mix.

Select aliquot part of the solution is 25 cmin a glass with a capacity of 400 cm, with 100 cmof saturated solution of sodium pyrophosphate and 0.5 g of urea. The surgery is performed with continuous stirring of the solution. Then do as stated in claim 3.3.

The mass concentration of a solution of potassium permanganate , expressed in grams of manganese per 1 cmof a solution, calculated by the formula

,

where is the weight of potassium permanganate, the corresponding aliquote part of the solution, g;

 — the volume of potassium permanganate solution consumed for titration, cm;

0,3476 — the ratio of potassium permanganate to manganese.

3.3. Analysis

The weight of steel or cast iron weighing 0.2 g was placed in a beaker with a capacity of 250−300 cmand dissolved under moderate heating in 20−30 cmof hydrochloric acid diluted 1:1, or sulfuric acid, diluted 1:4, oxidized by adding dropwise nitric acid until the termination of foaming. The solution was evaporated to 3−5 cm, add 50−100 cmof water and neutralized with ammonia solution diluted 1:1 before precipitation of hydroxides of iron. If will precipitate hydroxides of metals, it is dissolved by adding dropwise hydrochloric acid, diluted 1:1. Then pour 100 cmof a solution of pyrophosphate of sodium and checked by universal indicator medium solution. If the environment is acidic solution, pour the solution of sodium pyrophosphate to a pH of 7, alkaline if — dropwise hydrochloric acid diluted 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, or titrating to a sharp deflection of the instrument pointer. The volume of potassium permanganate solution, the maximum change in the readings, accept for the volume used for titration.

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

3.4. Processing of the results

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

,

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

 — mass concentration of a solution of potassium permanganate, expressed in grams of manganese per 1 cmof solution;

 — the weight of the portion,

3.4.2. Norms of accuracy and norms control the accuracy of determining the mass fraction of manganese are given in table. 2.

(Changed edition, Rev. N 2).

4. PHOTOMETRIC METHOD

4.1. The essence of the method

The method is based on oxidation of manganese (II) to manganese (VII) ignobilis potassium or sodium, and measuring the optical density of the colored solution at a wavelength of 530−545 mm.

(Changed the wording. Izm. N 1).

4.2. Equipment and reagents

Spectrophotometer or photoelectrocolorimeter.

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

Orthophosphoric acid according to GOST 6552−80.

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

Potassium permanganate according to GOST 20490−75.

Hydrogen peroxide according to GOST 10929−76.

Potassium cognately according to normative-technical documentation.

Sodium atomistically according to GOST 4197−74, a solution with a mass concentration of 50 g/DM.

The mixture of acids to dissolve: to 550 cmwater 90 cm pouredsulfuric acid under stirring, cooled and poured 260 cmof nitric acid.

Acid chloride with a density of 1.54 g/cmor 1.67 g/cmand a solution (1:500).

Sodium cognately according to normative-technical documentation, solution: 50 g jednolitego potassium or sodium dissolved in 200 cmof nitric acid and 500 cmof water, dilute with water to volume of 100 cmand mixed.

Standard solutions of manganese

Solution a: 0,5754 g of potassium permanganate (recrystallized) were placed in a glass with a capacity of 600 cmand dissolved in 300 cmof water. To the solution was added 20 cmof sulphuric acid, diluted 1:4, and carefully, drop by drop, while stirring, add the hydrogen peroxide to the bleaching solution. The solution was evaporated until the formation of salts. The salt was dissolved in 20−30 cmof water, the solution was cooled, transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix. 1 cmof the solution contains 0.0002 g of manganese.

Solution B: 50 cmstandard solution And placed in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix. 1 cmof a solution contains 0.0001 g of manganese.

Solution In 25 cmof a solution transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix. The solution is prepared before use.

1 cmof the solution contains 0,000025 g of manganese.

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 a pH of 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.

(Changed red

action, Rev. N 1).

4.3. Analysis

4.3.1. Determination of manganese at a mass fraction of 0.05−2.0%, from hodnoceni potassium.

The weight of steel or cast iron depending on the mass fraction of manganese (table. 3) is placed in a beaker with a capacity of 250−300 cmand dissolved under moderate heating in 30−50 cmof the mixture of acids.

Table 3

The solution was boiled to remove oxides of nitrogen and cooled. If there is a precipitate (graphite, silicic acid), it is filtered off and washed six or seven times with hot water. The filter with the sediment is discarded and the filtrate evaporated to a volume of less than 100 cm. When the mass fraction of manganese from 0.05 to 0.25% solution transferred to a conical flask with a capacity of 100 cmand continue with the analysis of solution sample the full sample. If the sample contains more than 0.25% manganese, the solution was transferred to volumetric flask with a capacity of 100 cm, made up to the mark with water, mix and take aliquot part in accordance with the table. 3 in a conical flask with a capacity of 100 cmand adding 6 cmof sulphuric acid diluted 1:1.

The resulting solution was added 2−2,5 cmof phosphoric acid and 0.3 g of potassium periodate. The solution is diluted with water to 80 cm, heated to boiling, boiled for 1 min and left in a water bath at a temperature of about 90 °C for 40−50 min. the Solution was cooled, transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water containing no reducing agents, and mixed.

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 530−545 nm.

Solution comparison is the remaining part of the colored solution of each sample of the sample, which regenerate manganous acid by adding a few drops of solution of sodium attestatio.

The analysis results calculated by a calibration chart or by comparison with a standard sample similar in composition to the sample and carried through all stages of the analysis.

(Changed edition, Rev. N 1, 2

).

4.3.2. Construction of calibration curve

2.5 g of iron carbonyl was placed in a beaker with a capacity of 250−300 cm, flow 50 cmof the mixture of acids. The solution was boiled to remove oxides of nitrogen, cooled, transferred to a volumetric flask with a capacity of 250 cm, made up to the mark with water and mix. Eight conical flasks with a capacity of 100 cmplaced at 10 cmof the resulting solution, seven of them successively added 1; 2; 3; 4; 5; 6; 7 cmstandard solution of potassium permanganate, which corresponds to 1·10; 2·10; 3·10; 4·10; 5·10; 6·10; 7·10g manganese. In the eighth flask conduct control experience on the content of manganese in the reagents.

The solutions in the flasks was added 6 cmof sulphuric acid diluted 1:1, 2 cmof phosphoric acid and 0.3 g of potassium periodate. The solutions were diluted with water to 80 cm, heated to boiling, boiled for 1 min and left in a water bath at a temperature of about 90 °C for 40−50 min. the Solutions were cooled, transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water containing no reducing agents, and mixed.

Absorbance measured on the spectrophotometer at a wavelength of 545 nm or photoelectrocolorimeter with a filter having a region of transmittance in the wavelength range of 530−545 nm. As a solution comparison solution is used in the reference experiment.

The found values of optical density and corresponding masses of manganese build the calibration graph. Allowed construction of calibration curve in the coordinates: the optical density of mass $

I of manganese.

4.3.3. Determination of the mass fraction of manganese of 0.005−3.0% in the presence of perchloric acid.

Weighed samples of ground mounted depending on the manganese content, according to table. 3A is placed in a beaker with a capacity of 250 cm.

Table 3A

The sample is dissolved in 50 cmof the mixture of acids under moderate heat and once dissolved, add dropwise 2 cmof nitric acid and evaporated to a small volume, avoiding the allocation of sulfate salts. Then add 20 cmof perchloric acid and gently evaporated until the appearance of fumes of perchloric acid and then maintained in this state for 10 minutes.

The contents of the beaker cooled, diluted with water to a volume of 50−60 cmand boil. If necessary, the solution was filtered, and the filter and the precipitate washed with hot solution of perchloric acid (1:500) and discarded. The solution or filtrate is cooled, transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix (stock solution).

Depending on the mass fraction of manganese into the conical flask with a capacity of 250 cmtaken aliquot part of the basic solution and add a mixture of acids and water in the amount indicated in the table. 3b.

Table 3b

The contents of the flask boiled, is poured 10 cmof the solution jednolitego potassium or sodium and continue to boil the solution for 2 min, after which the solution is kept for 10 minutes at a temperature of 90 °C. the Solution was cooled to room temperature, transferred to a volumetric flask with a capacity of 100 cm, previously washed with water containing no reducing agents, add this to the mark with water and mix.

Measure the optical density of the solution on the spectrophotometer at a wavelength of 535−545 nm. Solution comparison is water. The solution in the flask decolorized by adding a few drops of a solution of sodium attestatio, next, rinse the cuvette with this solution, determine the optical density in the same cell. The value of the optical density of decolorized solution is subtracted from the values of optical density of the sample solution.

Simultaneously with the sample analysis spend control experience. The value of optical density in the reference experiment is subtracted from the optical density of the sample solution.

The mass of manganese determined by the calibration schedule.

4.3.4. To construct the calibration curve for the mass concentration of manganese from 0.005 to 0.05% in seven glasses with a capacity of 250 cmis placed on a 2.00 g iron, is added to 50 cmof a mixture of acid and gently heated to dissolve the iron. Then the slurry is oxidized by adding dropwise 2 cmof nitric acid, is added to 20 cmof perchloric acid, the solution evaporated until the appearance of fumes of perchloric acid and then maintained in this state for 10 minutes.

Then the slurry is cooled, diluted with water to a volume of 50−60 cmand boil.

If necessary, the solutions were filtered, the filter residue washed with hot solution of perchloric acid (1:500). The solution or the filtrate is cooled, transferred to volumetric flasks with a capacity of 100 cm, made up to the mark with water and mix.

Seven of cups with a capacity of 250 cmis placed 40 cmof the resulting solution of iron, selected from seven volumetric flasks, and add 0; 1,0; 2,0; 5,0; 10,0; 15,0 20.0 cmstandard solution, which corresponds to: 0; 0,025; 0,050; 0,125; 0,250; 0,375 and 0,500 mg of manganese, solutions diluted with water to 60 cm, then add 5 cmof the mixture of acids, solutions boil add up to 10 cmjednolitego solution of potassium or sodium, and boiled for 2 min. the Solutions were allowed to stand at 90 °C for 10 min, then cooled to room temperature, transferred to volumetric flasks with a capacity of 100 cm, previously washed with water containing no reducing agents, add this to the mark with water and mix.

Measure the optical density of colored solutions on the spectrophotometer at a wavelength of 535−545 nm.

Solution comparison is the solution not containing a standard solution of manganese. According to the obtained values of optical density of solutions and the corresponding content of manganese build the calibration

schedule.

4.3.5. To construct the calibration curve for the mass concentration of manganese in excess of 0.05% in a glass with a capacity of 250 cmis placed 1.00 g of iron and then do as in the preparation of iron solution according to claim 4.3.4.

Then in six sample beakers with a capacity of 250 cmtaken at 10 cmof a solution of iron and measure: 0; 2,0; 5,0; 10,0; 15,0 20.0 cmstandard solution B, which corresponds to 0,0; 0,2; 0,5; 1,0; 1,5 and 2.0 mg of manganese, solutions diluted with water to a volume of 35 cmand add 20 cmof a mixture of acids. The solutions were boiled, added to 10 cmjednolitego solution of potassium or sodium, and then do as specified in clause 4.3.4

.

4.3.3-.4.3.5. (Introduced in addition. Izm. N 1).

4.4. Processing of the results

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

,

where is the mass of manganese was found in the calibration schedule g;

 — the weight of the portion of the sample corresponding to aliquote part of the solution,

4.4.2. Norms of accuracy and norms control the accuracy of determining the mass fraction of manganese are given in table. 2.

(Changed edition, Rev. N 2).

5. ATOMIC ABSORPTION METHOD

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 in a flame air-acetylene.

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.

5.2. Equipment and reagents

Atomic absorption spectrophotometer fiery.

Lamp with hollow cathode for the determination of manganese.

Acetylene according to GOST 5457−75.

The compressor supplying compressed air, or compressed air.

Hydrochloric acid by the GOST 3118−77 or GOST 14261−77.

Nitric acid GOST 4461−77 or GOST 11125−84.

Manganese metal brands Mr 00 GOST 6008−82.

Standard solutions of hydrochloric acid manganese

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 cmstandard solution contains 0.001 g of manganese.

Solution B: 10 cmsolution 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 0.0001 g of manganese

.

5.3. Preparation for assay

The device is prepared in accordance with the enclosed instructions. Set the spectrophotometer at a resonance line of 279.5 nm with a mass fraction of manganese is less than 0.5% or 403,0 nm when the mass fraction of manganese of more than 0.5%. After switching on the gas flow and ignition of the burner spray water and set the zero readings.

5.4. Analysis

5.4.1. The weight of steel or cast iron depending on the mass fraction of manganese (table. 4) 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» into the conical flask, it was washed first portions of the filtrate.

To prepare a test 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.

Spray the control and test solutions in order of increasing absorption to obtain stable readings for each solution. Before the suction of the measuring solution is sprayed water to wash the system and check the zero point.

Table 4

5.4.2. Construction of calibration graphs

5.4.2.1. 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 1; 2; 3; 4; 5 and 6 cmstandard solution B hydrochloric acid manganese, which corresponds to 1·10; 2·10; 3·10; 4·10; 5·10and 6·10g manganese. Add 4 cmof hydrochloric acid, made up to the mark with water and mix.

To prepare a test 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 control 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 optical density of control solution. On the found values of optical density and corresponding masses of manganese build calibration gr

Afik.

5.4.2.2. Construction of calibration curve for the mass fraction of manganese from 0.5 to 3.0%.

In a volumetric flask with a capacity of 100 cmis placed 1,0; 1,5; 2,0; 2,5; 3,0 and 3,5 cmstandard solution A, which corresponds to 1·10; 1,5·10; 2·10; 2,5·10; 3·10; 3,5·10g of manganese, add 4 cmof hydrochloric acid, dilute to the mark with water and mix. To prepare a test 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 5.4

.2.1.

5.5. Processing of the results

5.5.1. 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 test solution, in grams.

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

,

where is the mass of manganese was found in the calibration schedule g;

the weight of steel,

5.5.3. Norms of accuracy and norms control the accuracy of determining the mass fraction of manganese are given in table. 2.

(Changed edition, Rev. N 2).