GOST 851.6-93

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  ГОСТ 851.6-93

GOST 851.6−93 Magnesium primary. Methods for determination of manganese

GOST 851.6−93

Group B59

INTERSTATE STANDARD

MAGNESIUM PRIMARY

Methods for determination of manganese

Primary magnesium.
Methods for determination of manganese

ISS 77.120.20
AXTU 1709

Date of introduction 1997−01−01

Preface

1 DEVELOPED by the Ukrainian scientific-research and design Institute of titanium

INTRODUCED by Gosstandart of Ukraine

2 ADOPTED by the Interstate Council for standardization, Metrology and certification (Protocol No. 3 dated February 17, 1993)

The adoption voted:

The name of the state	The name of the national authority for standardization
The Republic Of Armenia	Armastajad
The Republic Of Belarus	Belstandart
The Republic Of Kazakhstan	Gosstandart Of The Republic Of Kazakhstan
The Republic Of Moldova	Moldovastandart
Russian Federation	Gosstandart Of Russia
Turkmenistan	Turkmengeologiya
The Republic Of Uzbekistan	Standards
Ukraine	Gosstandart Of Ukraine

3 Decree of the Russian Federation Committee on standardization, Metrology and certification from February, 20th, 1996 N 77 interstate standard GOST 851.6−93 introduced directly as state standard of the Russian Federation from January 1, 1997

4 REPLACE GOST 851.6−87

5 REISSUE

INFORMATION DATA

REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

The designation of the reference document referenced	The number of the paragraph, subparagraph
GOST 8.315−97	2.2; 3.2; 4.2
GOST 4204−77	2.2
GOST 4461−77	2.2
GOST 5457−75	3.2; 4.2
GOST 6008−90	2.2; 3.2; 4.2
GOST 6552−80	2.2
GOST 10929−76	2.2
GOST 11125−84	3.2; 4.2
GOST 14261−77	3.2
GOST 25086−87	1.1; 1.4; 2.3.2; 2.4.3; 3.4.3; 4.3.2; 4.4.3
THAT 6−09−02−364−83	2.2
THAT 6−09−2540−87	2.2

This standard specifies the photometric (with a mass fraction of manganese from 0.001 to 0.10%) and atomic absorption (at a mass fraction of manganese from 0.0005 to 0.050%) methods for determination of manganese in primary magnesium.

If there are differences in the analysis carried out by the photometric method.

1 General requirements

1.1 General requirements for methods of analysis GOST 25086.

1.2 Mass fraction of manganese is determined from the two parallel batches.

1.3 When building a calibration curve each point build on the average result of the three definitions of optical density or atomic absorption.

1.4 Permitted discrepancies in the results of the analysis of the same samples obtained by the two methods, calculated according to GOST 25086.

1.5 When placing the results of the analysis make reference to this standard, indicate method and results of control accuracy.

2 the Photometric method for the determination of manganese

2.1. The essence of the method

The method is based on the oxidation of divalent manganese to pneumococcal with subsequent measurement of optical density of the solution.

2.2 the Instrument, reagents and solutions

The spectrophotometer or photoelectric colorimeter.

Nitric acid — according to GOST 4461, diluted 1:1.

Sulphuric acid — according to GOST 4204, diluted 1:4.

Orthophosphoric acid — according to GOST 6552, diluted 1:1.

Potassium cognately — on the other 6−09−02−364.

Hydrogen peroxide — according to GOST 10929, solution with a mass concentration of 300 g/DM.

Manganese metal brands Мп00 — according to GOST 6008.

Potassium permanganate, standard-caption — on the other 6−09−2540, solution with a molar concentration of 0.02 mol/DM.

State standard samples made in accordance with GOST 8.315.

Standard solutions of manganese:

Solution a: a solution of permanganate of potassium with molar concentration of 0.002 mol/DM, made with standard-titre.

1 cmof the solution contains 1.1 mg of manganese.

Solution B: 9.1 cmsolution And placed in a volumetric flask with a capacity of 100 cm, add 5 cmof sulfuric acid solution, and dropwise a solution of hydrogen peroxide with continuous stirring to the bleaching solution. The solution is boiled to eliminate excess hydrogen peroxide, cooled to room temperature, made up to the mark with water and mix; fit for use for 6 months.

1 cmof a solution contains 0.1 mg of manganese.

Solution: 1.0 g of manganese dissolved in 50 cmof a solution of nitric acid. After removal of oxides of nitrogen by boiling the solution was cooled to room temperature, transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

1 cmof the solution contains 1 mg of manganese.

Solution G: 10 cmsolution is placed in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix; fit for use for 6 months.

1 cmsolution G contains 0.1 mg of manganese.

Solution D: 20 cmof solution B or G is placed in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix; prepare before use.

1 cmof solution D contains 0.02 mg of manganese.

Water, not containing reducing agents: to 1000 cmof distilled water add 10 cmsulphuric acid and bring to a boil. Add 0.1 g of potassium jednolitego and Ki

Patt 10 min.

2.3 analysis

2.3.1 Sample weight of 0.5 or 1.0 g (see table 1) placed in a conical flask with a capacity of 250 cm, add 15 cmof water and small portions of 25 cmof sulfuric acid solution. After the violent reaction add 5 cmof nitric acid and boil to complete dissolution of the sample. Then add 20 cmof nitric acid, heated to boiling, the hot solution was added 2 cmof a solution of phosphoric acid, 0.5 g of potassium jednolitego and boiled for 10 min in low heat. Then turn off the hotplate and leave it solutions for 20−30 minutes while maintaining a volume of 30 cmby adding water.

The solution was cooled to room temperature, transferred to a volumetric flask with a capacity of 50 cm, made up to the mark with water, mix and measure the optical density of the solution at a wavelength of from 560 to 540 nm. Solution comparison is the solution of the reference experiment.

Table 1

Mass fraction of manganese, %	The mass of charge, g	Standard solution
From 0.001 to 0.01	1,0	D
«Of 0.005» to 0.05	1,0	B or G
«Of 0.010» to 0.10	0,5	B or G

2.3.2 Construction of calibration curve

To build a calibration curve in six of the seven conical flasks with a capacity of 250 cmis placed 0,5; 1,0; 2,0; 4,0; 5,0 cmstandard solution B, C or D (see table 1), which corresponds to 0,05; 0,10; 0,20; 0,40; 0,50 mg manganese (for standard solutions B and d) or 0,01; 0,02; 0,04; 0,08; 0,10 mg manganese (standard solution D).

A seventh solution of the flask is a solution of the reference experiment. All flasks is poured 40 cmwater and 15 cmof sulfuric acid solution, 25 cmof nitric acid, heated to boiling, add 2cmof a solution of phosphoric acid and then act as described in 2.3.1.

Solution comparison is the solution of the reference experiment.

According to the obtained values of optical density calibration curve built in accordance with GOST 25086.

2.4 Processing of results of analysis

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

, (1)

where is the mass of manganese in the sample solution found by the calibration schedule g;

 — the weight of the portion,

2.4.2 Standards of accuracy of analysis results

The values of the characteristics of error definitions: permitted discrepancies in the results of parallel measurements (the rate of convergence) and the results of the analysis of the same samples obtained in two laboratories or in the same, but in different conditions (a measure of reproducibility), and the margins of error definitions ( — accuracy rate) at a confidence level =0.95 is shown in table 2.

Table 2

Mass fraction of manganese, %	Characteristics error definitions %
From 0.001 to 0.003 incl.	0,0005	0,0008	About 0.0006
SV. 0,003 «0,010 «	0,0010	0,0015	0,0012
«0,010» 0,030 «	0,0020	0,0030	0,0020
«0,030» 0,100 «	0,0030	0,0040	0,0030

2.4.3 Control of accuracy of analysis results

Control of accuracy of analysis results is carried out according to state standard sample in accordance with GOST 25086.

It is allowed to conduct control of accuracy by the method of additives in accordance with GOST 25086.

Additives is a standard solution B, C or D.

3 Atomic absorption method for the determination of manganese at a mass fraction of from 0.0005 to 0.0025%

3.1 Method based on the measurement of atomic absorption of manganese at a wavelength of 279.5 nm in the electrothermal atomization mode.

The determination is carried out by standard addition.

3.2 Equipment, reagents and solutions

Spectrophotometer atomic absorption equipped with graphite atomizer, a source of excitation of spectral lines of manganese.

Acetylene — GOST 5457.

Nitric acid — according to GOST 11125, diluted 1:1.

Hydrochloric acid — according to GOST 14261, diluted 1:1.

Manganese metal brands Мп00 — according to GOST 6008.

State standard samples made in accordance with GOST 8.315.

Water bidistilled.

Standard solutions of manganese:

Solution a: 0,100 g of manganese dissolved in 20 cmof a solution of nitric acid under heating. After the termination of allocation of oxides of nitrogen the solution was cooled to room temperature, transferred to a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix; fit for use for 6 months.

1 cmof solution A contains 0.1 mg of manganese.

Solution B: 5 cmsolution And placed in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix; prepare before use.

1 cmof solution B contains 5 µg of manganese.

3.3 analysis

3.3.1 Sample the sample weight of 0.5 g was placed in six beakers with a capacity of 300 cm, flow 10 cmwater, 10 cmof hydrochloric acid solution and the dissolution of lead initially at room temperature and then under heating on an electric stove. After complete dissolution of batches in each glass add 3−4 drops of nitric acid and boil for 1−2 min. the Solutions were cooled to room temperature and transferred to volumetric flasks with a capacity of 50 cm.

In five out of six volumetric flasks, solutions of the sample, add 0,5; 1,0; 1,5; 2,0; 2,5 cmstandard solution B, which corresponds to the mass concentration of added manganese 0,05; 0,10; 0,15; 0,20; 0,25 µg/cm.

The solutions in all flasks is poured to the mark with water and mix.

To prepare the solution in the reference experiment in a beaker with a capacity of 300 cmis placed 10 cmwater, 10 cmof hydrochloric acid, heated to boiling, add 3−4 drops of nitric acid and boil for 1−2 min. the Solution was cooled to room temperature, transferred to a volumetric flask with a capacity of 50 cm, made up to the mark with water and mix.

Microspace injected into the graphite cuvette sequentially a solution of the reference experiment, the sample solution and in ascending concentrations of manganese solutions containing additives of a standard solution of manganese. Measurement of atomic absorption of manganese is carried out in the mode:

type of atomization is electro;

the current of the lamp, mA — 7,5;

wavelength, nm — 279,5;

the slot width of the device, nm — 0,4;

the drying temperature of the first stage, 353−393;

Stage II, 393−473;

the drying time stage I, 5;

II stage — 5;

the temperature of the ashing stage I, 473−773;

Stage II, 773−1273;

time ashing stage I, 5;

II stage — 5;

the temperature of the atomization, K — 2873;

the time of atomization, with — 5;

cleaning temperature, K — 2873;

cleaning — 2;

the speed of the argon cm/min — 200.

At the stage of atomization, the argon flow is stopped.

From the values of atomic absorption solutions containing additives of a standard solution of manganese, subtract the value of atomic absorption of the sample solution. According to the obtained values of the difference between of atomic absorption and corresponding mass concentrations of added manganese in µg/cmbuild a calibration curve, which find mass concentration of manganese in solution in the reference experiment and

sample.

3.3.2 In the case when the instrument is in automatic mode and held its graduations, hinge samples weighing 0.5 g were placed in four glasses with a capacity of 300 cm, is poured 10 cmof water, 10 cmof hydrochloric acid solution and then spend the dissolution as specified in 3.3.1. The solutions were transferred to volumetric flasks with a capacity of 50 cm.

In three of the four volumetric flasks with a solution of the sample add 0,5; 1,5; 2,5 cmstandard solution B, which corresponds to the mass concentration of added manganese 0,05; 0,15; 0,25 µg/cm.

The solutions in all flasks is poured to the mark with water and mix.

The solution in the reference experiment prepared as described in 3.3.1.

Microspace introduced into a graphite cuvette and the sample solution, and then in ascending concentrations of manganese solutions containing additives of a standard solution of manganese, carried out the calibration of an instrument. Measurement of atomic absorption of manganese is carried out in a mode on 3.3.1.

Then injected into the graphite cuvette, the solutions in the reference experiment and the sample and hold measurement of atomic absorption of manganese in mode on 3.3.1.

After every 4−5 measurements of atomic absorption graphite cuvette clear: microspace introduce water into it and carry out the process of atomization mode on 3.3.1.

3.4 Processing of analysis results

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

, (2)

where is the mass concentration of manganese in the sample solution, µg/cm;

 — mass concentration of manganese in solution in the reference experiment, µ g/cm;

 — the volume of the sample solution, cm;

 — weight of charge, g

.

3.4.2 Standards of accuracy of analysis results

The value of the tolerance definitions: permitted discrepancies in the results of parallel measurements (the rate of convergence) and the results of the analysis for the same samples, obtained in two laboratories or in the same, but in different conditions (a measure of reproducibility), and the margins of error definitions ( — accuracy rate) at a confidence level =0.95 is shown in table 3.

Table 3

Mass fraction of manganese, %	Characteristics error definitions %
Between 0.0005 and 0.0015 incl.	0,0002	0,0003	0,0002
SV. 0,0015 «0,0025 «	0,0005	0,0007	About 0.0006

3.4.3 Control of accuracy of analysis results

Control of accuracy of analysis results is carried out according to state standard sample in accordance with GOST 25086.

4 Atomic absorption method for the determination of manganese at a mass fraction of from 0.002 to 0.05%

4.1 the essence of the method

The method is based on measuring atomic absorption of manganese in the flame acetylene-air at a wavelength of 279.5 nm.

4.2 Equipment, reagents and solutions

Spectrophotometer of atomic absorption with the excitation source spectral lines of manganese.

Acetylene — GOST 5457.

Nitric acid — according to GOST 11125, diluted 1:1.

Hydrochloric acid — according to GOST 14261, diluted 1:1 and 1:99.

Manganese metal brands Мп00 — according to GOST 6008.

State standard samples made in accordance with GOST 8.315.

Standard solutions of manganese:

Solution a: prepare for 3.2.

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; prepare before use.

1 cmof a solution contains 0.01 mg of manganese.

4.3 analysis

4.3.1 Sample mass of 0.5 g was placed in a beaker with a capacity of 300 cm, is poured 10 cmof water, 10 cmof hydrochloric acid (1:1) and further conducting the dissolution as described in 3.3.1. The solution was transferred to volumetric flask with a capacity of 50 cm, made up to the mark with water and mix.

The solution in the reference experiment prepared as described in 3.3.1.

The solutions in the reference experiment and the sample is sprayed into the flame of acetylene-air and measure the atomic absorption at a wavelength of 279.5 nm.

Before measurement is carried out construction of calibration curve or the calibration of an instrument if it is running in automated mode.

4.3.2 Construction of calibration graphs

When the mass fraction of manganese, from 0.002 to 0,010% in five out of six volumetric flasks with a capacity of 50 cmis placed 1,0; 2,0; 3,0; 4,0; 5,0 cmstandard solution B, which corresponds to the mass concentration of manganese 0,2; 0,4; 0,6; 0,8; 1,0 µg/cm. The sixth solution of the flask is a solution of the reference experiment.

When the mass fraction of manganese from 0.01 to 0.05% in five out of six volumetric flasks with a capacity of 50 cmis placed 0,5; 1,0; 1,5; 2,0; 2,5 cmstandard solution A, which corresponds to mass concentrations of 1,0; 2,0; 3,0, 4,0; 5,0 mg/cm. The sixth solution of the flask is a solution of the reference experiment.

The solutions in all flasks is poured a solution of hydrochloric acid (1:99) to the mark, stirred, is sprayed into the flame of acetylene-air and measure the atomic absorption at a wavelength of 279.5 nm.

According to the obtained values of atomic absorption and corresponding mass concentrations of manganese in µg/cmbuild calibration charts in accordance with GOST 25086

.

4.3.3 calibration of the spectrophotometer

When the mass fraction of manganese, from 0.002 to 0,010% in three of the four volumetric flasks with a capacity of 50 cmis placed 1,0; 3,0; 5,0 cmstandard solution B, which corresponds to the mass concentration of manganese 0,2; 0,6; 1,0 µg/cm. The solution to the fourth flask is a solution of the reference experiment.

When the mass fraction of manganese from 0.01 to 0.05% in three of the four volumetric flasks with a capacity of 50 cmis placed 0,5; 1,5; 2,5 cmstandard solution A, which corresponds to the mass concentration of manganese 1,0; 3,0; 5,0 mg/cm. The solution to the fourth flask is a solution of the reference experiment.

The solutions in all flasks is poured a solution of hydrochloric acid (1:99) to the mark, stirred, is sprayed into the flame of acetylene-air, in sequence: a solution of the reference experiment and the standard solutions in ascending concentrations of manganese and conduct a calibration of an instrument. Measurement of atomic absorption is carried out at a wavelength of 279.5 nm.

4.4 Processing of analysis results

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

, (3)

where is the mass concentration of manganese in the sample solution, µg/cm;

 — mass concentration of manganese in solution in the reference experiment, µ g/cm;

 — the volume of the sample solution, cm;

 — weight of charge, g

.

4.4.2. Standards of accuracy of analysis results

The values of the characteristics of error definitions: permitted discrepancies in the results of parallel measurements (the rate of convergence) and the results of the analysis for the same samples, obtained in two laboratories or in the same, but in different conditions (a measure of reproducibility), and the margins of error definitions ( — accuracy rate) at a confidence level =0.95 is shown in table 4.

Table 4

Mass fraction of manganese, %	Characteristics error definitions %
From 0.002 to 0.004 incl.	0,001	0,0015	0,0012
SV. Of 0.004 «to 0.015 «	0,002	0,0030	0,0025
«0,015» 0,050 «	0,003	0,0045	0,0035

4.4.3 Control of accuracy of analysis results

Control of accuracy of analysis results is carried out according to state standard sample in accordance with GOST 25086.

Allowed to monitor the accuracy of analysis results by the method of additives in accordance with GOST 25086.

Additives is a standard solution A or B.