GOST 851.4-93

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  ГОСТ 851.4-93

GOST 851.4−93 Magnesium primary. Methods for determination of copper

GOST 851.4−93

Group B59

INTERSTATE STANDARD

MAGNESIUM PRIMARY

Methods for determination of copper

Primary magnesium.
Methods for determination of copper

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 75 interstate standard GOST 851.4−93 introduced directly as state standard of the Russian Federation from January 1, 1997

4 REPLACE GOST 851.4−87

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; 5.2; 6.2
GOST 61−75	4.2
GOST 199−78	4.2
GOST 859−2001	2.2; 3.2; 4.2; 5 2; 6.2
GOST 2603−79	2.2
GOST 3118−77	3.2; 4.2
GOST 3760−79	3.2; 4.2
GOST 3773−72	3.2
GOST 4328−77	2.2
GOST 4461−77	2.2; 3.2
GOST 5456−79	4.2
GOST 5457−75	6.2
GOST 5845−79	4.2
GOST 6552−80	2.2
GOST 6709−72	5.2
GOST 10157−79	5.2
GOST 11125−84	5.2; 6.2
GOST 14261−77	2.2; 5.2; 6.2
GOST 18300−87	3.2
GOST 25086−87	1.1; 1.4; 2.3.2; 2.4.3; 3.3.2; 3.4.3; 4.3.2; 4.4.3; 5.4.3; 6.3.2; 6.4.3
THAT 6−09−01−768−89	3.2
THAT 6−09−09−566−75	3.2
THAT 6−09−07−1440−84	2.2
THAT 6−09−07−1634−87	3.2
THAT 6−09−50−5437−88	4.2
THAT 6−09−1181−89	2.2
THAT 6−09−11−1203−79	4.2
THAT 6−09−3973−75	3.2

This standard specifies the photometric (with mass fraction of copper from 0,0003% to 0.05%) and atomic absorption (at a mass fraction of copper from 0.0005% to 0.05%) methods for determination of copper 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 copper 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, specify the method of determining, and method and results of control accuracy.

2 the Photometric method for the determination of copper with the use of 1,5-di-(2-hydroxy-4-nitrophenyl)-3-acetylpromazine

2.1 the essence of the method

The method is based on formation of soluble in aqueous-acetone medium is colored in blue color complex compounds of copper with 1,5-di-(2-hydroxy-4-nitrophenyl)-3-acetylpromazine and subsequent measurement of optical density of the solution.

2.2 the Instrument, reagents and solutions

Spectrophotometer.

Electromagnetic stirrer.

Universal indicator paper, pH 1:10 — on the other 6−09−1181.

Hydrochloric acid — according to GOST 14261, diluted 1:1 and the solution with a molar concentration of 0.5 mol/DM.

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

Orthophosphoric acid — according to GOST 6552, solution with molar concentration of 1 mole/DM.

Sodium hydroxide — GOST 4328, a solution with a mass concentration of 100 g/cm.

Acetone — GOST 2603.

1,5-di-(2-hydroxy-4-nitrophenyl)-3-acetylfuran — on the other 6−09−07−1440, a solution with a mass concentration of 0.25 g/l: 0.025 g 1,5-di-(2-hydroxy-4-nitrophenyl)-3-acetylpromazine dissolved in 70−80 cmof acetone with stirring using an electromagnetic stirrer, made up to a volume of 100 cmof acetone and then mixed.

Copper brand MO — according to the GOST 859.

State standard samples made in accordance with GOST 8.315.

Water bidistilled.

Standard solutions of copper:

Solution a: 1.0 g of copper metal is dissolved in nitric acid solution, and remove the oxides of nitrogen by boiling, cooled to room temperature, transferred into 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 the solution contains 1 mg of copper.

Solution B: 2 cmof solution A is poured into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix; prepare before use.

1 cmof a solution contains 0.002 mg

copper.

2.3 analysis

2.3.1 Sample weight of 0.5−2.0 g (table 1) were placed in a glass with a capacity of 200 cmand is dissolved in 30−40 cmof hydrochloric acid (1:1), Prilepa his portions at 2−3 cm. The dissolution of lead initially at room temperature, and after violent reaction when heated. After complete dissolution of the sample solution is evaporated to a thick syrup. The solution in the reference experiment evaporated to dryness. Then the residue is dissolved in 10−20 cmof water when heated, transferred to a volumetric flask with a capacity of 50 cm, made up to the mark with water and mix.

Aliquot part of the solution (see table 1) placed in a volumetric flask with a capacity of 50 cm, set pH 4−5 with a solution of sodium hydroxide according to the universal paper, add 4 cmof a hydrochloric acid solution with a molar concentration of 0.5 mol/DM, 2 cmof a solution of phosphoric acid, 30 cmof acetone, 2 cmof a solution of 1,5-di-(2-hydroxy-4-nitrophenyl)-3-acetylpromazine, made up to the mark with water and mix. After 15 min measure the optical density of the solution at a wavelength of 640 nm. Solution comparison is the solution of the reference experiment.

Table 1

Mass fraction of copper, %	The mass of charge, g	Aliquota part of the solution, see
From the 0.0003 to 0.001 incl.	2,0	10
SV. 0,0010 «0,004 «	2,0	5
«0,0040» 0,010 «	1,0	2
«0,0100» 0,050 «	0,5	2

2.3.2 Construction of calibration curve

To build a calibration curve in six of the seven volumetric flasks with a capacity of 50 cmplaced 0,5; 1,0; 2,0; 4,0; 6,0; 8,0 cmstandard solution B, which corresponds to 0,001; 0,002; 0,004; 0,008; 0,012; 0,016 mg of copper. A seventh solution of the flask is a solution of the reference experiment. To each flask add 4 cmof a hydrochloric acid solution with a molar concentration of 0.5 mol/cmand then do 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 copper () in percent is calculated by the formula

, (1)

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

 — total volume of sample solution, cm;

 — the mass of sample, g;

 — volume aliquote parts of a solution of the sample, cm.

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 copper, %	Characteristics error definitions %
From the 0.0003 to 0.001 incl.	0,00015	0,00020	0,00016
SV. 0,0010 «0,003 «	0,00040	0,00060	0,00050
«0,0030» 0,010 «	0,00100	0,00150	0,00120
«0,0100» 0,030 «	0,00200	0,00300	0,00200
«0,0300» 0,050 «	0,00500	0,00700	0,00600

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.

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

Additives is a standard solution A.

3 Photometric method for the determination of copper with the use of accelerated

3.1 the essence of the method

The method is based on formation of colored Magenta complex compounds of copper with acetyldihydrocodeine and subsequent measurement of optical density of the solution.

3.2 Equipment, reagents and solutions

The spectrophotometer or photoelectric colorimeter.

Hydrochloric acid — according to GOST 3118, diluted 1:1.

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

Ammonia water according to GOST 3760, diluted 1:1.

Ammonium citrate — on the other 6−09−01−768, a solution with a mass concentration of 400 g/DM.

Ethyl alcohol — GOST 18300, the solution with the mass concentration of 960 g/DM.

Neutral red on the other 6−09−07−1634, a solution with a mass concentration of 1 g/lin ethanol.

Para-NITROPHENOL — on the other 6−09−3973, a solution with a mass concentration of 0.5 g/DM.

Ammonium chloride — GOST 3773, a solution with a mass concentration of 200 g/DM.

Buffer solution with a pH of 9.9: 500 cmof a solution of ammonium chloride is mixed with 500 cmof a solution of ammonia.

Acetic aldehyde, a solution with a mass concentration of 400 g/DM: in a volumetric flask with a capacity of 1000 cmis placed 500 cmof water, cooled to a temperature To 278−283, slowly poured in small portions of the chilled ampoule 400 g of acetaldehyde and stirred and cooled the flask in ice water. Topped up to the mark with water and mix. All operations are performed in a fume hood.

Oxalidaceae — on the other 6−09−09−566, a solution with a mass concentration of 2.5 g/DM: 2.5 g oxalidaceae dissolved in water, heated to a temperature of 313−323 K, cool, add water to 1000 cmand mixed.

Copper brand MO — according to the GOST 859.

State standard samples made in accordance with GOST 8.315.

Standard solutions of copper:

Solution a: prepared according to 2.2.

Solution B: 5 cmsolution And placed in a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix; prepare before use.

1 cmof a solution contain 0,005

mg of copper.

3.3 analysis

3.3.1 the sample weighing 1.0 g was placed in a beaker with a capacity of 300 cm, moistened with water and dissolved in 15 cmof a hydrochloric acid solution. After dissolving the sample, add 3−4 drops of nitric acid and boil to remove oxides of nitrogen and excess acidity (up to about volume 10 cm). The resulting solution was transferred to a volumetric flask with a capacity of 50 cm(at a weight ratio of copper to 0.003%) or 100 cm(for the mass concentration of copper in excess of 0.003%), made up to the mark with water and mix. Aliquot part of a solution containing from 2.5 to 15 micrograms of copper, placed in a volumetric flask with a capacity of 50 cm, add 5 cmof ammonium citrate solution, 1 drop of solution of neutral red or paranitrophenol. Neutralized with ammonia solution until the colour yellow, add 5 cmof acetic aldehyde, 10 cmbuffer solution, 5 cmsolution oxalidaceae, made up to the mark with water and mix. After 15 min measure the optical density of the solution at a wavelength of 540 nm.

Solution comparison is the solution of the control op

it.

3.3.2 Construction of calibration curve

To build a calibration curve in six of the seven volumetric flasks with a capacity of 50 cmplaced 0,5; 1,0; 1,5; 2,0; 2,5; 3,0 cmstandard solution B, which corresponds to 0,0025; 0,0050; 0,0075; 0,0100; 0,0125; 0,0150 mg of copper. A seventh solution of the flask is a solution of the reference experiment. To each flask add 5 cmof a solution of citrate of ammonium and then do as specified in 3.3.1.

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.

3.4 Processing of analysis results

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

, (2)

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

 — total volume of sample solution, cm;

 — the mass of sample, g;

 — volume aliquote parts of a solution of the sample, cm.

3.4.2 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 3.

Table 3

Mass fraction of copper, %	Characteristics error definitions %
To from 0,0005 0,0010 incl.	0,0002	0,0003	0,0002
SV. 0,0010 «0,0050 «	0,0004	About 0.0006	0,0005
«0,0050» 0,0100 «	0,0010	0,0015	0,0012

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.

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

Additives is a standard solution B.

4 Photometric method for the determination of copper with the use of 2,2'-bicinchoninic acid

4.1 the essence of the method

The method is based on formation of colored in red-violet color complex copper compounds with 2,2'-bicinchoninic potassium and subsequent measurement of optical density of the solution.

4.2 Equipment, reagents and solutions

The spectrophotometer or photoelectric colorimeter.

Hydrochloric acid — according to GOST 3118, diluted 1:1.

Ammonia water according to GOST 3760, a solution with a mass concentration of 100 g/DM.

Hydroxylamine hydrochloric acid — according to GOST 5456, solution with a mass concentration of 100 g/DM.

Potassium-sodium vinocity — GOST 5845, solution with the mass concentration of 500 g/DM.

Potassium hydroxide on the other 6−09−50−5437, a solution with a mass concentration of 20 g/DM.

2,2'-bicinchoninic acid on the other 6−09−11−1203.

2,2'-bicinchoninic potassium, a solution with a mass concentration of 1 g/DM: 0.1 g 2,2'-bicinchoninic acid are dissolved in 100 cmof solution of potassium hydroxide.

Acetic acid — according to GOST 61, solution with molar concentration of 2 mol/DM.

Sodium acetate — GOST 199, solution with molar concentration of 2 mol/DM.

Buffer solution with a pH of 6: in a volumetric flask with a capacity of 500 cmare placed 33 cmof acetic acid, add a solution of sodium acetate to the mark and mix.

Copper brand MO — according to the GOST 859.

State standard samples made in accordance with GOST 8.315.

Standard solutions of copper:

Solution a: prepared in accordance with 2.2.

Solution B: 10 cmsolution And placed in a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix; prepare before use.

1 cmof a solution contains 0.01 m

g of copper.

4.3 analysis

4.3.1 Sample mass 1.0 g are placed in a beaker with a capacity of 100 cm, moistened with water and dissolved in 20 cmof a hydrochloric acid solution.

After complete dissolution of the sample solution is evaporated to a volume of 10 cm, cooled to room temperature and transferred to a volumetric flask with a capacity of 50 cm. Then add 1 cmof a solution of hydrochloric acid hydroxylamine, 2 cmof mortar Vinokurova potassium-sodium, neutralized with ammonia solution on the paper «Congo», add a 5 cmbuffer solution, 2 cmof a solution of 2,2'-bicinchoninic potassium, made up to the mark with water and mix. After 10 minutes measure the optical density of the solution at a wavelength of 560 nm.

Solution comparison is the solution, the control experience

.

4.3.2 Construction of calibration curve

To build a calibration curve in five out of six volumetric flasks with a capacity of 50 cmis placed 0,5; 1,0; 2,0; 3,0; 4,0 cmstandard solution B, which corresponds to 0,005; 0,010; 0,020; 0,030; 0,040 mg of copper. The sixth solution of the flask is a solution of the reference experiment. To all flasks add 1 cmof a solution of hydrochloric acid hydroxylamine, 2 cmof mortar Vinokurova potassium-sodium and then do as specified in 4.3.1.

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.

4.4 Processing of analysis results

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

, (3)

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

 — the weight of the portion,

4.4.2 Standards of accuracy of analysis results

The values of the error characteristics of definitions: permitted discrepancies in the results of parallel measurements: ( — an indicator 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 4.

Table 4

Mass fraction of copper, %	Feature definition error, %
From 0,0010 to 0,0050 incl.	0,0005	0,0007	About 0.0006
SV. 0,0050 «0,0100 «	0,0010	0,0015	0,0012

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 B.

5 Atomic absorption method for the determination of copper when the mass fraction of from 0.0005 to 0.0025%

5.1 the essence of the method

The method is based on measuring atomic absorption of copper at a wavelength of 324,8 nm in the electrothermal atomization mode.

The determination is carried out by standard addition.

5.2 the Instrument, reagents and solutions

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

Microspec with a capacity of 2 µm.

Argon — GOST 10157.

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

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

State standard samples made in accordance with GOST 8.315.

Copper brand MO — according to the GOST 859.

Bidistilled water — according to GOST 6709.

Standard solutions of copper:

Solution a: 0,100 g of copper is dissolved in 10 cmof nitric acid solution, pour 10 cmof hydrochloric acid (1:1) and boiled for 10 min. 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; fit for use for 6 months.

1 cmof solution A contains 0.1 mg of copper.

Solution B: 5 cmsolution And poured into a volumetric flask with a capacity of 100 cm, is poured a solution of hydrochloric acid (1:99) to the mark and mix; prepare before use.

1 cmof solution B contains 5 µg of med

I.

5.3 analysis

5.3.1 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 (1:1) and lead dissolution 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 with a solution 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 copper 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 cmpour 10 cmof water, 10 cmof hydrochloric acid (1:1), heated to boiling, add 3−4 drops of nitric acid and boil for 1−2 min. the solution was Then 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 copper solutions containing additives of a standard solution of copper. Measurement of atomic absorption of copper is carried out in the mode:

type of atomization is electro;

the current of the lamp, mA — 7,5;

wavelength, nm — 324,8;

the slot width of the device, nm — 1,3;

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, 473−873;

Stage II, 873−1273;

time ashing stage I, 5;

II stage — 5;

the temperature of the atomization, the K — 2823;

the time of atomization, with — 5;

cleaning temperature, K — 2823;

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 copper, 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 copper in µg/cmbuild a calibration curve, which find mass concentration of copper in solution in the reference experiment and

sample.

5.3.2 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, flow 10 cmwater, 10 cmof hydrochloric acid (1:1) and further conducting the dissolution as described in 5.3.1. 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 copper 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 5.3.1.

Microspace introduced into a graphite cuvette and the sample solution, and then, in ascending order of concentration of copper, solutions containing additives of a standard solution of copper, carried out the calibration of an instrument.

Measurement of atomic absorption of copper is carried out in the regime 5.3.1.

Then injected into the graphite cuvette, the solutions in the reference experiment and the sample and hold measurement of atomic absorption of copper in the regime 5.3.1.

After every 4−5 measurements of atomic absorption clean the graphite cuvette: microspace introduce water into it and spend the atomization process in the regime 5.3.1.

5.4 Processing of analysis results

5.4.1 Mass fraction of copper () in percent is calculated by the formula

, (4)

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

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

 — the volume of the sample solution, cm.

 — mass of test portions, g

.

5.4.2 Norms 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 5.

Table 5

Mass fraction of copper, %	Characteristics error definitions %
Between 0.0005 and 0.0015 incl.	0,0002	0,0003	0,0002
SV. 0,0015 «0,0025 «	0,0005	0,0008	About 0.0006

5.4.3 Control of accuracy of analysis results

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

6 Atomic absorption method for the determination of copper when the mass fraction of from 0.002 to 0.050%

6.1 the essence of the method

The method is based on measuring atomic absorption of copper in the flame acetylene-air at a wavelength of 324,8 nm.

6.2 Apparatus, reagents and solutions

Spectrophotometer of atomic absorption with excitation sources spectral lines of copper and silver (or molybdenum).

Copper brand MO — according to the GOST 859.

Acetylene — GOST 5457.

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

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

State standard samples made in accordance with GOST 8.315.

Standard solutions of copper:

Solution a: prepared according to 5.2.

Solution B: 10 cmsolution And placed in a volumetric flask with a capacity of 100 cm, is poured a solution of hydrochloric acid (1:99) to the mark and mix; prepare before use.

1 cmof a solution contains 0.01 mg of copper.

6.3 analysis

6.3.1 Sample weight 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 then produce a dissolution as specified in 5.3.1. The solution was transferred to volumetric flask with a capacity of 50 cm.

The solution in the reference experiment prepared as described in 5.3.1.

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 324,8 nm.

Before measuring the atomic absorption of the sample solutions and control experience to produce the construction of calibration curve or the calibration of an instrument if it is running in automated mode.

6.3.2 Construction of calibration graphs

When the mass fraction of copper 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 copper 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 copper 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 the mass concentration of copper 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 324,8 nm.

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

.

6.3.3 calibration of the spectrophotometer

When the mass fraction of copper 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 copper 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 copper 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 copper 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 copper and carried out the calibration of an instrument. Measurement of atomic absorption is carried out at a wavelength of 324,8 nm.

6.3.4 In the case when the device does not carry out the correct background, after measuring the atomic absorption of copper in the solutions of sample and reference experiment replace the source of excitation of spectral lines of the copper on the source of excitation of spectral lines of silver or molybdenum and sprayed solutions of sample and reference experiment in the flame acetylene-air. Measurement of atomic absorption is carried out at a wavelength of 328 nm for silver or 313 nm for molybdenum. Received signals of atomic absorption is subtracted respectively from values of atomic absorption of copper in solutions of the sample and the reference experiment.

6.4 Processing the results of the analysis

6.4.1 Mass fraction of copper () in percent is calculated by the formula

, (5)

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

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

 — the volume of the sample solution, cm;

 — weight of charge, g

.

6.4.2 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 6.

Table 6

Mass fraction of copper, %	Characteristics error definitions %
From 0,002 to 0,006 incl.	0,0005	0,0008	About 0.0006
SV. 0,006 «0,020 «	0,0015	0,0023	0,0020
«0,020» 0,050 «	0,0040	0,0060	0,0050

6.4.3 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 B.