GOST 3240.12-76

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  ГОСТ 3240.12-76

GOST 3240.12−76 magnesium Alloys. Methods for determination of copper (with Change No. 1)

GOST 3240.12−76

Group B59

INTERSTATE STANDARD

MAGNESIUM ALLOYS

Methods for determination of copper

Magnesium alloys
Methods for determination of copper

ISS 77.120.20
AXTU 1709

Date of introduction 1978−01−01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of aviation industry of the USSR

2. APPROVED AND promulgated by the Decree of the State Committee of standards of Ministerial Council of the USSR from 28.12.76 N 2889

3. REPLACE GOST 3240−56 in part of sec. III

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

5. Limitation of actions taken by Protocol No. 2−92 of the Interstate Council for standardization, Metrology and certification (ICS 2−93)

6. EDITION with Change No. 1, approved in June 1987 (IUS 11−87)


This standard sets the photometric and atomic absorption methods for the determination of copper (at a mass fraction of copper from 0.001 to 0.8%).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 3240.0.

2. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF COPPER CONTENT

2.1. The essence of the method

The method is based on the formation of complex compounds of copper with biocatalogue-oxalidaceae at pH 7.8 to 9.8 and fotomaterialy color intensity of the obtained complex compound, painted in purple color, at 536 nm.

(Changed edition, Rev. N 1).

2.2. Apparatus, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

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

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

Ammonium citrate on the other 6−09−01−766 odnosemjannyj, 40% solution.

Rectified ethyl alcohol according to GOST 5962*.
________________
* On the territory of the Russian Federation GOST R 51652−2000.

Neutral red, a 0.01% alcoholic solution.

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

Ammonium chloride according to GOST 3773, 20% solution.

Buffer solution with a pH of 9.9 is prepared as follows: 500 cmof a solution of ammonium chloride is mixed with 500 cmof ammonia, diluted 1:1.

The acetic aldehyde, the solution is prepared as follows: into a measuring flask with volume capacity of 1000 cmmake 500 cmof water and slowly add in chilled under running water ampoules 400 cmof acetaldehyde, then topped to the mark with water and mix.

Oxalidaceae, 0,25% solution.

Magnesium chloride, solution; is prepared as follows: 210 g of magnesium chloride according to GOST 4209 dissolved in water, filtered through a filter of medium density in a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

1 cmof the solution contains 25 mg of magnesium.

Copper of mark M0 GOST 859.

Standard solutions of copper

Solution A, prepared as follows: 0.5 g of copper is dissolved in nitric acid, diluted 1:1, and remove the oxides of nitrogen by boiling, transfer the solution into a volumetric flask with a capacity of 500 cm, is diluted to the mark with water and mix.

1 cmof the solution contains 1 mg of copper.

Solution B is prepared as follows: 5 cmmortar And transferred to a volumetric flask with a capacity of 500 cm, is diluted to the mark with water and mix.

1 cmof a solution contains 0.01 m

g of copper.

2.3. Analysis

2.3.1. A sample of alloy weighing 1 g is placed in a beaker with a capacity of 400 cm, and dissolved in 20 cmof hydrochloric acid. To the solution was added 2−3 drops of nitric acid, boil to remove oxides of nitrogen, transferred to a volumetric flask with a capacity of 100 cm, is diluted to the mark with water and mix.

Depending on the mass fraction of copper taken for analysis in a volumetric flask with a capacity of 100 cmvarious aliquote part of the solution, given in table.1.

Table 1

Then pour 10 cmof ammonium citrate solution, two drops of neutral red, is neutralized with ammonia to the yellow color of the solution, add 10 cmof a solution of acetaldehyde and again to neutralize the yellow color of the solution.

The solution is thoroughly mixed, add 20 cmbuffer solution, 20 cmaccelerated solution, dilute to the mark with water and mix. After 15 min measure the optical density of a solution of 536 nm, using appropriate cuvettes.

Solution comparison is the solution of the reference experiment.

Mass fraction of copper found by the calibration schedule.

2.3.2. Construction of calibration curve

2.3.2.1. When the mass fraction of copper from 0.001 to 0.02%

Nine volumetric flasks with a capacity of 100 cm tomake 10 cmof a solution of magnesium chloride and 0; 0,25; 0,5; 1,0; 2,0; 3,0; 4,0; 5,0 and 6.0 cmof solution B, which corresponds to 0; 2,5·10; 5·10; 1·10; 2·10; 3·10; 4·10; 5·10and 6·10g of copper. Further analysis are as indicated in claim 2

.3.1.

2.3.2.2. When the mass fraction of copper from 0.02 to 0.16%

Nine volumetric flasks with a capacity of 100 cmmake 4 cmof a solution of magnesium chloride, and then sequentially 0; 2,0; 4,0; 6,0; 8,0; 10,0; 12,0; 14,0; 16,0 cmof solution B, which corresponds to 0; 2·10; 4·10; 6·10; 8·10; 1·10; 1,2·10; 1,4·10; 1.6 x 10g of copper. Further analysis are as indicated in claim 2

.3.1.

2.3.2.3. When the mass fraction of copper from 0.16 to 0.8%

Nine volumetric flasks with a capacity of 100 cmis administered by 1 cmof a solution of magnesium chloride, and then sequentially 0; 2,0; 4,0; 6,0; 8,0; 10,0; 12,0; 14,0; 16,0 cmof solution B, which corresponds to 0; 2·10; 4·10; 6·10; 8·10; 1·10; 1,2·10; 1,4·10; 1.6 x 10g of copper. Further analysis are as indicated in claim 2.3.1. On the found values of the optical densities of the calibration build Gras

fics.

2.3.2.1−2.3.2.3. (Changed edition, Rev. N 1).

2.4. Processing of the results

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

,

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

 — volume of initial solution, cm;

 — volume aliquote part of the solution, cm;

 — the weight of the portion of alloy,

(Changed edition, Rev. N 1).

2.4.2. Allowable absolute differences of the results of the parallel definitions should not exceed the values given in table.2.

Table 2

2.5. Control of measurement accuracy

To control the accuracy of the measurements the mass fraction of copper from 0.001 to 0.8% use state standard samples of magnesium alloys, as well as industry standard samples and standard samples of the enterprise of magnesium alloys, issued in accordance with GOST 8.315. Accuracy control measurement is carried out in accordance with GOST 25086.

Allowed to monitor the accuracy of the measurements the mass fraction of copper by a method of additives.

(Added, Rev. N 1).

3. ATOMIC ABSORPTION METHOD FOR THE DETERMINATION OF COPPER CONTENT

3.1. The essence of the method

The method is based on measuring atomic absorption of copper at a wavelength of 324,7 them in the flame acetylene-air.

3.2. Apparatus, reagents and solutions

Spectrophotometer atomic absorption.

Nitric acid according to GOST 11125, OS.CH., diluted 1:1.

Hydrochloric acid according to GOST 14261, OS.CH., diluted 1:1.

Bidistilled water, obtained according to GOST 4517.

Primary magnesium ingots according to GOST 804 brand Мг96 in the form of chips.

A solution of magnesium 50 g/DM: 50 g of magnesium was dissolved in 800 cmof a hydrochloric acid solution, transferred to a volumetric flask with a capacity of 1 DM, dilute to the mark with water and mix.

Copper metal according to GOST 859 in the form of chips.

Standard solutions of copper

Solution a: 1 g of copper is dissolved in 50 cmof a solution of nitric acid with gentle heating. Upon completion of the dissolution solution is transferred to a volumetric flask with a capacity of 1 DM, dilute to the mark with water and mix.

1 cmof the solution contains 0.001 g of copper.

Solution B: 10 cmsolution And transferred to a volumetric flask with a capacity of 100 cm, is diluted to the mark with water and mix.

1 cmof a solution contains 0.0001 g of copper.

Acetylene in cylinders GOST 54

57.

3.1; 3.2. (Changed edition, Rev. N 1).

3.3. Analysis

3.3.1. A portion of the sample weighing 2 g were placed in a glass with a capacity of 400 cm, carefully dissolved in 30−35 cmof a hydrochloric acid solution, add 5−10 drops of nitric acid, boil to remove oxides of nitrogen. The solution was cooled, transferred to a volumetric flask with a capacity of 50 cm, made up to the mark with water and mix.

When the mass fraction of copper from 0.1 to 0.5% aliquot part of the solution was 10 cm,transferred to a volumetric flask with a capacity of 50 cm, made up to the mark with water and mix. Parallel to the sample conduct analysis of control experience.

Measure the atomic absorption of copper in the sample solution, the solution control experience and solutions to build the calibration curve in atomic absorption spectrophotometer against water at a wavelength of 324,7 nm in the flame acetylene-air.

Mass fraction of copper in the sample solution and the reference experiment is determined by the calibration schedule.

3.3.2. Construction of calibration curve

To construct the calibration curve in mass fraction of copper from 0.001 to 0.1% in a series of volumetric flasks with a capacity of 50 cmis administered at 40 cmof a solution of magnesium, 0; 0,2; 0,5; 1,0; 2,0 and 5.0 cmof solution B and 1.0; 2.0 cmof solution A, which corresponds to 0; 0,02; 0,05; 0,10; 0,20; 0,50; 1,0 and 2.0 mg of copper, dilute to the mark with water and mix.

When the mass fraction of copper from 0.1 to 0.5% in different series of volumetric flasks with a capacity of 50 cm8 cm injectedsolution of magnesium, 0; 4,0; 10,0; 20,0 cmof solution B, which corresponds to 0; 0,4; 1,0 and 2,0 mg of copper, dilute to the mark with water, mix and measure the atomic absorption of copper according to claim 3.3.1.

From the obtained values of atomic absorption solutions to build calibration curve

.

3.3.1; 3.3.2. (Changed edition, Rev. N 1).

3.4. Processing of the results

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

,

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

 — the mass of copper in solution in the reference experiment, was found in the calibration schedule g;

 — the weight of the portion of sample taken for spectrophotometry,

3.4.2. Allowable absolute differences of the results of the parallel definitions should not exceed the values given in table.3.

Table 3

3.4.1; 3.4.2. (Changed edition, Rev. N 1).

3.5. Control of measurement accuracy

Accuracy control measurement is carried out according to claim 2.5.

(Added, Rev. N 1).