GOST 13938.1-78

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  ГОСТ 13938.1-78

GOST 13938.1−78 Copper. Methods for determination of copper (with Amendments No. 1, 2, 3, 4)

GOST 13938.1−78

Group B59

INTERSTATE STANDARD

COPPER

Methods for determination of copper

Copper. Methods for determination of copper

AXTU 1709

Date of introduction 1979−01−01

INFORMATION DATA

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

DEVELOPERS

G. P. Giganov; E. M. Peneva; A. A. Blyahman; E. D. Shuvalov, A. N. Savelieva

2. APPROVED AND promulgated by the Decree of the State Committee of standards of Ministerial Council of the USSR from 24.01.78 N 155

3. REPLACE GOST 13938.1−68

4. The standard corresponds to the international standard ISO 1553−76

5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

6. Limitation of actions taken by Protocol No. 3−93 Interstate Council for standardization, Metrology and certification (ICS 5−6-93)

7. REPRINT (October 1999) with Amendments No. 1, 2, 3, 4, approved in March 1979, April 1983, June 1985, April 1988 (IUS 5−79, 7 to 83, 8−85, 7−88)


This standard specifies the electrolytic weighting and calculation methods for determination of copper.

The method is based on the electrolytic release of copper from a solution of sulfuric and nitric acids in the presence of ammonium salts at a platinum mesh electrode at a current density of 2−3 A/DMand voltage of 2.2−2.5 V.

The copper remaining in the electrolyte is determined by atomic absorption or photometric method to form colored complex compounds with cuprizone or diethyldithiocarbamate lead, in case of disagreement in the assessment of mass fraction of copper.

When the mass fraction of copper from a 99.0 to 99.9% copper in the amount of silver is determined electrolytically.

Mass fraction of copper above the 99.9% determined by difference, subtracting the amount of certain impurities from 100%.

(Changed edition, Rev. N 1, 2, 4).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 25086 with additions.

1.1.1. The selection and preparation of samples of copper to the analysis carried out according to GOST 24231, GOST 546* or GOST 193.
______________
* On the territory of the Russian Federation GOST 546−2001. — Note the manufacturer’s database.

1.1.2. Mass fraction of copper is determined in parallel in three batches, impurities in two. Simultaneously with the analysis performed by two control expertise to make the result of the analysis corrections for contamination of the reagents by subtracting the value of the reference experience from the result of the determination of a component in the analysis sample.

1.1.3. For the results of the analysis are in electrogravitational method for determination of copper the arithmetic mean of three parallel definitions, calculation method for determination of copper and the determination of impurities in copper — the arithmetic mean of two parallel definitions.

The numerical values of analysis results needs to contain the last significant digit in the same category, which is the last significant digit of the numerical value of the admitted discrepancies in the results definitions.

1.1.4. Control of the correctness of the results of the analysis carried out on standard samples of composition of copper or the method of additions.

1.2. Security requirements for the determination of copper and impurities in copper

1.2.1. All the operations of chemical analysis related to the release of toxic fumes or gases be installed in boxes equipped with local suction device.

1.2.2. Jobs to perform analyses must be organised in accordance with the requirements of GOST and GOST 12.2.032 12.2.033; laboratory premises equipped with ventilation systems according to GOST 12.4.021.

1.2.3. When performing analysis of copper in the workplace air can be harmful substances, maximum permissible concentration (MPC according to GOST 12.1.005), and the hazard class prescribed by GOST 12.1.007, given in the table.

1.2.4 Monitoring of content of harmful substances in the air of working zone according to GOST 12.1.007, according to the methods of determination of harmful substances in the air of working zone, approved by the USSR Ministry of health.

1.2.5. Disposal analysis is carried out in accordance with the rules of surface water protection from pollution by sewage, approved by the USSR Ministry of health.

Waste acid and alkali should be collected separately in special collections. Before discharge to sewer they must be neutralized.

Use, removal and disposal of cyanide compounds, arsenic anhydride, mercury must be in accordance with the sanitary rules of design, equipment and maintenance of warehouses for storage of highly toxic substances approved by USSR Ministry of health.

1.2.6. Laboratory facilities in which the work is performed according to the chemical analysis of the investigated material, explosive, explosive-fire and fire hazard classified industries with flammable fluids, and fire safety requirements they need to meet the requirements of GOST 12.1.004. The means and methods of fire suppression should be applied according to the GOST 12.4.009 depending on the origin and nature of the fire.

1.2.7. When working with gas installations should comply with the safety requirements according to GOST 12.2.008 and safety rules in the gas sector, approved by Gosgortekhnadzor of the USSR.

All electrical installations and electrical equipment used in laboratories when performing tests, shall conform to the requirements of GOST 12.2.007.0 and electrical codes adopted by the state energy supervision Committee of the USSR.

Sec. 1. (Changed edition, Rev. N 4).

2. APPARATUS, REAGENTS AND SOLUTIONS

Electrodes made of platinum mesh according to GOST 6563.

Installation for electrolysis with a stirrer.

Spectrophotometer or photoelectrocolorimeter with all accessories.

Spectrophotometer, atomic absorption, comprising a lamp with a hollow cathode made of copper, the burner for flame acetylene-air and spray system.

Acetylene according to GOST 5457.

Air compressor.

Drying oven with thermostat.

Nitric acid according to GOST 4461, diluted 1:1 and 1:20.

Sulfuric acid according to GOST 4204, and diluted 1:1.

The mixture for dissolution: 500 g of ammonium nitrate dissolved in 500 cmof water is added to 500 cmof nitric acid, 200 cmof sulphuric acid and add water to 2 DM.

Tartaric acid according to GOST 5817, a solution of 200 g/DM.

Citric acid according to GOST 3652.

Ammonia water according to GOST 3760, diluted 1:4.

Ammonium nitrate according to GOST 22867.

Ammonium citrate, solution; is prepared as follows: 150 g of citric acid dissolved in 400 cmof water, add 200 cmof solution of ammonia, cooled and made up to 1 DMwith water and stirred.

Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid 2-water (Trilon B) according to GOST 10651, 01 M solution: 37.2 g Trilon B dissolved in 800 cmof water and dilute with water to 1 DM.

Cuprizone, bis- (cyclohexanone) oxalidaceae, a solution of 2.5 g/DM: 2.5 g cuprizone dissolved with stirring in 900 cmof water at a temperature of 70−80 °C. After cooling, the solution was filtered into a vessel made of dark glass, top up with water to 1 DM, mixed and stored in this vessel.

The solution to fit the application within 10 days.

Sodium sulphate anhydrous according to GOST 4166.

Phenolphthalein (the indicator) at the NTD, solution in alcohol 1 g/DM.

Carbon tetrachloride according to GOST 20288.

Rectified ethyl alcohol according to GOST 18300.

Copper according to GOST 859*.
______________
* On the territory of the Russian Federation GOST 859−2001. — Note the manufacturer’s database.

Solutions of copper standard.

Solution A, prepared as follows: 0,500 g of copper is dissolved in 20 cmof the mixture to dissolve, and when heated removes the oxides of nitrogen. After cooling, dilute the solution with water to 100 cm, pour it into a measuring flask with a capacity of 1 DM, made up to the mark with water and mix.

1 cmof solution contains 0.5 mg of copper.

Solution B is prepared as follows: 20 cmsolution And placed in a volumetric flask with a capacity of 1 DM, add 5 cmof sulphuric acid diluted 1:1, made up to 1 DMwith water and stirred.

1 cmof the solution contains 0.01 mg of copper.

Universal indicator paper.

Diethyldithiocarbamate, lead (II) solution of 0.2 g/lin chloroform: 0,2 g of salt is placed in a measuring flask with volume capacity of 1000 cm, add 100−200 cmof chloroform, and stirred to dissolve the sample. Dilute with chloroform to the mark and mix again. The solution was stored in a flask made of dark glass in a dark place.

(Changed edition, Rev. N 2, 3, 4).

3. ANALYSIS

3.1. The weight of the electrolytic method of determining copper (at a mass proportion from a 99.0 to 99.9%)

3.1.1. A sample of copper with a mass of 1,0−2,0 g placed on the weighing pan, where it is weighed platinum cathode, designed for electrolysis, and determine the total mass of the cathode and copper. Allows for separate weighing of the sample of copper and a cathode, intended for electrolysis. A sample of copper is transferred to a beaker with a capacity of 250 cm, 40 cm, addthe mixture to dissolve and the glass cover watch glass. After dissolution of sample of copper the solution is gently heated to remove oxides of nitrogen, diluted to 180 cmof water, heated to 40 °C and into the solution immerse the platinum electrodes. This is followed by electrolysis for 2.5 h at a current density of 2−3 A/DMand voltage of 2.2−2.5 In, stirring the solution with a stirrer.

To check the completeness of separation of copper electrodes immersed 5 mm below the original position and continue the electrolysis. In the absence of plaque copper on svezheokrashennoj portion of the cathode electrolysis is considered ended.

Then, without turning off the current, washed with water and then turning off the current, washed with ethanol (10 cmof alcohol per one definition).

Cathode copper from the separated dried at 100−105 °C for 5 min, cooled in a desiccator and weighed using weights, which weighed a cathode and a charge of copper.

The electrolyte and rinse water poured into a measuring flask with a capacity of 200−250 cm, made up to the mark with water and mix. Retain electrolyte for the determination of Nickel.

The copper remaining in the electrolyte after the electrolysis, is determined in the form coloured compounds with cuprizone or lead diethyldithiocarbamate photometric method as described in the claims.3.2, 3.3.

(Changed edition, Rev. N 4).

3.2. The photometric method for the determination of copper in the electrolyte cuprizone

3.2.1. Pipette take 50 cmof the electrolyte solution and placed in a volumetric flask with a capacity of 100 cm; add 10 cmof ammonium citrate solution, 2 drops of solution of phenolphthalein and ammonia solution, diluted 1:4, to obtain a slightly pink color. Then add 1 cmof ammonia solution diluted 1:4, 10 cmcuprizone, made up to the mark with water and mix.

The pH of the solution should be of 8.5−9.0. the pH of the test solution on the indicator paper.

Optical density of the solution is measured after 5−30 min at a wavelength of 600 nm in a cuvette with a layer thickness of 30 mm. with a Solution of comparison in the measurement of optical density is water. At the same time carried out two test experience with all the applied reagents. The average value of optical density in the reference experiment is subtracted from the value of the optical density of the analyzed solution.

Mass of copper in the solution set of the calibration schedule, constructed as described in section 3.2.2.

3.2.2. Construction of calibration curve

Select 0; 2,0; 4,0; 6,0; 8,0 and 10,0 cmof solution B in a volumetric flask with a capacity of 100 cm, which corresponds to 0; 20; 40; 60; 80 and 100 micrograms of copper. Add 4 cmof the mixture of acids, 50 cmwater, 10 cmof ammonium citrate solution, 2 drops of phenolphthalein solution, ammonia solution, diluted 1:4 until a slightly pink color and 1 cmexcess, 10 cmcuprizone solution, made up to the mark with water and mix. The pH of the solution should be of 8.5−9.0.

Measurement of optical density produced as specified in claim 3.2.1.

On the found values of optical density and relative contents of copper to build the calibration graph.

3.3. The photometric method for the determination of copper and diethyldithiocarbamate lead in the electrolyte

3.3.1. Select aliquot part of 5−10 cmand placed in a beaker with a capacity of 50 cm, pour 5 cmof sulphuric acid, diluted (1:10), and evaporated to release vapors of sulfuric acid.

The solution was cooled, poured 10−20 cmof water was placed in a separating funnel with a capacity of 100 cmand dilute with water to volume of 50 cm. Add 10 cmof a solution of lead diethyldithiocarbamate and extracted within 2 min. After separation of layers, extract decanted into a volumetric flask with a capacity of 25 cm(where previously placed 1 g of anhydrous sodium sulfate).

The extraction was repeated with 10 cmof the extractant. The organic layer is decanted into the same volumetric flask, dilute to the mark with chloroform and mix.

Optical density of the solution is measured at a wavelength of 413 nm in a cuvette with an optimum thickness of the layer. Solution comparison in the measurement of optical density is carbon tetrachloride.

At the same time carried out two test experience. This is placed in a separatory funnel 4 cmof the mixture to dissolve, top up to 50 cmof water and then do as above. The average value of optical density in the reference experiment is subtracted from the value of the optical density of the analyzed solution.

Mass of copper set on a calibration schedule, constructed as described in section 3.3.2.

3.3.2. Construction of calibration curve

Six separatory funnels with a capacity of 100 cmis placed 0; 0,5; 1,0; 2,0; 3,0 and 5,0 cmstandard solution B. Pour water to a volume of 50 cmand further analysis is carried out according to claim 3.3.1.

Extraction and measurement of the optical density of the solution produced as described in paragraph 3.3.1.

On the found values of optical density and the respective contents of copper to build the calibration graph.

3.3−3.3.2. (Changed edition, Rev. N 4).

3.4. Atomic absorption method for the determination of copper in the electrolyte

3.4.1. Part of the electrolyte solution is placed in a beaker with a capacity of 100 cm, previously it was washed with this solution. The solution is sprayed into the flame and measure the absorbance in the flame at a wavelength of 324,7 nm.

Mass of copper in the solution set of the calibration schedule, constructed as described in section 3.4.2.

3.4.2. Construction of calibration curve

In a volumetric flask with a capacity of 100 cmselect 0; 5,0; 10,0; 15,0 and 20.0 cmof a solution, made up to the mark with water and mix. Solutions contain 0; 0,5; 1,0; 1,5 and 2,0 µg/cmof copper. The solutions were sprayed into the flame and measure the absorbance in the flame at a wavelength of 324,7 nm.

On the found values of optical density and the corresponding copper content build the calibration graph.

4. PROCESSING OF THE RESULTS

4.1. Mass fraction of copper in percent when using electrolytic and photometric methods for the determination of copper is calculated by the formula

.

Mass fraction of copper in percent when using electrolytic and atomic absorption methods for the determination of copper is calculated by the formula

,

where is the mass of the copper sample, g;

 — the mass of cathode, g;

 — the mass of the cathode with the deposited copper, g;

 — the mass of copper was found in the calibration schedule, mcg;

 — the mass of copper was found in the calibration schedule, µg/cm;

 — analyze the volume of the electrolyte, cm;

 — volume aliquote part of the electrolyte, cm.

4.2. The difference between the largest and smallest results of the three parallel determinations should not exceed 0,06%; between results of the two tests is 0.14%.

(Changed edition, Rev. N 4).

4.3. Determination of copper (at a mass proportion of her above 99.9%)

4.3.1. Mass fraction of copper in percent calculated by difference between 100 and the sum of all of certain impurities by the formula shown below

,

where , , is the average mass fraction of copper in certain impurities, %.

(Changed edition, Rev. N 2).

4.3.2. Discrepancies between the results of two parallel measurements of impurities in copper must not exceed the permissible differences given in the relevant standards for the determination of a particular impurity.

(Added, Rev. N 4).

APP. (Deleted, Rev. N 4).