GOST 13938.8-78

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  ГОСТ 13938.8-78

GOST 13938.8−78 Copper. Methods for determination of tin (with Amendments No. 1, 2, 3)

GOST 13938.8−78

Group B59

INTERSTATE STANDARD

COPPER

Methods for determination of tin

Copper. Methods for determination of tin

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 13938.8−68

4. The standard conforms to ISO 4751−84

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 (November 1999) with Amendments No. 1, 2, 3, approved in may 1982, June 1985, April 1988 (IUS 8−82, 8−85, 7−88)


This standard specifies the photometric and polarographic methods for determination of tin in copper grades according to GOST 859*, except M00k, M00b, and when the mass fraction of tin from 0.0005 to 0.08%.
______________
* On the territory of the Russian Federation GOST 859−2001. — Note the manufacturer’s database.

(Changed edition, Rev. N 3).

1. GENERAL REQUIREMENTS

General requirements for methods of analysis and safety requirements when performing tests according to GOST 13938.1.

Sec. 1. (Changed edition, Rev. N 3).

2. POLAROGRAPHIC METHOD (with mass fraction of tin from 0.0005 to 0.06%)

2.1. The essence of the method without deposition of tin with ferric hydroxide

The method is based on the polarographic determination of tin oxalate in the electrolyte containing methylene blue in the range of potentials from minus minus 0.65 to 1.0 V relative to the bottom of mercury. The tin in the form of oxalate complex responds to the mercury electrode, and the copper is precipitated in the form of low-soluble oxalate of copper and does not interfere with the determination of tin.

(Changed edition, Rev. N 1, 3).

2.2. Apparatus, reagents and solutions

Polarograph with the applied voltage.

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

Sulfuric acid according to GOST 4204, diluted 1:1 and 1:9.

Oxalic acid according to GOST 22180, 1 M solution.

Methylene blue (MG), a solution of 3.7 g/DM.

Mercury GOST 4658.

Nitrogen in the cylinder according to GOST 9293.

Tin GOST 860, brand 01.

Solutions of tin.

Solution A, prepared as follows: 0.1 g of finely powdered tin was dissolved in 10 cmof sulphuric acid, heated until complete dissolution of tin, cooled, poured 180 cmsulfuric acid, diluted 1:1, mix, transfer the solution into a flask with a capacity of 1 DM, the solution is topped up to the mark with water and mix.

1 cmof the solution contains 0.1 mg of tin.

Solution B is prepared as follows: 10 cmof the solution And transferred with a pipette into a measuring flask with a capacity of 100 cmand then filled to the mark with sulfuric acid diluted 1:9.

1 cmof the solution contains 0.01 mg of tin.

2.3. Analysis

2.3.1. A sample of copper with a mass of 0.50 g were placed in a glass with a capacity of 250 cm, and dissolved in 10 cmof nitric acid, diluted 1:1. Pour 10 cmof sulphuric acid diluted 1:1, is heated to release vapors of sulfuric acid, cooled, washed the walls of the beaker with sulfuric acid solution diluted 1:9, is heated again to release sulfuric acid vapors, cooled and washed the walls of the beaker with sulfuric acid, diluted 1:9. The solution was evaporated until the termination of allocation of steams of sulfuric acid (without drying), 25 cm pour thehot solution of oxalic acid. The solution was heated for 3−5 min and left for 20 min to precipitate the oxalate of copper. Then, the solution and the precipitate was transferred to a volumetric flask with a capacity of 50 cmwith a solution of oxalic acid. Add 1.5 cmof methylene blue solution, made up to the mark with a solution of oxalic acid and stirred. The solution with precipitate was placed in a dry glass and after settling, the precipitate of the solution was decanted into a vessel for the passage of nitrogen; the solution was purged with nitrogen for 15 min and transferred into the cell. Polarographic solution at the potentials from minus 0.65 to minus 1.0 V. the half-wave Potential of minus 0.9 In (bottom mercury).

The calculation is carried out by a method of additives. For this part of a solution of tin evaporated before the termination of allocation of steams of sulfuric acid without drying. The residue is dissolved in 10 or 20 cmof the analyzed solution, stirred, transferred into a vessel for passing nitrogen, purged with nitrogen for 15 min and polarographically as described above. The calculation results of the determination carried out as specified in clause 4.1.

(Changed edition, Rev. N 3).

2.4. The essence of the method of deposition of tin with ferric hydroxide

The method is based on the polarographic determination of tin oxalate in the electrolyte containing methylene blue in the range of potentials from minus 0.65 to minus 1 In the relative bottom of mercury. Tin and copper are separated by coprecipitation with ferric hydroxide (III).

2.5. Apparatus, reagents and solutions

Polarograph AC complete with all accessories.

Sulfuric acid according to GOST 4204, and a solution of 1:9.

Nitric acid according to GOST 4461.

Hydrochloric acid according to GOST 3118.

Oxalic acid according to GOST 22180, 1 M solution.

Ammonia water according to GOST 3760, solutions of 1:1 and 1:19.

Alum salesonline in the NTD, at 1.75% solution.

Methylene blue 0,37% solution.

Nitrogen in the cylinder according to GOST 9293.

Tin GOST 860, brand 01.

Solutions of tin.

Solution A, prepared as follows: 0.001 g of tin are dissolved in 10 cmof sulphuric acid when heated. The solution is placed in a measuring flask with volume capacity of 1000 cm, made up to the mark with sulfuric acid solution and stirred.

1 cmof solution A contains 0.1 mg of tin.

Solution B: 10 cmsolution And placed in a volumetric flask with a capacity of 100 cm, made up to the mark with sulfuric acid solution and stirred; prepared immediately before use.

1 cmof a solution contains 0.01 mg of tin.

Mercury GOST 4658.

2.6. Analysis

2.6.1. A sample of copper with a mass of 1.0 g was placed in a beaker with a capacity of 400 cmand dissolved in 15 cmof hydrochloric acid and 2 cmof nitric acid. When heated removes the oxides of nitrogen. To the solution add water to 200 cm, 2 cmgentoomaniac solution of alum and heated to a temperature of 60−70 °C. Then was added a solution of ammonia (1:1) to come off the precipitate of iron hydroxide and the transition of copper in an integrated ammiaka. After 1 h the solution was filtered through a filter of medium density and 5 times the precipitate was washed with ammonia solution (1:19). The filter cake is dissolved in 25 cmof a hot solution of oxalic acid, adding it in small portions. The solution is placed in a volumetric flask with a capacity of 50 cm. The filter is washed with a solution of oxalic acid. To the solution was added 1.5 cmof methylene blue solution, made up to the mark with a solution of oxalic acid and stirred. Part of this solution is placed in a vessel for polarographically and remove the air by nitrogen for 10−15 min polarographic Solution at the potentials from minus 0.65 to minus 1 In the relative bottom of mercury.

In parallel spend control experience. The average value of the heights of the peaks obtained in polarography solutions control experiments, subtracted from the height values of the peaks obtained in polarography the analyzed solution.

Mass of tin find for the calibration schedule.

2.6.2. To build a calibration curve in glasses with a capacity of 400 cmis placed 0,5; 1,0; 2,0; 4,0 and 6,0 cmof a solution with mass fraction of tin from 0.0005 to 0,006% or 0,5; 1,0; 2,0; 4,0 and 6,0 cmsolution And when the mass fraction of tin from 0.005 to 0.06%. To solutions add 200 cmof water, 2 cmof a solution of ammonium sulfate of iron and then do as described in claim 2.6.1.

According to the obtained values of the heights of the peaks and their corresponding grades of tin to build a calibration curve.

2.4−2.6. (Added, Rev. N 1).

3. PHOTOMETRIC METHOD (with mass fraction of tin of 0.0005 to 0.08%)

3.1. The essence of the method

The method is based on the formation of complex compounds of tin (IV) with phenylfluorone after the separation of tin from interfering elements by extraction with chloroform in the form of coppernet or coprecipitation with ferric hydroxide (III). Optical density of the solution is measured at a wavelength of 510 nm.

3.2. Apparatus, reagents and solutions

Sulfuric acid according to GOST 4204, and solutions of 1:1 and 1:50.

Nitric acid according to GOST 4461.

Hydrochloric acid according to GOST 3118 and a solution of 1:9.

The acid chloride.

Hydrogen peroxide according to GOST 10929.

Thiourea according to GOST 6344, 10% solution.

N-nitroso-N-phenylhydroxylamine ammonium salt according to NTD, 2% solution, freshly prepared.

Chloroform, distilled.

Tartaric acid according to GOST 5817, 50% solution.

Ascorbic acid, 10% solution, freshly prepared.

Ammonia water according to GOST 3760 and the solutions 1:1 and 1:50.

Bromine according to GOST 4109, saturated aqueous solution (bromine water).

Alum salesonline in the NTD, at 1.75% solution.

Gelatin GOST 11293, 0,5% solution, freshly prepared.

0.5 g of gelatin were placed in a glass with a capacity of 150 cm, add 20 cmof water and leave to swell. Then add 70 cmof water heated to a temperature of 70−80 °C, heated to boiling and cooled. The solution was made up to 100 cmwater, and stirred.

Ethyl alcohol 96%.

Phenylfluorone (2, 3, 7, trihydroxy-9-phenyl-6-fluoro), 0,03% alcohol solution containing 1 cmof sulfuric acid solution (1:1) to 100 cm.

Sodium chloride according to GOST 4233.

Tin GOST 860, brand 01.

Solutions of tin standard.

Solution A, prepared as follows: 0.001 g of tin are dissolved in 10 cmof sulphuric acid when heated. The solution is placed in a measuring flask with volume capacity of 1000 cm, made up to the mark with sulfuric acid solution 1:9 and stirred.

1 cmof solution A contains 0.1 mg of tin.

Solution B is prepared as follows: 10 cmof solution A is placed in a volumetric flask with a capacity of 100 cm, made up to the mark with sulfuric acid solution (1:9) and stirred; prepared immediately before use.

1 cmof a solution contains 0.01 mg of tin.

Indicator paper Congo.

3.3. Analysis

3.3.1. A sample of copper with a mass of 5.0 g is dissolved in 75 cmof hydrochloric acid in the presence of 1 g of sodium chloride. Gradually add 20 cmof hydrogen peroxide, preventing a violent reaction. The excess hydrogen peroxide is removed by boiling. The solution was then cooled, placed in a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix. The tin content in the resulting solution is determined as specified in paras.3.3.2 and 3.3.3 or 3.3.4.

3.3.2. 50 cmof solution with mass fraction of tin from 0.005 to 0,006% or 5 cmof solution with mass fraction of tin from 0.005 to 0.06% is placed in a separating funnel with a capacity of 250 cm. In the case of 5 cmof solution is poured a solution of hydrochloric acid to 50 cm. To the solution in separating funnel add 50 cmof a solution of thiourea and stirred. Then add 5 cmof a solution of N-nitroso-N-phenylhydroxylamine ammonium salt, stirred, and after 2 minutes extracted revocationof complex 10 cmof chloroform, shaking the contents for 2 min. the Organic layer was placed in separating funnel with a capacity of 100 cm. The extraction is carried out twice. The combined extracts are washed with twice 5 cmsulphuric acid 1:9. The extract was placed in a beaker with a capacity of 100 cm, add 5 cmof sulfuric acid solution (1:1), 5 cmof nitric acid solution, 2 cmof perchloric acid and the solution is evaporated on a sand bath to a volume of 1 cm.

After cooling, add 2 cmwater 1.0 cmgentoomaniac solution of alum and 0.3 cmof a solution of tartaric acid. The solution is neutralized with ammonia solution of 1:1 on the indicator paper Congo and placed in a volumetric flask with a capacity of 25 cm. To the solution was added 1.6 cmof sulfuric acid solution (1:1) and bromine water until the yellow color.

After 5 min added dropwise a solution of ascorbic acid to the bleaching solution and in excess of 1 cm. After 5 min, add 2.5 cmof a solution of gelatin, 5.0 cmphenylfluorone solution and add the solution to the mark with water. After addition of each reagent the solution was stirred. After 30 min, measure the optical density of the solution at a wavelength of 510 nm.

Solution comparison is the solution of the reference experiment.

Mass of tin find on a calibration schedule, constructed as described in section 3.3.4.

3.3.3. For separation of the tin by the coprecipitation with ferric hydroxide is placed 50 cmof the solution obtained in section 3.3.1, when the mass fraction of tin from 0,006% or 5 cmof solution with mass fraction of tin above 0,006% in a glass with a capacity of 400 cmand add water to 200 cm. To the solution are added 1 cmof solution gentoomaniac of alum and heated to a temperature of 60−70 °C. With constant stirring, add aqueous ammonia in such quantity that all the copper went to the compound, and in excess of 5 cm. After 15 minutes the precipitate is filtered on a filter of medium density. Walls of glass, double-washed with hot ammonia solution (1:50).

The filter residue is washed 5−6 times with the same ammonia solution. The precipitate from the filter washed into the beaker in which it was carried out the precipitation of the hydroxide, add 10 cmsulphuric acid (1:1), 150 cmof water and periostat hydroxide. The precipitate was filtered on the same filter and washed 2 times with a hot solution of ammonia (1:50). The precipitate of hydroxide washed from the filter into the beaker in which reprecipitation was performed, the filter washed several times 20 cmof hot sulfuric acid solution (1:9), collecting the solution in the beaker with the sediment. To the solution add 5 cmof sulfuric acid solution (1:1), 5 cmof nitric acid, 2 cmof perchloric acid. The solutions were evaporated on a sand bath to a volume of 1 cm.

After cooling, add 2 cmof water and 0.3 cmof a solution of tartaric acid, neutralized with ammonia solution (1:1) on the indicator paper Congo and then do as described in claim 3.3.4.

3.3.4. To build a calibration curve in five out of six volumetric flasks with a capacity of 25 cmis placed 0,25; 0,5; 1,0; 2,0 and 3,0 cmof solution B. to all flasks add 1.0 cmof gentoomaniac solution of alum, 0.3 cmof a solution of tartaric acid, neutralized with ammonia solution (1:1) on the indicator paper Congo and then do as described in claim 3.3.2.

Solution comparison is the solution not containing the solution B.

According to the obtained values of optical densities and corresponding contents of the tin to build the calibration graph.

Sec. 3. (Changed edition, Rev. N 1).

4. PROCESSING OF THE RESULTS

4.1. Mass fraction of tin () percent when polarographic determination and calculation by the method of additions described by the formula

,

where  — height of tin obtained by polarography the test solution, mm;

 — the volume of the analyzed solution, cm;

 — the weight of the portion of copper, g;

the value of the ratio of the wave height is added of a solution of tin to concentration, mm/mg/DM.

The value of the find as follows: polarographic the analyzed solution of copper with the addition of a solution of tin, from the resulting height () subtract the height of the wave corresponding to the tin content in the analyzed solution of copper (), and divide by the concentration (mg/DM).

.

(Changed edition, Rev. N 1).

4.1.1. Mass fraction of tin () percent when polarographic determination with a construction of calibration curve (p.2.6.1) is calculated according to the formula

,

where  — weight of tin, was found in the calibration schedule g;

 — weight of copper,

(Added, Rev. N 1).

4.2. Mass fraction of tin (), in per cent by photometric determination is calculated by the formula

,

where  — volume of the analyzed solution, cm;

 — volume aliquote part of the solution, cm;

 — the mass of tin was found in the calibration schedule g;

 — weight of copper,

(Changed edition, Rev. N 1).

4.3. Discrepancies in the results of two parallel measurements and the two tests should not exceed the values given in the table.

(Changed edition, Rev. N 3).

4.4. The differences in the assessment of mass fraction of tin used photometric method.

(Added, Rev. N 3).