GOST 27981.6-88

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  ГОСТ 27981.6-88

GOST 27981.6−88 Copper of high purity. Polarographic methods of analysis

GOST 27981.6−88

Group B59

STATE STANDARD OF THE USSR

HIGH PURITY COPPER

Polarographic methods of analysis

Copper of high purity. Methods of polarographic analysis

AXTU 1709

Valid from 01.01.1990
until 01.01.2000*
________________________________
* Expiration removed
Protocol N 7−95 Interstate Council
for standardization, Metrology and certification
(IUS N 11, 1995). — Note the manufacturer’s database.

INFORMATION DATA

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

PERFORMERS:

B. M. Rogov, E. N. Gazalov, I. Swan, V. P. Krasnonosov, L. N. Vasilyeva, N. And. Molostvov, V. I. Zyuzin, Z. P. Dutova, A. K. Opeskin

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 22.12.88 N 4443

3. The term of the first check — 1994

The frequency of inspection — 5 years

4. INTRODUCED FOR THE FIRST TIME

5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

This standard specifies the polarographic methods for determination of cadmium (for the mass concentration of 0.00005 and 0.0015%), antimony (at a mass fraction of 0.00006 to from 0,0015%) and tellurium (if the mass fraction of from 0.00003 to 0.0001%) in high purity copper.

1. GENERAL REQUIREMENTS

General requirements for method of analysis and safety requirements when performing analyses according to GOST 27981.0.

2. METHOD FOR THE DETERMINATION OF CADMIUM

The method is based on polarography solution containing cadmium at the background of 0.4 M hydrochloric acid and 0.12 M ammonium chloride. Potential peak towards the bottom of the mercury negative 0.8 V. Previously, the cadmium is separated from the copper by cementation on metallic aluminum.

2.1. Equipment, reagents, solutions

Polarograph type PPT-1 or PU-1.

Scales laboratory analytical type VLR (or other type) of the 2nd class of accuracy.

The glasses In the-1−250 TCS according to GOST 25336.

Flasks conical KN-1−250−14/23 TC GOST 25336.

Craters In the laboratory-36−80 TC GOST 25336.

Volumetric flasks 2−25−2, 2−100−2, 2−200−2, 2−1000−2 according GOST 1770.

Pipette 5−2-1, 6−2-5, 6−2-10, 2−2-20 according to GOST 20292*.
________________
* On the territory of the Russian Federation there are 29169−91 GOST, GOST 29227−91−29229−91 GOST, GOST 29251−91-GOST 29253−91, here and hereafter. — Note the manufacturer’s database.

Cylinders 1−5, 1−10, 1−25, 1−50 according to GOST 1770.

The filter paper (yellow ribbon).

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

Hydrochloric acid according to GOST 3118, diluted 1:1, and a solution of 0.05 mol/DM.

Aluminium granulated high purity.

Ammonium chloride according to GOST 3773.

Nitrogen gas according to GOST 9293.

Formalin according to GOST 1625*.
______________
* On the territory of the Russian Federation GOST 1625−89. — Note the manufacturer’s database.

Cadmium GOST 1467*.
______________
* On the territory of the Russian Federation GOST 1467−93. — Note the manufacturer’s database.

2.2. Preparation for assay

2.2.1. Preparation of standard solutions

Solution a: the weight of cadmium weight 0,100 g was dissolved with heating in 15 cmof nitric acid, diluted 1:1. The solution was evaporated to a volume of 2−3 cm, pour 10 cmof hydrochloric acid and evaporated to moist salts. Evaporation with 5 cmof hydrochloric acid is repeated twice. Then to the residue poured 5cmof hydrochloric acid and 50 cmof water, dissolved salts when heated. Cooled, put the solution in a volumetric flask with a capacity of 100 cmand adjusted to the mark with water.

1 cmof the solution contains 1 mg of cadmium.

Solution B: take 10 cmof solution A was placed in a volumetric flask with a capacity of 1000 cmand was adjusted to the mark with water.

1 cmof a solution contains 0.01 mg of cadmium.

Solution: take 10 cmof a solution and placed in a volumetric flask with a capacity of 200 cm, adjusted to the mark with water; use freshly prepared solution.

1 cmof the solution contains 0.0005 mg

cadmium.

2.3. Analysis

2.3.1. A sample of copper weighing 1,000 grams is placed in a conical flask with a capacity of 250 cm, flow 20 cmof nitric acid, diluted 1:1 and dissolved at room temperature. It is then heated and the solution is evaporated to wet salts. The residue is treated with 10 cmof hydrochloric acid and evaporated to dryness. For complete removal of nitration the residue is treated three times: once in 2−3 cmof formalin and twice with 10 cmof hydrochloric acid.

To the residue poured 100 cmwith molar concentration of 0.05 mol/DMof hydrochloric acid, add 1.5 g of ammonium chloride and dissolve salt. The solution was added 6−8 pellets of aluminum metal (weighing 3.5 to 4.0 g) and for (60±5) minutes is performed cementation of copper with occasional stirring.

The solution with the precipitated pellet copper, filtered through a filter paper, placing the filtrate in a beaker with a capacity of 250 cm.

The walls of the flask is washed 2−3 times heated to boiling water 5−6 times and the same water filter, attach the washings to the main filtrate.

The combined filtrate is evaporated to a volume of 10 cm, placed in a volumetric flask with a capacity of 25 cmand was adjusted to the mark with water.

From the solution and remove oxygen by blowing nitrogen for 10−15 minutes and spend polarography in the range of potentials from minus 0.5 to minus 0.9 In towards the bottom RT

Ooty.

2.3.2. Determine the conversion factor by a method of additives. For this 1 cmstandard solution is placed in a flask with a weighed copper and then continue the analysis as described in section 2.3.1.

The conversion factor is calculated by the formula

,

where the total height of the peak corresponding to the sum of the heights of peaks polarogram of cadmium in the sample solution and additives of cadmium in this solution, mm;

the peak height of cadmium in the sample solution, mm;

 — mass concentration of cadmium, introduced into the sample solution in the form of supplements, mg/cm.

2.4. Processing of the results

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

,

where the capacity of volumetric flasks, cm;

 — the conversion factor;

 — the weight of the portion of copper, g;

the peak height of cadmium in solution of the sample, mm.

2.4.2. Allowable absolute differences of the results of two parallel measurements at a confidence level =0.95 is (the rate of convergence) and the results of the analysis of the same samples obtained in two laboratories and one reference laboratory, but under different conditions (a measure of reproducibility) shall not exceed the values given in table.1.

Table 1

2.4.3. Control of the correctness of the results of the analysis carried out using standard samples of composition of copper.

The results of the analysis of samples recognized correctly if played mass fraction of component in the standard sample differs from the certified characteristics are not more than the value of 0.71, which is given in table.1.

2.4.4. Allowed to control the correctness of the results of the analysis carried out by the method of additions. The mass of the additive (the volume of a standard solution) is chosen so that the analytical signal of the designated component is increased 2−3 times compared to the analytical signal in the absence of additives.

The tests are considered valid if the found value differs from the additive introduced its value of not more than 0.71, where and  — the permissible discrepancy of the two results of the analysis for the sample and the sample with the additive.

3. METHOD FOR THE DETERMINATION OF ANTIMONY

The method is based on the electrochemical recovery of antimony ions in the background of 6 M hydrochloric acid containing 0.19 M sodium phosphonoacetate.

The peak potential of antimony in relation to the bottom of the mercury minus 0.15 V.

The separation of antimony from interfering impurities is carried out by its coprecipitation on iron hydroxide.

3.1. Equipment, reagents, solutions

Polarograph type PU-1 (variable current mode) or of the same type.

Gas analyzers of the 2nd class of accuracy of any type.

Desiccator, according to GOST 25336.

The glasses In the-1−250 TC GOST 25336 or N-1−250 TCS according to GOST 25336.

Volumetric flasks 2−25−2, 2−50−2, 2−100−2, 2−200−2, 2−1000−2, 1−1000−2, 1−200−2 according to GOST 1770.

Cylinders 1−10, 3−25, 3−250 according GOST 1770.

Pipette 4−2-1, 4−2-2, 5−2-5 according to GOST 20292.

Filter paper, medium density (yellow ribbon) with filtrowanie ground.

Porcelain Cup according to GOST 9147.

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

Sulfuric acid according to GOST 4204, diluted 1:1 and 1:5.

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

Ammonia water according to GOST 3760, diluted 1:1, 2% solution.

Alum salesonline a solution of 43 g/DM: 8.6 g gentoomaniac alum dissolved in 150 cmof water containing 20 cmof sulphuric acid, placed in a volumetric flask with a capacity of 200 cmand was adjusted to the mark with water.

1 cmof solution contains 5 mg of iron.

Hydrazine sulfate according to GOST 5841, perekristallizatsii; solution 50 g/DM: 70 g of hydrazine pour 200cmof water, heated to boiling and stirred to dissolve the salt. The solution is evaporated, without boiling, until the formation of crystalline film. Cooled at room temperature, the solution over the crystals drained, and the resulting salt is dried in a porcelain Cup in the desiccator.

Nitrogen gas according to GOST 9293.

Ammonium chloride according to GOST 3773, solution 20 g/DM.

Sodium posterolaterally (hipofosfit sodium) according to GOST 200.

Antimony GOST 108

9.

3.2. Preparation for assay

Preparation of standard solutions

Solution a: a sample of antimony concreteras weight 0,100 g placed in the beaker (or flask) with a capacity of 200−300 cm, flow 20 cmof sulfuric acid and dissolved with strong heating. Then cool, add 150−200 cmof water, stirred and again cooled. Poured 80 cmof sulphuric acid, cool and place the solution in a measuring flask with volume capacity of 1000 cmand was adjusted to the mark with water.

1 cmof solution A contains 0.1 mg of antimony.

Solution B: pipetted 5 cmof solution A was placed in a volumetric flask with a capacity of 50 cm, flow 10 cmof sulphuric acid diluted 1:1, and adjusted to the mark with water.

1 cmof a solution contains 0.01 mg of antimony.

Solution: pipetted 1 cmof solution A was placed in a volumetric flask with a capacity of 100 cm, flow 10 cmof sulphuric acid diluted 1:1, adjusted to the mark with water: the solution is prepared the day of analysis.

1 cmof the solution contains 0.001 mg

antimony.

3.3. Analysis

3.3.1. On the glasses, which will carry out the analysis of copper, applied with steklografom labels corresponding to 50, 100 and 150 cm.

3.3.2. A sample of copper with a mass of 2,000 g were placed in a glass with a capacity of 250 cm, flow 20 cmof nitric acid, diluted 1:1, and leave you without heat until the cessation of the violent reaction of the allocation of nitrogen oxides. Then solution is heated and evaporated up to wet salts. To the residue poured 30 cmof hydrochloric acid, water to a volume of 100 cmand heated to dissolve the salts. Bring to a boil, remove from heat and immediately injected under stirring 13−15 cmof a solution of hydrazine, left without heat for 10−15 minutes, while 2−3 times to mix.

To the obtained solution poured water to a volume of 100 cm, is introduced 1 cmof solution gentoomaniac alum and precipitated antimony on the iron hydroxide with ammonia diluted 1:1, until a stable blue coloration of the solution and add 5 cm.

Provide sediment to koagulirovat for 20−25 min and then filtered on a filter of «yellow ribbon» in the cone which is enclosed a little filtrowanie mass. The filter cake and a glass washed 5−6 times heated to boiling water containing 2% ammonium chloride and 2% ammonia.

The precipitate is then dissolved on the filter with 20 cmof hot hydrochloric acid, diluted 1:1, washed 3−4 times with hot water, collecting the filtrate in a beaker, which was carried out the precipitation of iron hydroxide. The total volume of the solution should be 50 cm.

The resulting solution was heated to boiling, removed from the plate and immediately injected with stirring 2 cmof a solution of hydrazine, allowed to stand for 10−15 min. Then pour water to a volume of 100 cm, injected 0.2 cmgentoomaniac alum, mix and repeat the precipitation of the hydroxides with ammonia diluted 1:1. Then filtered, the precipitate washed as described above.

The precipitate is dissolved on the filter in 20 cmhot sulphuric acid, diluted 1:5, the filter was washed 2−3 times with hot water, collecting the filtrate in a beaker, which conducted the deposition. Pour 5 cmof sulphuric acid diluted 1:1, and the solution evaporated until the appearance of white vapors, add 5−6 drops of nitric acid and again evaporate to white fumes. Again cool, and wash off the side of the Cup with water and evaporated until the appearance of white vapors, the operation is repeated.

The solution was evaporated to wet salts, poured 20 cmof hydrochloric acid diluted 1:1 add 0.4−0.5 g of sodium hypophosphite, solution boil for 1−2 min, cooled, placed in a volumetric flask with a capacity of 25 cmand was adjusted to the mark with hydrochloric acid diluted 1:1.

From the solution and remove oxygen by blowing nitrogen for 5−10 min, and polarography in the range of potentials from minus 0.08 to minus 0.20 In in relation to to

constant mercury.

3.3.3. Determine the conversion factor by a method of additives. For this aliquot part of the standard solution or B was placed in a glass sample of copper and then do as described in claim 3.3.2

,

where is the height of the peak corresponding to the sum of the heights of peaks polarogram of antimony in the analyzed sample solution and additives of antimony in the solution, mm;

 — the height of the peak of polarogram of antimony, obtained for the sample solution, mm;

 — mass concentration of antimony introduced into the sample solution in the form of supplements, mg/DM.

3.4. Processing of the results

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

,

where the capacity of volumetric flasks, cm;

 — the conversion factor;

 — weight of copper,

3.4.2. Allowable absolute discrepancies in the results of two parallel determinations for sample analysis at a confidence level =0.95 is (the rate of convergence) and the results of the analysis of the same samples obtained in two laboratories and one reference laboratory, but under different conditions (a measure of reproducibility) shall not exceed the values given in table.2.

Table 2

3.4.3. Control of the correctness of the results of the analysis carried out in accordance with PP.2.4.3, 2.4.4.

4. METHODS FOR DETERMINATION OF TELLURIUM

4.1.On the background of potassium iodide

The method is based on polarography solution containing tellurium, in the background itestosterone acid in the range of potentials from minus to minus 0,38 0,60 V.

4.1.1. Equipment, reagents, solutions

Polarograph type PPT-1 or PU-1.

Laboratory scales analytical any type of 2nd class of accuracy.

The glasses In the-1−250 TC GOST 25336.

Volumetric flasks 2−50−2, 2−100−2, 2−500−2 according GOST 1770.

Pipette 2−2-5, 2−2-10, 5−2-2 according to GOST 20292.

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

Hydrochloric acid according to GOST 3118.

Sulfuric acid according to GOST 4204, diluted 1:3.

A mixture of nitric and hydrochloric acids in a ratio of 1:3 (freshly made).

Potassium iodide according to GOST 4232, a solution of 2 mol/DM.

Ammonia water according to GOST 3760, a solution of 5:95.

Iron (III) sulfate 9-water according to GOST 9485, a solution of 1 g/DM.

Nitrogen gas according to GOST 9293.

Argon according to GOST 10157.

Tellurium of high purity according to normative-technical documentation.

4.1.2. Preparation for assay

4.1.2.1. Preparation of standard solutions

Solution a: a sample of tellurium by weight 0,100 g dissolved in 5 cmof nitric acid, diluted 1:1, evaporated the solution to dryness, not proKLIMA. To the residue poured 20 cmof hydrochloric acid, put the solution in a volumetric flask with a capacity of 100 cmand adjusted to the mark with water.

1 cmof the solution contains 1 mg of tellurium.

Solution B: take away 5 cmof solution A was placed in a volumetric flask with a capacity of 500 cm, poured 5cmof hydrochloric acid and was adjusted to the mark with water.

1 cmof a solution contains 0.01 mg of tellurium.

Solution: take 10 cmof solution B was placed in a volumetric flask with a capacity of 100 cmand adjusted to the mark with water.

1 cmof the solution contains 0.001 mg bodies

Lura.

4.1.2.2. Preparation of solutions comparison

For the preparation of solutions of comparison in a series of glasses with a capacity of 50 cmis placed 0,0; 2,0; 5,0; 10 cmstandard solution, add 0.2 cmof sulphuric acid and evaporated until the appearance of dense white fumes of sulfuric acid. Evaporation with 0.2 cmof sulphuric acid is carried out three times. Cool, pour 6 cmof a solution of potassium iodide and 20−30 cmof water, stirred, placed in a volumetric flask with a capacity of 50 cmand was adjusted to the mark with water. Solutions are stable for 4−6 hours

.

4.1.3. Analysis

A sample of copper weighing 1,000 grams is placed in a beaker with a capacity of 100 cm, 10−15 cm pournitric acid, diluted 1:1, and heated to dissolve sample. Cool, add 2 cmof iron sulfate solution, dilute with water to volume of 50 cm, is neutralized with ammonia prior to the deposition of iron hydroxide and 5 cmin excess. Heat the solution for 5−7 min, then filtered through a filter of medium density. Washed the filter with sediment 3−5 times with ammonia, diluted 5:95, and then 3−4 times with hot water.

Wash water residue from the filter into the glass, which conducted the deposition, poured 5cmof hydrochloric acid and heated until dissolved. In the solution re-precipitated ferric hydroxide with ammonia and filtered the precipitate on the same filter. The filter was washed 5−6 times with hot water. Dissolve the precipitate on the filter in the 10−15 cmof the mixture of acids and washed the filter 5−6 times with hot water.

The filtrate is evaporated to a volume of 10−15 cm, add 0.2 cmof sulphuric acid and evaporated until the appearance of dense white fumes. Evaporation with 0.2 cmof sulphuric acid is carried out three times. After cooling, pour 6 cmof a solution of potassium iodide, and 10−20 cmof water, stirred, placed in a volumetric flask with a capacity of 50 cmand was adjusted to the mark with water.

The solution was transferred into the electrolytic cell, is freed from oxygen by blowing nitrogen or argon. Polarography in the range of potentials from minus to minus 0,60 0,38 To coincide with the solutions of the comparison and control solution

experience.

4.1.4. Processing of the results

4.1.4.1. Mass fraction of tellurium () in percent is calculated by the formula

,

where is the height of the peak of the analyzed solution given in the reference experiment, mm.

 — capacity volumetric flasks, cm;

the average value of the ratio of wave heights obtained by polarography solutions of tellurium in comparison to the concentrations of these solutions, mm·cm/mg (see p.3.3.3.).

4.1.4.2. Allowable absolute discrepancies in the results of two parallel determinations for sample analysis at a confidence level =0.95 is (the rate of convergence) and the results of the analysis of the same sample obtained in different laboratories, and in the same laboratory but under different conditions (a measure of reproducibility) shall not exceed the values given in table.3.

Table 3

4.1.4.3. Control of the correctness of the results of the analysis carried out in accordance with PP.2.4.3, 2.4.4.

4.2. On the background of phosphoric acid

The method is based on polarography solution containing tellurium, in the background of phosphoric acid in the range of potentials from minus 0.6 to minus 1.5 In after preliminary isolation of tellurium on the iron hydroxide.

4.2.1. Equipment, reagents, solutions

Polarograph type PPT-1 or PU-1 (variable current mode).

Glass N-1−100 TC GOST 25336.

Volumetric flasks 1−50−2, 2−100−2, 2−500−2 according GOST 1770.

Pipette 3−2-5, 3−2-10 according to GOST 20292.

Cylinder 1−10, 3−25 GOST 1770.

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

Sulfuric acid according to GOST 4204, diluted 1:3.

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

Orthophosphoric acid according to GOST 6552, diluted 1:3.

Ammonia water according to GOST 3760 and a solution of 5:95.

Iron (III) sulfate 9-water according to GOST 9485, a solution of 1 g/DM.

Nitrogen according to GOST 9293.

Argon according to GOST 10157.

Tellurium of high purity according to normative-technical documentation.

4.2.2. Preparation for assay

4.2.2.1. Preparation of standard solutions

Solution a: a sample of tellurium by weight 0,100 g dissolved in 5 cmof nitric acid, diluted 1:1, evaporated the solution to dryness, not proKLIMA. To the residue poured 20 cmof hydrochloric acid, put the solution in a volumetric flask with a capacity of 100 cmand adjusted to the mark with water.

1 cmof the solution contains 1 mg of tellurium.

Solution B: 5 cmsolution And placed in a volumetric flask with a capacity of 500 cm, poured 5cmof hydrochloric acid, adjusted to the mark with water.

1 cmof a solution contains 0.01 mg of tellurium.

Solution: 10 cmof solution B is placed in a volumetric flask with a capacity of 100 cmand adjusted to the mark with water.

1 cmof the solution contains 0.001 mg bodies

Lura.

4.2.2.2. Preparation of solutions comparison

In a volumetric flask with a capacity of 50 cmis placed 1,0; 2,5; 5,0; 10,0 standard solution and 2,5; 5,0; 10,0 cmstandard solution B, which corresponds to 0,0010; 0,0025; 0,0050; 0,0100; 0,0250; 0,0500 and 0,1000 mg of tellurium. All flasks are poured in 25 cmof phosphoric acid diluted 1:3 and adjusted to the mark with water.

4.2.3. Analysis

A sample of copper with a mass of 0.50 to 5.0 g were placed in a glass with a capacity of 250 cm, 10−30 cm pournitric acid, diluted 1:1, and heated to dissolution. The solution is cooled and add 1−2 cmof iron sulfate solution, dilute with water to 50 cm, neutralized with ammonia prior to the deposition of iron hydroxide and poured an excess of ammonia 5 cm. Heat the solution for 5−7 min and then filtered. The precipitate is washed with ammonia, diluted 5:95, then dissolved on the filter in hot hydrochloric acid, diluted 1:1, collecting the solution in a glass, which conducted the deposition. Repeat the precipitation of iron hydroxide by ammonia, filtered, washed with hot ammonia, diluted 5:95.

The filter cake is dissolved in 20 cmof sulphuric acid, diluted 1:3, poured to the solution with a graduated cylinder of 10 cmof nitric acid and evaporated to dryness. The precipitate dissolved when heated in 5−25 cmof phosphoric acid diluted 1:3, transfer the solution into a measuring flask with a capacity of 10−50 cmand was adjusted to the mark with water.

The solution was transferred into the electrolytic cell, is freed from oxygen with nitrogen, argon or other inert gas. Then polarography in the range of potentials from minus 0.6 to 1.5 V relative to the bottom of the mercury (=-1,1).

Simultaneously carried polarographically solutions compared

niya.

4.2.4. Processing of the results

4.2.4 1. Mass fraction of tellurium () in percent is calculated by the formula

,

where the height of the peak of the test solution minus the height of the peak in the reference experiment, mm.

 — capacity volumetric flasks, cm;

the average value of the ratio of wave heights obtained by polarography solutions comparison of tellurium, to the mass concentrations of these solutions, mm·cm/mg (p.3.3.3);

 — weight of copper,

4.2.4.2. Allowable absolute discrepancies in the results of parallel measurements and analyses of the same samples are given in table.3.

4.2.4.3. Control of the correctness of the results of the analysis carried out in accordance with PP.2.4.3, 2.4.4.