GOST 13938.7-78
GOST 13938.7−78 Copper. Methods for determination of lead (with Amendments No. 1, 2, 3, 4)
GOST 13938.7−78
Group B59
INTERSTATE STANDARD
COPPER
Methods for determination of lead
Copper. Methods for determination of lead
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
3. REPLACE GOST 13938.7−68
4. The standard corresponds to the international standard ISO 4749−84
5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced |
Section number, paragraph |
| GOST 859−78 |
The introductory section; 3.2 |
| GOST 3118−77 |
2.2; 3.2 |
| GOST 3760−79 |
2.2; 3.2 |
| GOST 3778−77 |
2.2; 3.2 |
| GOST 4236−77 |
2.2 |
| GOST 4461−77 |
2.2; 3.2 |
| GOST 5457−75 |
3.2 |
| GOST 9293−74 |
2.2 |
| GOST 9849−86 |
3.2 |
| GOST 13938.1−78 |
1 |
| GOST 20448−90 |
3.2 |
| GOST 22861−93 |
2.2; 3.2 |
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, 4, approved in may 1982, April 1983, June 1985, April 1988 (IUS 8−82, 7 to 83, 8−85, 7−88)
This standard specifies the polarographic and atomic absorption (at a mass fraction of from 0.0005 to 0.06%) methods for determination of lead in copper grades according to GOST 859*.
________________
* On the territory of the Russian Federation GOST 859−2001. Here and hereinafter. — Note the manufacturer’s database.
(Changed edition, Rev. N 4).
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 4).
2. POLAROGRAPHIC METHOD for the DETERMINATION of LEAD (with a mass fraction of lead from 0.0005 to 0.06%)
2.1. The essence of the method
The method is based on the polarographic determination of lead on a background of 0.5 M solution of perchloric acid in the range of potentials from minus minus 0.45 to 0.85 and In towards the bottom of the mercury.
Lead is separated from the main mass of copper deposition solution of ammonia together with iron hydroxide or lanthanum followed by dissolving the hydroxide in perchloric acid.
2.2. Apparatus, reagents and solutions
Polarograph with the applied voltage.
Nitrogen in the cylinder according to GOST 9293.
Ammonia water according to GOST 3760, diluted 1:49.
Nitric acid according to GOST 4461, diluted 1:1 and 1:3.
Hydrochloric acid according to GOST 3118, diluted 1:1 and 1:100.
Iron (III) nitrate, a 1.5% solution, a solution of 5 g/DM. 1 cm
of solution contains 2 mg of iron.
Oxide of lanthanum.
Lanthanum chloride, semivodny.
Lanthanum nitrate, shestibalny.
A solution of lanthanum; prepared as follows: 2.4 g of lanthanum oxide dissolved in 15 cmof hydrochloric acid diluted 1:1, or 5.4 g of lanthanum chloride, or 6.2 g of lanthanum nitrate is first dissolved in water and then add 10 cm
of hydrochloric acid diluted 1:1. Solution top up with water to 1 DM
and stirred.
1 cmof solution contains 2 mg of lanthanum.
Perchloric acid 0.5 M solution.
Lead of high purity according to GOST 22861 or lead according to GOST 3778*.
________________
* On the territory of the Russian Federation GOST 3778−98. Here and hereinafter. — Note the manufacturer’s database.
Lead nitrate according to GOST 4236.
Solutions of lead.
Solution A, prepared as follows: 0,500 g of lead dissolved in 25 cmof nitric acid, diluted 1:3, pour the 100 cm
of water, the solution was poured into a volumetric flask with a capacity of 1 DM
, made up to the mark with water and mix.
1 cmof solution contains 0.5 mg of lead.
Solution B is prepared as follows: pipette select 20 cmof solution A in a beaker with a capacity of 200 cm
, add 5 cm
of perchloric acid and evaporate the solution until the appearance of fumes of perchloric acid. The residue is cooled, add 10−15 cm
of water and evaporate the solution almost to stop the allocation of fumes of perchloric acid. After cooling, to the residue poured in 50 cm
0.5 M solution of perchloric acid and heat the solution under a watch glass to boil. The solution was cooled and poured into a volumetric flask with a capacity of 500 cm
, made up to the mark 0.5 m solution of perchloric acid and stirred.
1 cmof the solution contains 0.02 mg of lead.
Solution; prepared as follows: 0,160 g of lead nitrate or 0,100 g of lead dissolved in 20 cmof a solution of nitric acid. With the use of metallic lead for the removal of oxides of nitrogen the solution was heated and then cooled. The solution is transferred into a measuring flask with volume capacity of 1000 cm
, made up to the mark with water and mix.
1 cmof the solution contains 0.1 mg of lead.
Solution G; 50 cmof the solution In placed in a volumetric flask with a capacity of 500 cm
, add 5 cm
of nitric acid, made up to the mark with water and mix. Solution store no more than 5 hours.
1 cmsolution G contains 0.01 mg of lead.
Solutions of lead standard; prepared as follows: in a volumetric flask with a capacity of 100 cmwith microburette measure 0; 0,5; 1,5; 2,5; 4,0; 5,0; 7,5; 10,0 and 15.0 cm
of a solution, made up to the mark 0.5 m solution of perchloric acid and stirred. The solutions contain 0; 0,1; 0,3; 0,5; 0,8; 1,0; 1,5; 2,0 and 3.0 mg/DM
lead. The solutions were prepared immediately before polarographically.
Allowed the use of other reagents, subject to obtaining the metrological characteristics are not inferior to those specified in the standard.
(Changed edition, Rev. N 1, 2, 4).
2.3. Analysis
2.3.1. A sample of copper with a mass of 5.0 g is dissolved in 25 cmof nitrogen and 5 cm
of hydrochloric acid under the watch glass. The solution is heated to remove the oxides of nitrogen, then poured into a volumetric flask with a capacity of 100 cm
, made up to the mark with water and mix. In the analysis of copper 20 cm
solution (for the mass concentration of lead up to 0.003%) or 10 cm
(for the mass concentration of lead of more than 0,003%) were placed in a glass with a capacity of 300 cm
, is diluted with water to 150−200 cm
, add 2 cm
of a solution of iron or lanthanum for the mass concentration of lead up to 0.01% and 10 cm
of a solution of iron or lanthanum for the mass concentration of lead above 0.01%, heat the solution to 60 °C and precipitated hydroxide in ammonia solution.
After coagulation of the precipitate for 15 min, the precipitate was filtered on a medium density filter and washed several times with hot solution of ammonia, diluted 1:49. The precipitate of the hydroxide with the hot water wash away the glass in which was conducted the deposition, the filter is washed with 10 cmof hot hydrochloric acid diluted 1:1 and then three times with hot hydrochloric acid, diluted 1:100. Hydroxide re-precipitated with aqueous ammonia as described above.
The precipitate of hydroxide washed from the filter approximately 30 cm0.5 M solution of perchloric acid, heated to dissolve the solids, cooled, transfer the solution into a volumetric flask with a capacity of 50 cm
and topped with a 0.5 M solution of perchloric acid to a label (the starting solution).
In the analysis of copper with a mass fraction of lead from 0.0005 to 0.01% of the source solution is placed in a vessel for the passage of nitrogen. Miss nitrogen for 15 min, pour the solution into the cell and polarographic in the range of potentials from minus to minus 0,85 0,45 V.
In the analysis of copper with a mass fraction of lead above 0.01% in a volumetric flask with a capacity of 50 cmis placed 10 cm
initial solution, the solution is topped up to the mark 0.5 m solution of perchloric acid and stirred.
Part of the solution is placed in a vessel for transmission of nitrogen and then do as above.
At the same time carried out two test experience to account for the lead content of the used reagents.
(Changed edition, Rev. N 1, 2).
2.3.2. A sample of copper with a mass of 1.0 g was placed in a beaker with a capacity of 400 cm, and dissolved in 10 cm
of nitric acid solution. Beaker cover watch glass, and when heated removes the oxides of nitrogen.
To the solution poured water up to 150 cmand 10 cm
in a 1.5% solution of nitrate of iron (III) or 10 cm
of a solution of lanthanum. The solution is heated to a temperature of 60 °C and add such a quantity of water of ammonia to the copper passed into solution in the form of the ammonia complex.
After 15 minutes the precipitate is filtered off on a medium density filter and washed several times with hot solution of ammonia. The precipitate is washed with hot water into a glass, which conducted the deposition. The precipitate is dissolved in 5 cmof hydrochloric acid. Then the hydroxide is again precipitated with aqueous ammonia as described above. The precipitate was filtered off through the same filter and dissolved in 25 cm
of hot hydrochloric acid, adding it in small portions. The solution was cooled and placed in a volumetric flask with a capacity of 50 cm
, add solution of perchloric acid to the mark and mix. Part of the solution is placed in a vessel for polarographically and remove oxygen by passing nitrogen for 10−15 min. a Solution of polarography in the range of potentials from minus to minus 0,45 0,85 In (towards the bottom of the mercury).
Simultaneously conduct control experiments. The average height of the peaks obtained in polarography solutions control experiments, subtracted from the height of the peaks obtained in polarographically analyzed solutions.
The mass of lead corresponding to the difference of the peaks, find the calibration schedule, constructed as described in section
2.3.3. For constructing calibration graphs for the mass fraction of lead from 0.0005 to 0,006% in five of the six tumblers with a capacity of 400 cmis placed 0,5; 1,0; 2,0; 4,0 and 6,0 cm
solution G, while the mass fraction of lead from 0.005 to 0.06% in five of the six cups are placed 0,5; 1,0; 2,0; 4,0 and 6,0 cm
of solution B. To each beaker was added 10 cm
of nitric acid, in 150 cm
of water, 10 cm
of 1.5%cent solution of nitrate of iron, or 10 cm
of a solution of lanthanum and further receives, as described in Chapter
According to the obtained values of the heights of peaks and the relative content of lead build the calibration graph.
2.3.2,
3. ATOMIC ABSORPTION METHOD for the DETERMINATION of LEAD (with a mass fraction of lead from 0.0005 to 0.06%)
3.1. The method is based on dissolving the samples in nitric acid and measuring the absorption line of lead with the introduction of hydrochloric acid or nitric acid solutions in the flame acetylene-air at a wavelength is 283.3 nm.
3.2. Apparatus, reagents and solutions
Spectrophotometer, atomic absorption, comprising a lamp with a lead hollow cathode burner flame acetylene-air or propane-butane-air and spray system.
Acetylene according to GOST 5457.
Propane-butane according to GOST 20448.
Air compressor.
Nitric acid according to GOST 4461, diluted 1:1, and a solution of 0.1 mol/DM.
Copper electrolyte according to the GOST 859 and the copper solution of 100 g/l: 10.0 g of copper was placed in a conical flask with a capacity of 250 cm
, 70 cm pour
nitric acid, diluted 1:1, and heated to dissolution. The solution was transferred to volumetric flask with a capacity of 100 cm
, made up to the mark with water and mix.
1 cmcontains 0.1 g of copper.
Lead of high purity according to GOST 22861 or lead according to GOST 3778.
Solutions of lead standard.
Solution A, prepared as follows: 1.0 g of lead was placed in a conical flask with a capacity of 100 cmand dissolved in 10 cm
of nitric acid, diluted 1:1. The solution was transferred to volumetric flask with a capacity of 1 DM
, made up to the mark with water and mix.
1 cmof the solution contains 1 mg lead.
Solution B is prepared as follows: 50 cmsolution And placed in a measuring flask with volume capacity of 1000 cm
, made up to the mark with water and mix.
1 cmof the solution contains 0.005 mg of lead.
Hydrochloric acid according to GOST 3118 and a solution of 1:1.
Ammonia water according to GOST 3760 and a solution of 1:99.
Iron according to GOST 9849, nitric-acid solution of 25 g/DM.
Universal indicator paper.
3.1, 3.2. (Changed edition, Rev. N 4).
3.3. Analysis
3.3.1. In the determination of lead in excess of 0,005% of a sample of copper with a mass of 2.0 g was placed in a conical flask with a capacity of 100 cmand dissolved in 20−25 cm
of nitric acid, diluted 1:1. The solution was transferred to volumetric flask with a capacity of 100 cm
, made up to the mark with water and mix. The resulting copper solution sprayed into the flame of atomic absorption spectrophotometer and measure the absorbance in the flame when the wavelength is 283.3 nm.
At the same time conducting follow-up experience with all the applied reagents. The value of the optical density of the solution in the reference experiment is subtracted from the value of the optical density of the analyzed solution.
A lot of lead in the solution set for the calibration schedule.
Allowed to determine the mass fraction of lead to use the addition method.
(Changed edition, Rev. N 2, 4).
3.3.1 a. When the mass fraction of lead and 0.005% suspension of copper with a mass of 5.0 g is placed in a beaker with a capacity of 400 cmand dissolved in 25 cm
of nitric acid. Heated until the termination of allocation of oxides of nitrogen. Then pour 250 cm
water and 5 cm
of a solution of iron, heated to a temperature of 60 °C. Pour the ammonia in such quantity that the whole of the copper passed into the ammonia complex and 5 cm
. Heated solution at a temperature of 60−70 °C to coagulate the precipitate. Filtered through a medium density filter and washed 3−4 times with hot ammonia solution (1:99). Dissolve the precipitate on the filter with 10 cm
of hot hydrochloric acid (1:1), collecting the filtrate in a beaker, where they had a deposition. The filter is washed with hot water until neutral reaction of the filtrate (test by universal indicator paper). The solution after cooling was placed in a volumetric flask with a capacity of 25 or 50 cm
, is diluted to the mark with water and mix.
Measure the absorption lines of lead, spraying the solution into the flame of acetylene-air, when the wavelength is 283.3 nm simultaneously with the solution of the control experience and solutions to build the calibration curve.
Allowed in the sample solution the determination of bismuth (0,0003 to 0.005%), tin (0.01 to 0.06%) and antimony (from 0.0005 to 0.02%).
Mass of lead is determined by the calibration schedule.
(Added, Rev. N 4).
3.3.2. The construction of a graded graph when the mass fraction of lead from 0.001 to 0.1%
In a volumetric flask with a capacity of 100 cmis placed 0; 0,5; 1; 2; 4 and 6 cm
of solution B, which corresponds to 0, 50, 100, 200, 400 and 600 µg of lead, add 10 cm
of copper solution, made up to the mark with water and mix.
Measure the absorbance of the solutions prepared as described in section 3.3.
According to the obtained values of optical densities and corresponding content of lead build the calibration graph.
(Changed edition, Rev. N 4).
3.3.2. Construction of calibration curve for the mass concentration of lead from 0.0005 to 0.001%
To build a calibration curve of six tumblers with a capacity of 400 cmis placed in 5.0 g of copper was dissolved in accordance with clause 3.3.1; pour 200−250 cm
water and 5 cm
of nitric acid solution of iron. In five of the six cups, add 0; 0,5; 2,0; 5,0 and 10,0 cm
standard solution B, and further analysis is continued in accordance with paragraph 3.3.1 a. According to the obtained values of optical density and corresponding concentrations of standard solutions to build the calibration graph.
(Added, Rev. N 4).
4. PROCESSING OF THE RESULTS
4.1. Mass fraction of lead in the percentage polarographic determination calculated by the formula
where wave height in lead, obtained in polarography the analyzed solution, minus the height of the waves in the reference experiment, mm.
— weight of copper corresponding to aliquote part of the solution, taken for polarographically, g;
— the volume of the analyzed solution, cm
;
the value of the ratio of the wave height of lead standard solution by its concentration, mm/mg/DM
.
The value for the selected sensitivity of the instrument find, polarography two standard solution (similar concentration of lead and its concentration in the sample solution) in the same interval of potentials, and calculated by the formula
where 
where ,
— concentration of standard solutions, mg/DM
;
,
— height of waves, obtained by polarography standard solutions.
4.1.1. Mass fraction of lead in percent with polarographic detection construction of calibration curve is calculated by the formula
where is the mass of lead was found in the calibration schedule g;
— weight of copper,
(Added, Rev. N 1).
4.2. Mass fraction of lead in the percentage of atomic-absorption determination is calculated by the formula
where is the mass of lead was found in the calibration schedule, mcg;
— weight of copper,
4.3. Discrepancies in the results of two parallel measurements and the two tests should not exceed the values given in the table.
| Mass fraction of lead, % |
The absolute maximum discrepancy, %, results | |
| parallel definitions |
tests | |
| To from 0,0005 0,0010 incl. |
0,0002 |
0,0003 |
| SV. 0,0010 «0,0030 « |
0,0004 |
About 0.0006 |
| «0,0030» 0,0100 « |
0,0008 |
0,0010 |
| «0,010» 0,030 « |
0,002 |
0,004 |
| «0,030» to 0,060 « |
0,004 |
0,006 |
(Changed edition, Rev. N 4).
4.4. The differences in the assessment of mass fraction of lead used polarographic method.
(Added, Rev. N 4).
