GOST 12697.8-77
GOST 12697.8−77 Aluminum. Methods for determination of copper (with Amendments No. 1, 2)
GOST 12697.8−77
Group B59
INTERSTATE STANDARD
ALUMINIUM
Methods for determination of copper
Aluminium. Methods for determination of copper
ISS 77.120.10
AXTU 1709
Date of introduction 1979−01−01
The decision of the State standards Committee of the Council of Ministers of the USSR from
Limitation of actions taken by Protocol No. 3−93 Interstate Council for standardization, Metrology and certification (ICS 5−6-93)
REPLACE GOST 12704−67 in part of sec. 2, 3
EDITION with Amendments No. 1, 2 approved in November 1985, may 1988 (IUS 2−86, 8−88).
This standard specifies the photometric and polarographic methods for the determination of copper in aluminum.
(Changed edition, Rev. N 2).
1. GENERAL REQUIREMENTS
1.1. General requirements for methods of analysis GOST 12697.1−77 and GOST 25086−87.
(Changed edition, Rev. N 1, 2).
2. The PHOTOMETRIC METHOD for the DETERMINATION of COPPER (at a mass fraction of copper from of 0.0002 to 0.08%)
2.1. The essence of the method
The method is based on the formation of diethyldithiophosphate copper, which is extracted with carbon tetrachloride. Colored solution diethyldithiophosphate copper photometered in 
2.2. Apparatus, reagents and solutions
Types photoelectrocolorimeter FEK-56M, PEC-60, KLF or the types of spectrophotometer SF-16, SF-26 or similar type.
A laboratory autotransformer (Latr) type Latr-1M or selenium rectifier, applying the electrodes of the Fisher.
Laboratory scales according to GOST 24104−88* 2nd accuracy class with the weighing error of 0.0002 g.
__________________
* From 1 July 2002 was put into effect GOST 24104−2001** (here and below).
** On the territory of the Russian Federation GOST R 53228−2008, here and hereafter. — Note the manufacturer’s database.
Distilled water not containing heavy metals. The water is cleaned from traces of heavy metals passing through the layer of strongly acidic cation exchange resin (KU-1, KU-2) at a speed of 50 cm/min; 40−50 g of cation exchange resin, screened from dust, placed in a beaker with a capacity of 400 cm
, 80−100 cm poured
hydrochloric acid diluted 1:1, and heated for 30 min. the Acid is drained and the resin washed repeatedly with water while stirring by decantation till neutral reaction on methyl orange.
The cation resin is transferred into the column of ground with a faucet on the bottom of which laid a wad of glass wool. A column of cation exchange resin were filled with distilled water. The layer of the cation must always be covered with water. The absorption properties of the resin after saturation regenerate hydrochloric acid and water.
All reagents are prepared in purified in such way water.
Diethyldithiophosphate Nickel solution with a mass fraction of 0.04%.
Hydrochloric acid of high purity according to GOST 14261−77 diluted 1:1, the solutions of 4 mol/land 0.1 mol/DM
.
Nitric acid GOST 4461−77 diluted 1:1.
Hydrogen peroxide according to GOST 10929−76, a solution with a mass fraction of 3%.
Carbon tetrachloride according to GOST 20288−74.
Copper, electrolytic.
Solutions of copper standard.
Solution A, prepared as follows: 0.1 g of copper is dissolved in 5 cmof nitric acid. After dissolution, add 10 cm
of hydrochloric acid diluted 1:1, evaporated to a small volume. Evaporation with the same portions of hydrochloric acid repeated two more times.
To the residue add 15 cmof hydrochloric acid diluted 1:1, transfer the solution into a measuring flask with volume capacity of 1000 cm
, made up to the mark with water and mix.
1 cmof solution A contains 0.1 mg of copper (Cu).
Solution B is prepared before use as follows: pipetted 10 cmof solution A in a volumetric flask with a capacity of 500 cm
, made up to the mark with water and mix.
1 cmof a solution contains 0.002 mg of copper (Cu).
(Revised edition, Edit
. N 2).
2.3. Analysis
2.3.1. Weighed aluminium weighing 1 g is placed in a beaker with a capacity of 250 cm, 30 cm, poured
hydrochloric acid diluted 1:1, and covered with a glass watch glass. Upon completion of the reaction wash the glass and the side of the Cup with hot water and heated to dissolve sample. Then pour 1 cm
of a solution of hydrogen peroxide and evaporate the solution until a wet residue of salts.
Then pour 2 cmof hydrochloric acid diluted 1:1, 20−30 cm
of hot water and heated to dissolve the salts. After cooling, the solution was transferred to volumetric flask with a capacity of 100 cm
, is diluted to the mark with water and mix.
Pipetted 5−50 cmof solution, depending on the assumed mass fraction of copper in a separatory funnel with a capacity of 250 cm
. Diluted solution of 0.1 mol/DM
solution of hydrochloric acid to 100 cm
, add 3 cm
of a solution of diethyldithiophosphate Nickel and poured from the burette 5 cm
of carbon tetrachloride. The contents of the funnel vigorously shaken for 1 minute, after phase separation, merge the painted layer of carbon tetrachloride in a dry cylinder with a glass stopper with a capacity of 25 cm
.
In a separatory funnel pour another 5 cmof carbon tetrachloride and repeat the extraction. The extract is poured into the same cylinder. Carefully separate the organic phase from the water, avoiding contact with the aqueous phase in the cylinder. To remove residual moisture during the filling of the cuvette, the solution was passed through a dry ash-free filter.
Optical density of the solution is measured on a photoelectrocolorimeter or spectrophotometer, given that a maximum of light absorption of solutions corresponds to a wavelength of 420 nm.
Solution comparison is the solution of carbon tetrachloride.
At the same time spend control experience. This 30 cmof hydrochloric acid diluted 1:1, evaporated to a volume of 0.5 cm
, pour 2 cm
of hydrochloric acid diluted 1:1, 30 cm
of water, and heat. After cooling, the solution was transferred to volumetric flask with a capacity of 100 cm
, is diluted to the mark with water, and further analysis is carried out as described above.
Mass of copper is determined according to the calibration schedule, taking into account the amendment in the reference experiment.
2.3.2. A sample of high-purity aluminium, made in the form of two rods, cleaned by boiling in hydrochloric acid, diluted 1:1 for 10 min.
The rods are then washed with water, dried at a temperature of 105−110 °C and weigh after cooling.
In a quartz glass with a capacity of 100−200 cm30 cm pour
4 mol/DM
hydrochloric acid solution of high purity. The rods reinforce the holders of high-purity aluminium or titanium that are attached to the terminals Later. Then the rods are immersed in a glass of acid, include Latr in the network and dissolve the sample in the range of voltage of 10−20 V for 15 min during this time dissolve about 1 g of aluminum. Then Latr turned off, disconnect the rods, washed with water, dried and weighed. From the difference of the masses determine the amount of soluble aluminum. The solution was evaporated to obtain a wet residue salts, pour 2 cm
of hydrochloric acid diluted 1:1, 30 cm
of hot water and heated to dissolve the salts. Allowed the decomposition of the sample is performed by means of the selenium rectifier, applying the electrodes of the Fisher.
After cooling, the solution was transferred to separating funnel capacity of 250 cm, is diluted to 100 cm
with water, add 3 cm
of a solution of diethyldithiophosphate of Nickel and act as specified in claim
4 mol/DM
hydrochloric acid solution is evaporated to a volume of 0.5 cm
, pour 2 cm
of hydrochloric acid diluted 1:1, and further conduct an analysis as specified
above.
2.3.3. Construction of calibration curve
In a separating funnel with a capacity of 200 cmpoured from microburette 0; 1; 2; 4; 6; 8 cm
standard solution B, which corresponds to 0; 0,002, 0,004; 0,008; 0,012; 0,016 mg of copper.
To each separating funnel pour 100 cmof 0.1 mol/DM
hydrochloric acid solution, 3 cm
of diethyldithiophosphate Nickel, 5 cm
of carbon tetrachloride and then carry out the analysis as described in section
Solution comparison is the solution, in which copper was not added.
According to the obtained values of optical density of solutions and the known masses of copper to build the calibration graph.
2.3.1−2.3.3. (Changed edition, Rev. N 2).
2.4. Processing of the results
2.4.1. Mass fraction of copper () in percent is calculated by the formula
where is the mass of copper was found in the calibration graphics mg;
— the total volume of solution, cm
;
— volume aliquote part of the solution, cm
;
the weight of aluminium,
2.4.2. Permissible discrepancies in the results of parallel definitions should not exceed the values given in table.1.
Table 1
| Mass fraction of copper, % |
Allowable difference, % | |
| convergence Rel. |
reproducibility, Rel. | |
| From 0,0002 to 0,003 incl. |
30 |
45 |
| SV. Of 0.003 «to 0.01 « |
20 |
30 |
| «Is 0.01» to 0.03 « |
15 |
25 |
| «0,03» 0,08 « |
10 |
15 |
(Changed edition, Rev. N 2).
3. POLAROGRAPHIC METHOD for the DETERMINATION of COPPER (at a mass fraction of copper from 0.001 to 0.08%)
3.1. The essence of the method
The method is based on polarography of copper from an appropriately prepared solution in the voltage interval from minus 0.05 to minus 0.4 V.
3.2. Apparatus, reagents and solutions
Polarograph AC type PU-1 or similar type.
Laboratory scales according to GOST 24104−88 of the 2nd accuracy class with the weighing error of 0.0002 g.
The gaseous nitrogen according to GOST 9293−74.
Aluminum brand A995 according to GOST 11069−2001.
Solution of aluminum 28 g/DM; prepared as follows: 14 g of aluminum is placed in a beaker with a capacity of 800 cm
, dissolved in 300 cm
of hydrochloric acid diluted 1:1 and added to accelerate the dissolving 1−2 drops of metallic mercury. The solution was transferred to volumetric flask with a capacity of 500 cm
, is diluted to the mark with water and mix.
Bromine according to GOST 4109−79.
Hydroxylamine hydrochloric acid according to GOST 5456−79, a freshly prepared solution with a mass fraction of 10%.
Nitric acid GOST 4461−77 diluted 1:1.
Hydrochloric acid by the GOST 3118−77, diluted 1:1.
Mercury GOST 4658−73.
Copper, electrolytic.
Solutions of copper standard.
Solution A, prepared as follows: 0,1400 g of copper is dissolved in 10 cmof nitric acid, diluted 1:1, add 10 cm
of hydrochloric acid and evaporated to dryness. Evaporation again with 10 cm
of hydrochloric acid to obtain a wet residue of salts. The residue is dissolved in water, the solution was transferred into a measuring flask with volume capacity of 1000 cm
, made up to the mark with water and mix.
1 cmof solution A contains 0.14 mg of copper (Cu).
Solution B is prepared before use as follows: pipette take 50 cmof solution A in a volumetric flask with a capacity of 500 cm
, made up to the mark and mix.
1 cmof solution B contains 0,014 mg copper (Cu).
(Changed edition, Rev.
N 2).
3.3. Analysis
3.3.1. Weighed aluminium weighing 0.7 g was placed in a beaker with a capacity of 150 cmand dissolved in 20 cm
of hydrochloric acid diluted 1:1. Beaker cover watch glass, and heated to dissolve sample. Once dissolved, add 2−3 drops of bromine and evaporated the solution until a wet residue of salts. The solution was then cooled, washed the glass and the side of the Cup a small amount of water and evaporated again to obtain a wet residue of salts.
The residue is dissolved in 10−15 cmof hot water, add 2cm
of a solution of hydroxylamine hydrochloric acid and boil for 1−2 min. then solution was cooled, transferred to a volumetric flask with a capacity of 25 cm
, is diluted to the mark with water and mix.
Part of the solution is taken into the cell and Donna mercury, pass nitrogen for 5 min and polarographic copper in the voltage interval from minus 0.05 to minus 0.4 V At the required sensitivity of the device.
Lead and zinc are determined simultaneously from the same solution, polarography lead in the voltage interval from minus 0.35 to 0.8 V, and the zinc from minus 0.8 to minus 1.2 V.
At the same time spend control experience.
Mass of copper is determined according to the calibration schedule, taking into account the amendment in the reference experiment.
3.3.2. Construction of calibration curve (when the mass fraction of copper from 0.001 to 0.01%).
In a glass with a capacity of 150 cmis placed 25 cm
of a solution of aluminium corresponding to 0.7 g of aluminium, and from microburette add 0; 0,5; 1,0; 2,0; 3,0 and 5,0 cm
of solution B, which correspond to 0; 0,007; 0,014; 0,028; and 0,042 0,070 mg of copper.
In each glass add 2−3 drops of bromine and evaporated to obtain a wet residue of salts. The side of the Cup washed with water and again evaporated to moist residue of salts. Then the balance of salts dissolved by heating in 10−15 cmof water, pour 2 cm
of a solution of hydroxylamine and boil for 1−2 min. Then carry out the analysis as described in section
According to the data obtained polarographically solutions, and the known masses of copper to build the calibration graph.
When you replace the capillaries, you need to build a new schedule.
(Changed edition, Rev. N 2).
3.3.3. Construction of calibration curve (when the mass fraction of copper from 0.01 to 0.08%).
In a glass with a capacity of 150 cmis placed 25 cm
of a solution of aluminium corresponding to 0.7 g of aluminum, add and 0; 0,5; 1,0; 2,0; 3,0 and 5,0 cm
of solution A, which correspond to 0; 0,07; 0,14; 0,28; 0,42 and 0.70 mg of copper.
Further analysis is carried out as specified in clause
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 was found in the calibration graphics mg;
the weight of aluminium,
3.4.2. Permissible discrepancies in the results of parallel definitions should not exceed the values given in table.2.
Table 2
| Mass fraction of copper, % |
Allowable difference, % | |
| convergence Rel. |
reproducibility, Rel. | |
| From 0.001 to 0.003 incl. |
30 |
45 |
| SV. Of 0.003 «to 0.01 « |
20 |
30 |
| «Is 0.01» to 0.03 « |
15 |
25 |
| «0,03» 0,08 « |
10 |
15 |
(Changed edition, Rev. N 2).
