GOST 25284.6-95
GOST 25284.6−95 Alloy zinc. Methods of iron determination
GOST 25284.6−95
Group B59
INTERSTATE STANDARD
ZINC ALLOYS
Methods of iron determination
Zinc alloys. Methods for determination of iron
ISS 71.040.40
AXTU 1709
Date of introduction 1998−01−01
Preface
1 DEVELOPED by the Donetsk state Institute of non-ferrous metals (Danism); International technical Committee MTC 107
SUBMITTED to the State Committee of Ukraine for standardization, Metrology and certification
2 ADOPTED by the Interstate Council for standardization, Metrology and certification (EASC Protocol No. 7 of April 26, 1995)
The adoption voted:
| The name of the state |
The name of the national authority for standardization |
| The Republic Of Belarus |
Gosstandart Of Belarus |
| The Republic Of Moldova |
Moldovastandart |
| Russian Federation |
Gosstandart Of Russia |
| Ukraine |
Gosstandart Of Ukraine |
3 Resolution of the State Committee of the Russian Federation for standardization, Metrology and certification dated June 2, 1997 N 204 inter-state standard GOST 25284.6−95 was put into effect directly as the state standard of the Russian Federation from January 1, 1998
4 REPLACE GOST 25284.6−82
1 SCOPE
This standard applies to zinc alloys, and sets the atomic absorption and photometric methods for determination of iron in its mass fraction from 0.01 to 0.4% in the samples of these alloys.
2 NORMATIVE REFERENCES
The present standard features references to the following standards:
GOST 3118−77 hydrochloric Acid. Specifications
GOST 3760−79 Ammonia water. Specifications
GOST 4204−77 sulfuric Acid. Specifications
GOST 4461−77 nitric Acid. Specifications
GOST 4478−78 sulfosalicylic Acid 2-water. Specifications
GOST 6344−73 Thiourea. Specifications
GOST 10929−76 Hydrogen peroxide. Specifications
GOST 25284.0−95 Alloy zinc. General requirements for methods of analysis
3 GENERAL REQUIREMENTS
General requirements for methods of analysis according to GOST 25284.0.
4 ATOMIC ABSORPTION METHOD
4.1 the essence of the method
The method is based on dissolving the sample in hydrochloric acid and measuring the nuclear absorption of iron in the flame of acetylene-air at a wavelength of 248.3 nm.
4.2 Equipment, reagents and solutions
Atomic absorption spectrophotometer with the radiation source for iron.
Hydrochloric acid according to GOST 3118, diluted 1:1 and solution 2 mol/DM.
Hydrogen peroxide according to GOST 10929.
The restored iron metal or iron oxide (III) in the normative documentation.
Standard iron solution
Solution a: 0.5 g of iron metal or 0,7149 g of iron (III) oxide, pre-calcined at 500 °C for 30 min and cooled in a desiccator, dissolved in 50 cmof a solution of hydrochloric acid (1:1), add a few drops of hydrogen peroxide. The solution was boiled to destroy excess hydrogen peroxide, cooled, transferred to a volumetric flask with a capacity of 500 cm
, made up to the mark with water and mix.
1 cmof the solution contains 0.001 g of iron.
Solution B: 10 cmsolution And transferred to a volumetric flask with a capacity of 100 cm
, add 10 cm
solution (2 mol DM
) hydrochloric acid, made up to the mark with water and mix.
1 cmof a solution contains 0.0001 g jelly
for.
4.3 analysis
4.3.1 the sample of alloy weighing 1 g is placed in a beaker with a capacity of 300 cm, add 10 cm
of hydrochloric acid (1:1). After termination of the reaction dissolved add 1 cm
of hydrogen peroxide and boil for 5 min.
4.3.2 Solution was cooled, transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.
4.3.3 When the mass fraction of iron in excess of 0.1% in the volumetric flask with a capacity of 100 cmis placed 25 cm
of a solution obtained by 4.3.2, add 10 cm
solution (2 mol DM
) hydrochloric acid, made up to the mark with water and mix.
4.3.4 To build a calibration curve in five out of six volumetric flasks with a capacity of 100 cmeach placed 1,0; 3,0; 5,0; 7,0 and 10,0 cm
standard solution B. In each flask add 10 cm
of solution (2 mol DM
) hydrochloric acid, made up to the mark with water and mix.
The solution, in which iron is not introduced serves as a solution control experience.
4.3.5 sample Solution obtained in accordance with 4.3.2 or 4.3.3, solutions for constructing the calibration curve and control experience is sprayed into the flame of acetylene-air and measure the atomic absorption of iron at a wavelength of 248.3 nm.
According to the obtained values of the nuclear absorption of iron and their corresponding mass concentrations of iron to build a calibration curve in the coordinates: the value of atomic absorption — mass concentration of iron, g/cm.
Mass concentration of iron in solutions of the sample and the reference experiment is determined by the calibration schedule.
4.4 Processing of results
4.4.1 Mass fraction of iron , %, is calculated by the formula
where — mass concentration of iron in the sample solution found by the calibration schedule, g/cm
;
— mass concentration of iron in solution in the reference experiment, was found in the calibration schedule, g/cm
;
— the volume of the sample solution, cm
;
— the weight of the portion of sample or the mass of the sample in aliquote part of the sample, g
.
4.4.2 Discrepancy between the results of parallel measurements and the results of the analysis shall not exceed allowable (at confidence probability of 0.95) of the values given in table 1.
Table 1
Percentage
| Mass fraction of iron |
The absolute maximum discrepancy | |||||
| results of parallel measurements of iron |
the results of the analysis of iron | |||||
| From 0,01 to 0,03 incl. |
0,0025 |
0,005 | ||||
| SV. 0,03 |
« |
0,1 |
« |
0,006 |
0,012 | |
| « |
0,1 |
« |
0,2 |
« |
0,013 |
0,026 |
| « |
0,2 |
« |
0,4 |
« |
0,025 |
0,05 |
5 PHOTOMETRIC METHOD SULFOSALICYLIC ACID
5.1 the essence of the method
The method is based on the separation of iron from copper after dissolving the samples in hydrochloric acid, the formation of yellow colored complex compound of iron with sulfosalicylic acid in an ammonia solution and measuring the optical density of the solution of the compounds at a wavelength of 425 nm.
5.2 the Instrument, reagents and solutions
Spectrophotometer or photoelectrocolorimeter.
Hydrochloric acid according to GOST 3118, diluted 1:1, and a solution of 2 mol/DM.
Sulfuric acid according to GOST 4204.
Sulfosalicylic acid according to GOST 4478, a solution of 25 g/DM: 25 g sulfosalicylic acid dissolved in 1 DM
of water and filtered. In the absence of sulfosalicylic acid mix 135 g of sulfa-salicylic acid sodium 1 DM
of water, add 25 cm
of concentrated sulfuric acid, heated and stirred until complete dissolution.
Sodium, sulfosalicylate in the normative documentation.
Ammonia water according to GOST 3760.
Hydrogen peroxide according to GOST 10929.
The restored iron metal or iron oxide (III) in the normative documentation.
Standard iron solution
Solution a: prepared in accordance with 4.2.
1 cmof the solution contains 0.001 g of iron.
Solution B: prepared in accordance with 4.2.
1 cmof a solution contains 0.0001 g of iron
.
5.3 analysis
5.3.1 a sample of alloy weighing 1 g is placed in a beaker with a capacity of 300 cmand dissolved in 10 cm
of hydrochloric acid (1:1). The precipitate of copper is filtered through the filter medium density («white ribbon»), washed the precipitate several times with hot water collecting the filtrate and washings in a conical flask with a capacity of 300 cm
. To the filtrate add a few drops of hydrogen peroxide and boil for 10 minutes to destroy the excess oxidant. The solution was cooled, transferred to a volumetric flask with a capacity of 100 cm
.
5.3.2 When the mass fraction of iron in excess of 0.08% solution obtained in accordance with 5.3.1, adjusted to the mark with water and mix.
Aliquot part of the solution is 20 cmis placed in a volumetric flask with a capacity of 100 cm
.
5.3.3 To construct the calibration curve five out of six volumetric flasks with a capacity of 100 cmeach introduce 1,0; 3,0; 5,0; 7,0 and 9,0 cm
standard solution B.
5.3.4 the solutions obtained in accordance with 5.3.1 or 5.3.2 and 5.3.3, add, stirring, 15 cmsulfosalicylic acid, ammonia, to obtain a yellow color and then another 20 cm
of ammonia. The solution was topped to the mark with water and mix. After 10 minutes measure the optical density at a wavelength of 425 nm. Solution comparison is the solution of the reference experiment (the solution corresponding to 5.3.3, which is not added iron).
According to the obtained values of optical density and corresponding mass of iron to build a calibration curve in the coordinates: the optical density is the mass of iron,
5.4 processing of the results
5.4.1 Mass fraction of iron , %, is calculated by the formula
where is the mass of iron was found in the calibration schedule g;
— the weight of the portion corresponding to aliquote part of the solution,
5.4.2 Discrepancy between the results of parallel measurements and the results of the analysis shall not exceed allowable (at confidence probability of 0.95) of the values given in table 1.
6 PHOTOMETRIC METHOD WITH 1,10-FENANTROLINA
6.1 the essence of the method
The method is based on measuring the optical density of the solution of complex compounds of iron (II) with 1,10-fenantrolina formed at a pH of 1.6−1.8. The effect of copper thiourea eliminate.
6.2 Apparatus, reagents and solutions
Spectrophotometer or photoelectrocolorimeter.
Nitric acid according to GOST 4461.
Hydrochloric acid according to GOST 3118, solutions 1 mol/land 0.2 mol/DM
.
Hydrogen peroxide according to GOST 10929.
Thiourea according to GOST 6344, solution 100 g/DM.
1,10-fenantrolin hydrochloric acid, a solution of 30 g/DM.
The restored iron metal or iron oxide (III) in the normative documentation.
Standard iron solution
Solution a: prepared in accordance with 4.2.
1 cmof the solution contains 0.001 g of iron.
Solution B: 1 cmstandard solution And placed in a volumetric flask with a capacity of 100 cm
, made up to the mark with water and mix.
1 cmof solution B contains 0,00001 g glands
.
6.3 analysis
6.3.1 a sample of alloy weighing 1 g is placed in a beaker with a capacity of 400 cmand dissolved in 15 cm
of hydrochloric acid and 2 cm
of nitric acid. The solution was evaporated to dryness, the residue is dissolved by heating in 20 cm
of a hydrochloric acid solution (1 mol/DM
). The solution was cooled, transferred to a volumetric flask with a capacity of 100 cm
, made up to the mark with water and mix.
6.3.2 When the mass fraction of iron to 0.05% aliquot part of the solution is 5 cm,transferred to a volumetric flask with a capacity of 50 cm
, add 20 cm
of water, 10 cm
of a solution of thiourea and 10 cm
of a solution of 1,10-fenantrolina. The solution was topped to the mark with water and mix. A solution in which all chemical reagents are added, is solution comparisons.
6.3.3 When the mass fraction of iron from 0.05 to 0.25% of 20 cmof a solution obtained in 6.3.1, transferred to a volumetric flask with a capacity of 100 cm
, 16 cm add
hydrochloric acid solution (1 mol/DM
), made up to the mark with water and mix.
Aliquot part of the solution is 5 cm,transferred to a volumetric flask with a capacity of 50 cm
and then do as in
6.3.4 When the mass fraction of iron from 0.25 to 0.40% 10 cmof a solution obtained in 6.3.1, transferred to a volumetric flask with a capacity of 100 cm
, 18 cm add
hydrochloric acid solution (1 mol/DM
), made up to the mark with water and mix. Aliquot part of the solution is 5 cm,
transferred to a volumetric flask with a capacity of 50 cm
and then do as in
6.3.5 To construct the calibration curve in seven volumetric flasks with a capacity of 50 cmeach are placed 0; 0,5; 1,0; 1,5; 2,0; 2,5; 3,0 cm
standard solution B, add 5 cm
of hydrochloric acid solution (2 mol/DM
), water to a volume of 25 cm
, 10 cm
solution of thiourea, 10 cm
of a solution of 1,10-phenanthroline, made up to the mark with water and mix. Solution not containing iron, is solution comparisons
.
6.3.6 after 30 min measure the optical density of the sample solution and solutions for constructing the calibration curve at a wavelength of 490 nm in a cuvette with the thickness of the absorbing layer of 5 cm.
According to the obtained values of optical density and corresponding mass of iron to build a calibration curve in the coordinates: the optical density is the mass of iron, the iron Content in the sample find for the calibration schedule.
6.4 Processing of results
6.4.1 Mass fraction of iron , %, is given by
where is the mass of iron was found in the calibration schedule g;
— the weight of the portion in aliquote part of the solution,
6.4.2 divergence of the results of parallel measurements and the results of the analysis shall not exceed allowable (at confidence probability of 0.95) of the values given in table 1.
