GOST 12072.4-79
INTERSTATE STANDARD
CADMIUMMethods for determination of copperCadmium. |
GOST |
Date of introduction 01.12.80
This standard sets the photometric method for the determination of copper (at a mass fraction of copper from 0.001% to 0.2%) and atomic absorption method (with a mass fraction of copper from 0.002% to 0.2%).
The standard fully complies ST SEV 918−78.
1. GENERAL REQUIREMENTS
1.1. General requirements for methods of analysis and security requirements — according to GOST 12072.0.
(Changed edition, Rev. No. 2).
2. PHOTOMETRIC METHOD
2.1. The essence of the method
The method is based on photometric determination of the content of copper and diethyldithiocarbamate lead in the region of wavelengths 430−455 nm or cuprizone at a wavelength of 600 nm.
(Changed edition, Rev. No. 3).
2.2. Apparatus, materials and reagents
Spectrophotometer or photoelectrocolorimeter of any kind for measurements in the visible region of the spectrum.
Hydrochloric acid according to GOST 3118, diluted 1:1.
Nitric acid according to GOST 4461, diluted 1:1.
Ammonia water according to GOST 3760.
Ammonium citrate on the other 6−09−01−768.
Ethyl alcohol according to GOST 18300, diluted 1:1.
Diethyldithiocarbamate sodium GOST 8864, a solution of 10 g/DM3.
Lead acetate according to GOST 1027.
Lead diethyldithiocarbamate in chloroform or carbon tetrachloride: 0.2 g of lead acetate dissolved in 20 cm3 of water, add 2 cm3 of a solution of sodium diethyldithiocarbamate. After 30 min the solution was transferred to a separatory funnel with a capacity of 250−300 cm3, was added 10 cm3 of chloroform or carbon tetrachloride and shaken for 1 min. Painted the extract discarded. In the funnel add 1 cm3 solution of sodium diethyldithiocarbamate, 10 cm3 of chloroform or carbon tetrachloride and shaken again for 1 min. If the extract is colored in yellow, the removal of copper is repeated to produce a colorless extract.
To the aqueous solution in the funnel add 20 cm3 of a solution of sodium diethyldithiocarbamate, and the precipitate of lead diethyldithiocarbamate dissolved by shaking in a separating funnel with portions of chloroform or of carbon tetrachloride at 100 cm3. After settling, the organic layer decanted into a volumetric flask with a capacity of 1 DM3, dilute to the mark with chloroform or carbon tetrachloride and stirred. The solution is poured for long-term storage in a bottle of dark glass with a glass stopper.
Chloroform or carbon tetrachloride according to GOST 20288.
Distilled water, purified from traces of copper: 500 cm3 of water is shaken in separating funnel for 1 min with 10 cm3 of a solution of lead diethyldithiocarbamate in chloroform or carbon tetrachloride. The supernatant organic layer discarded. Cleaning is repeated to produce the colorless organic extract.
Cuprizone on the other 6−09−14−1380, a solution of 5 g/DM3, a portion of the reagent a mass of 0.5 g is dissolved in 20 cm3 of hot ethanol, diluted 1:1, made up to 100 cm3 of hot ethanol, diluted 1:1, stirred and cooled.
Copper according to the GOST 859.
Standard solutions of copper.
Solution a: a sample of copper weighing dissolve 0,100 g in a conical flask with a capacity of 100 cm3 10 cm3 of a solution of nitric acid, diluted 1:1, and evaporated to dryness. Pour 5 cm3 of hydrochloric acid and again evaporated almost to dryness. The residue is dissolved in 20 cm3 of water, the solution was cooled, transferred to a volumetric flask with a capacity of 1 DM3, made up to the mark with water and mix.
1 cm3 of the solution A contains 0.1 mg of copper.
Solution B: measure 25 cm3 of solution A in a volumetric flask with a capacity of 250 cm3, made up to the mark with water and mix.
1 cm3 of a solution contains 0.01 mg of copper.
Indicator paper is universal in THAT 6−09−1181.
(Changed edition, Rev. No. 2, 3).
2.3. The analysis of lead diethyldithiocarbamate
2.3.1. The weight of cadmium weight of 1,000 g was placed in a conical flask with a capacity of 250 cm3, dissolve when heated in 20 cm3 of nitric acid, diluted 1:1, and evaporated to dryness. Add 5 cm3 of hydrochloric acid and evaporate the solution almost to dryness. To the residue poured 20 cm3 of hydrochloric acid, stirred and cooled. For the analysis we take the entire solution or part of it after diluting in a volumetric flask with a capacity of 100 cm3, in accordance with the table. 1.
Table 1
| Mass fraction of copper, % | Capacity volumetric flasks, cm3 | Aliquota part solution taken for analysis, cm3 |
The weight of the portion, relevant aliquote part solution, g |
The number added to dividing funnel salt acid, see3 |
| From 0.001 to 0.02 | - | The entire solution | 1,000 | - |
| SV. Of 0.02 «to 0.1 | 100 | 20 | 0,200 | 16 |
| «0,1» 0,2 | 100 | 10 | 0,100 | 18 |
Part of the solution or the entire solution placed in a separatory funnel with a capacity of 100 cm3, add appropriate amount of hydrochloric acid, add water to volume of 50 cm3, flow from burette 25 cm3 solution of lead diethyldithiocarbamate and perform the extraction of copper within 2 min. the Organic extract decanted into a dry flask with a capacity of 100 cm3, after 10 min, measure the optical density of colored solution into a suitable cuvette in the region of wavelengths 430−455 nm. As a solution comparison using the solution in the reference experiment.
The copper content set in the calibration schedule.
2.3.2. To build a calibration curve in nine out of ten separatory funnels with a capacity of 100 cm3 measure respectively 1,0; 2,5; 5,0; 7,5; 10,0; 12,5; 15,0; 17,5 and 20.0 cm3 of solution B (corresponding to 10, 25, 50, 75, 100, 125, 150, 175 and 200 mcg of copper), poured into each funnel with 20 cm3 of hydrochloric acid, made up to a volume of 50 cm3 of water, stirred, poured from a burette 25 cm3 of a solution of lead diethyldithiocarbamate and perform the extraction of copper as described in section
According to the obtained values of optical density of solutions and their corresponding grades of copper to build the calibration graph.
2.3.1,
2.4. The analysis cuprizone
2.4.1. Weighed samples of cadmium with a mass of 1.00 g is placed in a conical flask with a capacity of 250 cm3, dissolve when heated in 20 cm3 of nitric acid solution diluted 1:1, and evaporated to dryness. To the residue poured in 20 cm3 of water, stirred and cooled. For the analysis we take the entire solution or part of it after dilution in accordance with the table. 2.
Table 2
| Mass fraction of copper, % | The solution volume of the sample, cm3 | The solution volume selected for analysis, see3 |
| From 0.001 to 0.01 | - | The entire solution |
| SV. 0,01 «0,06 | 100 | 25 |
| «Of 0.06» to 0.1 | 100 | 10 |
| «0,1» 0,2 | 100 | 5 |
Part of the solution or the entire solution is placed in a volumetric flask with a capacity of 50 cm3, cautiously add the ammonia until the appearance of the precipitate of cadmium hydroxide, which is then dissolved by adding 1−2 drops of hydrochloric acid. Pour 5 cm3 of a solution of ammonium citrate and ammonia to pH 9 (universal indicator paper), cool and add 5 cm3 of a solution cuprizone. After 10 min top up to the mark with water, mix and after 60 min measure the light absorption at a wavelength of 600 nm, applying the appropriate cuvette. As a solution comparison using the solution in the reference experiment.
The copper content set in the calibration schedule.
(Changed edition, Rev. No. 3).
2.4.2. To build a calibration curve in seven of the eight volumetric flasks with a capacity of 50 cm3 measure respectively 1,0; 2,0; 4,0; 6,0; 8,0; 10,0; 12,0 cm3 of a standard solution B (equivalent to 10; 20; 40; 60; 80; 100; 120 mcg of copper) in each of the flasks poured in 5 cm3 of a solution of citrate of ammonium and then do as described in section
3. ATOMIC ABSORPTION METHOD
3.1. The essence of the method
The method is based on measurement of the absorption of the analytical line of copper at a wavelength of 324,7 nm with the introduction of the solution of the analyzed sample and calibration solutions in the air-acetylene flame. A portion of the cadmium pre-transferred into solution by acid decomposition.
3.2. Apparatus, materials and reagents
Atomic absorption spectrophotometer, and any brand with a radiation source of copper.
Air, compressed under a pressure of 2105 — 6105 PA (2−6 ATM).
Acetylene in the cylinder.
Nitric acid according to GOST 11125, diluted 1:1 and solution 2 mol/DM3.
Copper grade MO according to the GOST 859.
Standard copper solution: a sample of copper weighing 0,100 g was placed in a conical flask with a capacity of 100−250 cm3, pour 10 cm3 of nitric acid, heated to dissolution and removal of oxides of nitrogen, the solution was cooled and quantitatively transferred to a volumetric flask with a capacity of 1 DM3, made up to the mark with water and mix.
1 cm3 of solution contains 0.1 mg of copper.
(Changed edition, Rev. No. 3).
3.3. Analysis
3.3.1. The weight of cadmium weight of 1,000−2,500 g was placed in a conical flask with a capacity of 250 cm3, poured 15−20 cm3 of nitric acid, diluted 1:1, heated to dissolve the metal and remove oxides of nitrogen. Pour 20−25 cm3 of water, cooled, quantitatively transferred to a volumetric flask with a capacity of 100 cm3, made up to the mark with water and mix. The solution of the analyzed sample and calibration solutions is injected into air-acetylene flame and measuring the absorption of the analytical line of copper 324,7 nm according to GOST 12072.0.
(Amended, ISM, No. 1, 3).
3.3.2. To build a calibration curve in eleven of the twelve volumetric flasks with a capacity of 100 cm3 metered 0,5; 1,0; 2,0; 4,0; 6,0; 8,0; 10,0; 12,5; 15,0; 17,5 and 20.0 cm3 of a standard solution (corresponding to 0,5; 1,0; 2,0; 4,0; 6,0; 8,0; 10,0; 12,5; 15,0; 17,5 and 20.0 mg/DM3 of copper) in each of the flasks poured in 10 cm3 of a solution of nitric acid 2 mol/DM3, topped up to the mark with water and mix. Prepare only the necessary calibration solutions.
In the determination of one solution of thallium, lead, iron, zinc and Nickel in each of the above flasks should be added such amounts of standard solutions of these elements, which would correspond to their concentrations in the calibration solutions of standards. This should take into account the use of the hinge and framework of the calibration solutions when determining the content of zinc, iron and lead.
(Changed edition, Rev. No. 1).
4. PROCESSING OF THE RESULTS
4.1. The mass percent of copper (X), %, by photometric determination is calculated by the formula
where t is the weight of the portion corresponding to the selected aliquote part g;
t1 — the amount of copper found in the solution of the analyzed sample according to the calibration schedule, mcg.
4.2. The mass percent of copper (X), %, in atomic absorption the determination is calculated by the formula
where With1 — mass concentration of copper in the sample solution, mg/DM3;
With2 — mass concentration of copper in solution in the reference experiment, mg/DM3;
V — volume of the volumetric flask, cm3;
t — the weight of the portion,
(Changed edition, Rev. No. 1, 3).
4.3. Allowable absolute discrepancies in the results of parallel measurements and the results of the analysis shall not exceed the values given in table. 3.
Table 3
| Mass fraction of copper, % | The permissible divergence parallel definitions % |
The permissible discrepancy between the results analysis, % |
| From 0,0010 to 0,0020 incl. | 0,0003 | 0,0004 |
| SV. 0,0020 «0,0050 « | 0,0005 | About 0.0006 |
| «0,0050» 0,0100 « | 0,0010 | 0,0013 |
| «0,010» 0,040 « | 0,002 | 0,003 |
| «0,040» 0,100 « | 0,003 | 0,004 |
| «To 0.10» to 0.20 « | 0,01 | 0,02 |
(Changed edition, Rev. No. 3).
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Ministry of nonferrous metallurgy of the USSR
2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from
3. The standard fully complies ST SEV 918−78
4. REPLACE GOST 12072.4−79
5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced | Item number | The designation of the reference document referenced | Item number |
| GOST 859−2001 | 2.2, 3.2 | GOST 12072.0−79 | 1.1, 3.3.1 |
| GOST 1027−67 | 2.2 | GOST 18300−87 | 2.2 |
| GOST 3118−77 | 2.2 | GOST 20288−74 | 2.2 |
| GOST 3760−79 | 2.2 | THAT 6−09−1181−76 | 2.2 |
| GOST 4461−77 | 2.2 | THAT 6−09−14−1380−77 | 2.2 |
| GOST 8864−71 | 2.2 | THAT 6−09−01−768−89 | 2.2 |
| GOST 11125−84 | 3.2 |
