GOST 27973.0-88
GOST 27973.0−88 Gold. General requirements for methods of analysis (Change No. 1)
GOST 27973.0−88
Group B59
INTERSTATE STANDARD
GOLD
General requirements for methods of analysis
Gold.
General requirements for methods of analysis
AXTU 1709
Date of introduction 1990−07−01
INFORMATION DATA
1. DEVELOPED AND INTRODUCED the Main Directorate of precious metals and diamonds at the Council of Ministers of the USSR
DEVELOPERS
Yu. a. Karpov, Dr. chem. Sciences (head of subject); Small V. D., Cand. Fiz.-Mat. Sciences (head of subject)
2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from
The change in N 1 taken by the Interstate Council for standardization, Metrology and certification (minutes N 11 dated 25.04.97)
Was the Technical Secretariat of MGS N 2518
The adoption of the changes voted:
| The name of the state |
The name of the national authority for standardization |
The Republic Of Azerbaijan |
Azgosstandart |
The Republic Of Armenia |
Armastajad |
The Republic Of Belarus |
Gosstandart Of Belarus |
Georgia |
Gosstandart |
The Republic Of Kazakhstan |
Gosstandart Of The Republic Of Kazakhstan |
Kyrgyz Republic |
Kyrgyzstandart |
The Republic Of Moldova |
Moldovastandart |
Russian Federation |
Gosstandart Of Russia |
The Republic Of Tajikistan |
Tajikistandart |
| Turkmenistan |
The main state inspection of Turkmenistan |
| The Republic Of Uzbekistan | Standards |
3. INTRODUCED FOR THE FIRST TIME
4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced |
The number of the paragraph, subparagraph |
| GOST 12.0.004−90 |
17 |
| GOST 3118−77 |
11.1 |
| GOST 4461−77 |
11.1 |
| GOST 6709−72 |
11.1 |
| GOST 22159−76 |
11.1 |
| GOST 22864−83 |
17 |
| GOST 25336−82 | 11.1 |
5. Limitation of actions taken by Protocol No. 7−95 Interstate Council for standardization, Metrology and certification (ICS 11−95)
6. REVISED (June 1999) Change 1, approved in September 1997 (IUS 12−97)
1. This standard establishes General requirements for methods of analysis of gold with a mass fraction of gold is not less than 99.9%.
2. Sampling is carried out according to normative-technical documentation for this product.
3. For analysis and preparation of solutions used reagents qualifications not lower than h. d. a. and bidistillated water.
4. The purity of the metals used for the preparation of standard solutions needs to be not less than 99.9%.
5. Weighing of batches is carried out with the error not more than:
0.0002 g for methods based on pre-dissolving gold;
0.002 g — atomic-emission method (in the analysis of samples of arbitrary shape).
(Changed edition, Rev. N 1).
6. In the expression «diluted 1:1,1:2», etc. the first digits indicate the volume of the acid, or any solution, the second volume of the water.
7. The term «hot water» (solution) means that the water (solution) has a temperature of above 70 °C.
8. For tests used laboratory volumetric glassware is not below 2nd class of accuracy.
9. Allowed the use of other equipment, materials, utensils and reagents, subject to obtaining the metrological characteristics are not inferior to the specified in the standard methods of analysis.
10. Prior to analysis, the gold surface is cleaned; a portion of the sample (in the form of chips, strips, plates etc or in the form of a rod) is placed in a beaker with a capacity of 50−100 cm, add 10−20 cm
(for the rod and 50 cm
) of a solution of hydrochloric acid (1:1) and boiled for 5−10 min. the Solution is decanted and washed 6−7 times with water by decantation. Treated in the same way standard samples of composition of gold. In the case of the analysis of gold sponge or gold powder sample is pre-pressed in a steel mold and chemical cleaning are not subjected to. Allowed fusion of the sample in the bead.
11. In the absence of the passport or specifications in the analyzed sample is carried out a preliminary analysis of the gold content of the basic component. Analysis carried out by the gravimetric method based on the recovery of gold from hydrochloric acid solutions by hydrazine.
11.1. Equipment, reagents, materials
Analytical scale.
Muffle furnace with thermostatic control.
Electric stove with a closed spiral.
Glasses heat resistant capacity of 200 cmaccording to GOST 25336.
Nitric acid according to GOST 4461.
Hydrochloric acid according to GOST 3118.
Distilled water according to GOST 6709.
Hydrazine dihydrochloride according to GOST 22159, a solution of 50 g/DM.
11.2. Analysis
Weighed metal weighing 100−200 mg was placed in a beaker with a capacity of 200 cmand dissolve in low heat 10 cm
of a freshly prepared mixture of hydrochloric and nitric acids (3:1). After the dissolution of the metal solution is heated to remove oxides of nitrogen and diluted with 70 cm
of water. To the solution was added 20 cm
of a solution of hydrazine dihydrochloride and heated in a bath until complete coagulation of the precipitate of gold (the solution should be transparent). The solution was cooled and filtered through two filters «white ribbon». The filter cake is washed with hot water. The filter with the sediment was placed in pre-weighed porcelain crucible, dried, calcined at a temperature of 900 °C and weighed together with the crucible.
11.3. Processing of the results
Mass fraction of gold in the analyzed metal, expressed in percent, is calculated by the formula
where is the mass of the crucible with the sediment, g;
— weight of crucible, g;
— the weight of the portion of the metal,
12. Allowed a preliminary analysis of the gold content of the main component to carry out another method.
13. For constructing calibration graphs for atomic-emission analysis techniques allowed along with the state standard samples of composition of the gold industry-standard samples or standard samples of enterprises. To construct the calibration graphs when performing high precision analyses with differences in the evaluation of the quality use only the state standard samples of composition of gold.
14. The result of the analysis taking the arithmetic average of the results of parallel measurements, the maximum difference between them does not exceed the permissible differences calculated for a confidence level =0.95 and given in the appropriate standard methods of analysis.
15. The analysis is repeated, if the difference between the high and low results of parallel measurements and between the results of the analyses exceeds the value permissible discrepancies.
16. The accuracy of the analysis is controlled using the state standard samples (GSO) gold. The result of the analysis is considered correct if the absolute value difference was found between the mass fraction of the designated impurities in the standard sample and the corresponding certified value, specified in the certificate on a standard sample meets standards the accuracy of results of analysis of appropriate technique and does not exceed the value
where is the accuracy evaluation of GSO;
— the permissible discrepancy between the results of the analysis.
If the above ratio is not fulfilled, the tests according to this method cease to ascertain and eliminate the causes of the observed deviation.
17. Security requirements in the analysis of gold according to GOST 22864.
18. Mass fraction of main substance (gold) is determined by the difference between the 100% and the amount of the defined impurities.
