GOST 20996.0-82

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  ГОСТ 20996.0-82

GOST 20996.0−82 Selenium technical. General requirements for methods of analysis (Change No. 1)

GOST 20996.0−82*

Group B59

INTERSTATE STANDARD

SELENIUM TECHNICAL

General requirements for methods of analysis

Selenium. General requirements for methods of analyses

AXTU 1709

Date of introduction 1983−07−01

Resolution of the USSR State Committee on standards of 22 June 1982, N 2481 date of introduction is established 01.07.83

Limitation of actions taken by Protocol No. 7−95 Interstate Council for standardization, Metrology and certification (ICS 11−95)

REPLACE GOST 20996.0−75

* PUBLISHING (may 2000) with amendment No. 1, approved in December 1987 (IUS 3−88)

1. This standard establishes General requirements for methods of analysis of technical selenium and safety requirements when performing analyses.

2. The selection and preparation of samples for selenium analysis performed according to GOST 10298−79.

3. Mass fraction of selenium, iron and aluminium determined in parallel in three batches, the mass fraction of the remaining impurities in two batches.

4. Along with the analysis in the determination of impurities in technical selenium under the same conditions is carried out two test experience appropriate methods of analysis for inclusion in the amendments result in contamination of the reagents by subtracting the value of the reference experience from the result of the determination of a component in the analysis of samples or the conduct of the determination in relation to control experience.

5. For the results analysis be the arithmetic mean of results of parallel measurements, the maximum difference between them does not exceed the values permitted discrepancies listed in the relevant standard methods of analysis for the relevant ranges of the mass fraction of the designated component at a confidence level of 0.95.

If discrepancies in the results of parallel measurements exceed the permitted amount, the determination must be repeated. The numerical values of analysis results needs to contain the last significant digit in the same category, which is the last significant digit of the numerical values of the permissible differences of the results of determination.

4, 5. (Changed edition, Rev. N 1).

6. Weighting of the sample, precipitation during the analysis of the starting materials used for preparation of standard and titrated solutions, is needed with the maximum error of 0.0002 g.

7. For analysis and the preparation of solutions of reagents using distilled water according to GOST 6709−72 and reagents qualification not lower than h. d. a., if the standards are not specified a different degree of purity.

8. 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 substances used for dilution. If no dilution is specified, it should be borne in mind concentrated acids or ammonia.

9. The expression «hot water (a solution)» means that the liquid has a temperature of 70−90 °C, «warm water (or solution)» temperature of 40−70 °C.

10. Laboratory measuring equipment (pipettes, burettes, volumetric flasks, etc.) should correspond to GOST 1770−74 and other regulatory documents.

11. When the photometric and atomic absorption definitions necessary to build the calibration graphs, the x-axis which is the value of the mass fraction of the designated component and the y — axis- optical density of the corresponding solutions.

To construct the calibration graphs requires at least five points that need to be evenly distributed across the measuring range, the maximum and minimum values of the measurement set the measurement range limits.

12. Caption solutions establish not less than three batches of a basic substance, expressed in grams of ingredient per 1 cmof the solution and counting with accuracy to at least the third significant digit, control at least once per month.

13. For the preparation of standard solutions used a metal containing a main component at least 99.9%, or their oxides, or nitrate, carbonate salt. The method of preparation of standard solutions — according to GOST 4212−76.

14. Control of the correctness of the results of the analysis carried out with the help of standard samples of composition of the technical method or selenium additives.

When using standard samples the results of the analysis are considered valid, if the ratio

,

where is the arithmetic average of the reproduced value of the mass fraction, %;

 — certified characteristic mass fraction of the component in technical selenium, %;

allowable discrepancy between the results of parallel measurements, %.

When using the addition method additive should be 2−3 times higher than the mass concentration determined by the impurity in the sample (), and if the lower limit is determined by concentration of the additive should be 2−3 times the value .

The results of the analysis are considered valid, if the ratio

,

where is the arithmetic average of the reproduced value of the mass fraction of additives, %;

 — mass fraction of additives, %;

and  — the permissible discrepancy of the results of the parallel analyses of the component in the sample and in the sample with the additive %.

The periodicity of verification of results of analysis according to the normative document.

11−14. (Changed edition, Rev. N 1).

15. Safety requirements

15.1. Placement and storage of chemicals, samples of selenium and other materials used in the analyses and which are hazardous and harmful properties, and their use must comply with regulations on their production and application.

15.2. Sample technical selenium entering the analysis should be stored in packages of thick paper according to GOST 2228−81 or in cups for weighing according to GOST 25336−82 in a special Cabinet or box, equipped with ventilation systems according to GOST 12.4.021−75.

15.1, 15.2. (Changed edition, Rev. N 1).

15.3. Laboratory facilities in which to run the chemical analysis technical selenium, must be equipped with ventilation systems according to GOST 12.4.021−75, which provides a clean air working area in accordance with the requirements of GOST 12.1.005−88.

15.4. Laboratory facilities in which the work is performed in the analysis of the chemical composition of technical selenium, should be provided with fire extinguishers TOU-10 and OU-8 at ND.

(Changed edition, Rev. N 1).

15.5. All the operations of chemical analysis (sample dissolution, precipitation, extraction, etc.) associated with the release of toxic vapors or gases, shall be carried out in boxes equipped with local suction device.

15.6. When conducting technical analysis of selenium in workplace air can be harmful substances maximum allowable concentration should not exceed concentrations specified in the table.

(Changed edition, Rev. N 1).

15.7. Control of content of harmful substances in the air of working zone is carried out according to GOST 12.1.007−76.

15.8. Jobs to perform analyses should correspond to GOST 12.2.032−78 and GOST 12.2.033−78.

15.9. When working with toxic, corrosive, flammable, explosive reagents should observe security requirements outlined in the regulations.

15.10. When working with harmful and poisonous substances it is necessary to use means of protection according to GOST 12.4.011−89, individual means of protection (respirators according to GOST 12.4.004−74 or GOST 12.4.028−76, rubber gloves according to GOST 12.4.103−83, clothing for 27654−88 GOST and GOST 29058−91).

15.11. Overalls should be used according to the instructions on the procedure of issuing, storage and use of protective clothing, footwear and safety devices* approved by the USSR state Committee for labour and social Affairs.
______________
* Are «Rules of providing workers the special clothes, special footwear and other individual protection means» approved by the resolution of Ministry of labor dated 18.12.98 N 51. — Note the manufacturer’s database.

15.12. For disposal, disposal and neutralization of production waste analyses should be guided by the rules of safe work in the chemical laboratory and regulatory documents agreed upon with the sanitary and epidemiological service of the Ministry of health of the USSR.

15.13. When working with gas installations should be guided by GOST 12.2.008−75 and safety rules in the gas sector, approved by Gosgortekhnadzor of the USSR.

15.14. All electrical appliances and installations at the laboratory must conform to the rules of electrical devices approved by the state energy supervision Committee of the USSR.

Operation of electrical equipment and electrical installations used in the analysis process must be conducted in accordance with the rules of technical operation of electrical installations and safety rules at operation of electrical installations* approved by the state energy supervision Committee of the USSR, GOST 12.1.019−79, GOST 12.2.007.0−75.
_______________
* On the territory of the Russian Federation act «Interbranch Rules on labor protection (safety rules) for electrical installations» (SWEAT P M-016−2001, RD 153−34.0−03.150−00), approved by decree of the Ministry of labour and social development of the Russian Federation from January 5, 2001 N 3; the order of the Ministry of energy of the Russian Federation from December, 27th, 2000 N 163. — Note the manufacturer’s database.

15.15. Working in chemical laboratories should be provided specierum according to the «Rules of free issue of milk or other equivalent food products to workers and employees in factories, workshops, sections and other subdivisions with harmful conditions"* approved by the USSR state Committee for labour and social Affairs.
_______________
* On the territory of the Russian Federation there are «Rules and conditions of free issue of milk or other equivalent food products to the workers occupied on works with harmful working conditions», approved by decree of the Ministry of labor of Russia from March 31, 2003 N 13. — Note the manufacturer’s database.

15.16. To work in chemical and spectral lab allowed a person trained in the requirements of safe work in laboratories according to GOST 12.0.004−90.