GOST 20996.5-82

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  ГОСТ 20996.5-82

GOST 20996.5−82 Selenium technical. Method for the determination of organic substances (with Amendments No. 1, 2)

GOST 20996.5−82*

Group B59

INTERSTATE STANDARD

SELENIUM TECHNICAL

Method for the determination of organic substances

Selenium.
Method of organic materials determination

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)

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


The Change N 2, approved and promulgated by the Order of Rosstandart from 26.11.2014 No. 1761-St c 01.09.2015

Change No. 2 made by the manufacturer of the database in the text IUS N 3, 2015


This standard specifies the gravimetric method for the determination of organic matter (mass fraction of organic matter 0,01−0,35%).

The method is based on dissolution of organic impurities in ether or carbon tetrachloride, removing the excess solvent by heating and subsequent weighing of the sediment organic matter.

(Changed edition, Rev. N 1).

1. GENERAL REQUIREMENTS

1.1. General requirements for method of analysis according to GOST 20996.0−82.

1A. NORMATIVE REFERENCES

This standard uses the regulatory references to the following international standards:

GOST 1770−74 laboratory Glassware measuring glass. Cylinders, beakers, flasks, test tubes. General specifications

GOST 20288−74 Reagents. The carbon tetrachloride. Specifications

GOST 20996.0−82 Selenium technical. General requirements for methods of analysis

GOST 24104−2001* laboratory Scales. General technical requirements
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* On the territory of the Russian Federation GOST R 53228−2008 «Scales non-automatic actions. Part 1. Metrological and technical requirements. Test».


GOST 25336−82 Glassware and equipment laboratory glass. The types, basic parameters and dimensions

GOST ISO 5725−6-2002** Accuracy (trueness and precision) of methods and measurement results. Part 6. The use of precision values in practice
_______________
** On the territory of the Russian Federation GOST R ISO 5725−6-2002 «Accuracy (trueness and precision) of methods and measurement results. Part 6. The use of precision values in practice».


Note — When using this standard appropriate to test the effect of reference standards in the information system of General use — on the official website of the Federal Agency for technical regulation and Metrology on the Internet or published annually by the information sign «National standards» published as on January 1 of the current year and related information published monthly indexes published in the current year. If the reference standard is replaced (changed), when using this standard should be guided by replacing (amended) standard. If the reference standard is cancelled without replacement, then the situation in which the given link applies to the extent that does not affect this link.


Section 1A (Introduced later, Rev. N 2).

1B. CHARACTERISTICS OF INDICATORS OF MEASUREMENT ACCURACY

A measure of the accuracy of measuring the mass fraction of organic substances corresponds to the characteristics given in table 1 (if of 0.95).

Limit values of repeatability and reproducibility of measurements for a confidence probability of 0.95 is given in table 1.


Table 1

Percentage

Section 1B (Introduced later, Rev. N 2).

2. MEASUREMENT MEANS, AUXILIARY DEVICES, MATERIALS, SOLUTIONS

When performing measurements using the following measuring instruments and auxiliary devices:

— laboratory drying oven with thermostatic control, ensuring the heating temperature up to 250 °C;

— the stove is electric with a closed heating element for temperature up to 400 °C;

— special laboratory scales of accuracy class according to GOST 24104;

cylinders measuring stoppered 2−50−2 according GOST 1770;

— glasses-1−100 TCS according to GOST 25336;

— dryer 1−100 GOST 25336;

— bath water;

filters obestochennye [1] or similar.

When taking measurements, use the following products and solutions:

— carbon tetrachloride according to GOST 20288;

— diethyl ether medical.

Notes:

1. Allowed the use of other measuring instruments of the approved type, auxiliary devices and materials, technical and metrological characteristics are not inferior to mentioned above.

2. Allowed the use of reagents produced by other normative documents, provided that their metrological characteristics of the measurement results given in the measurement technique.

(Changed edition, Rev. N 2).

3. ANALYSIS

Selena weighed weighing 5 or 10 grams (depending on the mass fraction of organic substances) is placed in a measuring cylinder with a glass stopper with a capacity of 50 cm, flow 30−40 cmof ether or carbon tetrachloride and shaken intensively for 5 min.

After separation the organic layer was filtered through a loose folded filter into a previously dried and weighed glass with a capacity of 100 cm, wash the cylinder and filter with 2−3 servings 3−5 cmof solvent.

Then the beaker placed in a water bath and carefully evaporate the solution to dryness.

The glass is placed in a drying Cabinet and dried residue for 20−30 min at 100−105 °C.

After cooling, weigh the beaker with the residue. Drying the residue and weighing of the glass is continued until obtaining constant weight.

4. PROCESSING OF THE RESULTS

4.1. Mass share of organic substances () in percent is calculated by the formula

,

where is the mass of the glass residue, g;

 — the mass of the glass without residue, g;

 — weight of selenium,

4.2. The measurement results take the arithmetic mean of two parallel definitions, provided that the absolute difference between them in terms of repeatability does not exceed the values (with confidence probability of 0.95) limit of repeatability in table 1.

If the difference between the highest and lowest results of parallel measurements exceeds the limit value of the frequency of occurrence, perform the procedure described in GOST ISO 5725−6 (paragraph 5.2.2.1).

(Changed the wording. Izm. N 1, 2).

4.3. The absolute value allowable discrepancies between the two measurement results obtained in different laboratories, should not exceed the limit values for the reproducibility given in table 1 (at confidence probability of 0.95). At default of this condition can be used the procedure set out in GOST ISO 5725−6.

(Added, Rev. N 2).

BIBLIOGRAPHY

_______________
* Valid on the territory of the Russian Federation.

The one mentioned here, are not given. For additional information, please refer to the link. — Note the manufacturer’s database.

Bibliography (added, Rev. N 2).