GOST 20996.12-2014

• gost-2099612-2014.pdf (344.44 KiB)
  ГОСТ 20996.12-2014

GOST 20996.12−2014 Selenium technical. Atomic absorption method for the determination of copper, iron, tellurium and lead

GOST 20996.12−2014

Group B59

INTERSTATE STANDARD

SELENIUM TECHNICAL

Atomic absorption method for the determination of copper, iron, tellurium and lead

Selenium for industrial use. Atomic-absorption method for determination of copper, iron, tellurium and plumbum

ISS 77.120.99

Date of introduction 2016−01−01

Preface

Goals, basic principles and main procedure of works on interstate standardization established in GOST 1.0−92 «interstate standardization system. Basic provisions» and GOST 1.2−2009 «interstate standardization system. Interstate standards, rules and recommendations on interstate standardization. Rules of development, adoption, application, renewal and cancellation"

Data on standard

1 DEVELOPED by the Open joint-stock company «Scientific-research and design Institute of enrichment and mechanical processing of minerals «URALMEKHANOBR» (JSC «uralmekhanobr»), Technical Committee for standardization TC 368 «Copper"

2 as AMENDED by the Federal Agency for technical regulation and Metrology (Rosstandart)

3 ACCEPTED by the Interstate Council for standardization, Metrology and certification (Protocol dated November 14, 2014 72-P)

The adoption voted:

4 by Order of the Federal Agency for technical regulation and Metrology of April 2, 2015 209-St inter-state standard GOST 20996.12−2014 introduced as the national standard of the Russian Federation from 1 January 2016.

5 REPLACE GOST 20996.12−82


Information about the changes to this standard is published in the annual reference index «National standards», and the text changes and amendments — in monthly information index «National standards». In case of revision (replacement) or cancellation of this standard a notification will be published in the monthly information index «National standards». Relevant information, notification and lyrics are also posted in the information system of General use — on the official website of the Federal Agency for technical regulation and Metrology on the Internet

1 Scope

This standard specifies the measurement of mass fraction of copper, iron, tellurium, lead by atomic absorption spectroscopy in technical selenium in the range of mass fraction, are presented in table 1.


Table 1

Percentage

2 Normative references

The present standard features references to the following international standards:

GOST 859−2014 Copper. Brand

GOST 1770−74 (ISO 1042−83, ISO 4788−80) Glassware volumetric laboratory glass. Cylinders, beakers, flasks, test tubes. General specifications

GOST 3118−77 Reagents. Hydrochloric acid. Specifications

GOST 3778−98 Lead. Specifications

GOST 4461−77 Reagents. Nitric acid. Specifications

GOST 5457−75 Acetylene, dissolved and gaseous. Specifications

GOST 6709−72 distilled Water. Specifications

GOST 9849−86 iron Powder. Specifications

GOST 20448−90 liquefied hydrocarbon Gases fuel for household consumption. Specifications

GOST 20996.0−2014 Selenium technical. General requirements for methods of analysis

GOST 24104−2001laboratory Scales. General technical requirements

_______________

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 29169−91 (ISO 648−77) oils. Pipette with one mark

GOST 29227−91 (ISO 835−1-81) oils. Pipettes are graduated. Part 1. General requirements

GOST ISO 5725−6-2003Accuracy (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 5725−1-2002.


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 in the annual information index «National standards» published as on January 1 of the current year, and the editions of the monthly information index «National standards» for 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.

3 Characteristics of measurement accuracy

The accuracy of measuring the mass fraction of copper, iron, tellurium, lead free complies with the characteristics given in table 2 (for P=0,95).

Limit values of repeatability and reproducibility of the measurement at a confidence level P=0.95 are shown in table 2.


Table 2 — Values of the measure of the accuracy, limits of repeatability and reproducibility of measurements of mass fraction of copper, iron, tellurium, lead at confidential probability P=0.95

Percentage

4 measurement Means, auxiliary devices, materials, solutions

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

spectrometer of atomic absorption with flame atomizer and the radiation sources for copper, iron, tellurium, lead;

— air compressor;

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

— heating glass-ceramic plate according to [1]* or similar, ensuring the heating temperature up to 350 °C;
________________
* POS. [1]-[2], see Bibliography. — Note the manufacturer’s database.


— volumetric flasks 2−100−2, 2−500−2, 2−1000−2 according GOST 1770;

— flasks KN-2−250−19/26 TCS GOST 25336;

pipettes not lower than 2nd accuracy class according to GOST and GOST 29169 29227.

When taking measurements, use the following products and solutions:

— air compressed under a pressure of 2·10-6·10PA;

— acetylene according to GOST 5457;

— propane-butane according to GOST 20448;

— distilled water according to GOST 6709;

— hydrochloric acid according to GOST 3118, diluted 1:1;

— nitric acid according to GOST 4461;

— lead according to GOST 3778, marks S0 and S1;

— copper according to the GOST 859;

— iron according to GOST 9849;

— tellurium metal, high purity [2].

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 measurement results, given in this standard.

5 Method of measurement

The method is based on measuring absorption of atomic resonance lines of copper, iron, tellurium, lead at the wavelengths indicated in table 3, after the introduction of the analyzed solution in the flame acetylene-air or propane-butane-air.


Table 3 — wavelengths

5.1 Preparation for measurement

5.1.1 Preparation of solutions of known concentration

5.1.1.1 Preparation of solutions of copper

In preparing the solution And the mass concentration of copper of 1 mg/cm: a sample of copper weighing 1 g is placed in a conical flask with a capacity of 250 cm, is dissolved in a volume of 25 to 30 cmmixture of nitric and hydrochloric acids (1:3) by boiling and the solution is evaporated to dryness. The residue is treated twice with a volume of 7 to 10 cmof hydrochloric acid, evaporating the solution every time dry. The dry residue is dissolved in a volume of 100 to 120 cmof hydrochloric acid diluted 1:1, boil to dissolve the salt, cooled and transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

In the preparation of a solution with a mass concentration of copper is 0.1 mg/cmof the sample solution And 50 cmplaced in a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix.

5.1.1.2 Preparation of solutions of iron

In preparing the solution And the mass concentration of iron is 1 mg/cm: a sample of iron weighing 1 g is placed in a conical flask with a capacity of 250 cm, is dissolved in a volume of 30 to 35 cmof a mixture of nitric and hydrochloric acids (1:3) under heating and the solution is evaporated to dry salts. Poured from 100 to 120 cmof hydrochloric acid diluted 1:1, boiled for 5−7 minutes, cool and transfer the solution into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

In the preparation of a solution with a mass concentration of iron to 0.1 mg/cmof the sample solution And 50 cmplaced in a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix.

5.1.1.3 Preparation of solutions of tellurium

In preparing the solution And the mass concentration of tellurium in 1 mg/cm: linkage of tellurium weighing 1 g is placed in a conical flask with a capacity of 250 cm, is dissolved in a volume of 20 to 25 cmof a mixture of nitric and hydrochloric acids (1:3) upon heating and boil to dissolve the sample and evaporate the solution to dryness. Go from 200 to 220 cmof hydrochloric acid, cooled and the solution transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

In the preparation of a solution with a mass concentration of tellurium 0.1 mg/cmof the sample solution And 50 cmplaced in a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix.

5.1.1.4 Preparation of solutions of lead

In preparing the solution And the mass concentration of lead of 1 mg/cma sample of lead with a mass of 1.0 g was placed in a conical flask with a capacity of 250 cm, flow 10 to 15 cmof nitric acid and evaporated to moist salts. Poured from 5 to 7 cmof nitric acid, transfer the solution into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

In the preparation of a solution with a mass concentration of lead of 0.1 mg/cmaliquot of 50 cmof solution A is placed in a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix.

5.1.2 Construction of calibration curve

In seven volumetric flasks with a capacity of 100 cmplaced: 0,2; 0,5; 1,0; 3,0; 4,0; 5,0 and 6.0 cmB solutions of copper, iron, lead and 0,5; 1,0; 5,0; 10,0; 15,0; 20,0 cmof a solution of tellurium. In each flask pour 1 to 2 cmof hydrochloric acid, made up to the mark with water and mix.

The resulting solutions injected into the flame of acetylene-air atomic absorption spectrophotometer and measure the absorption component at the appropriate wavelength (table 3).

Note — Concentrations of the calibration solutions are for guidance only and depend on the characteristics of the used atomic absorption spectrometer, the interval defined concentrations. For constructing a calibration curve allowed to use from 3 to 7 calibration solutions, but not less than 3.


The abscissa shows the delay of mass concentration defined component in the calibration solution, expressed in milligrams per cubic centimeter, and the y — axis the corresponding values of the analytical signals.

Note — it is allowed to Express the concentration of the calibration solutions in other mass units.

5.2 performance measurement

5.2.1 General requirements for method of measurements in accordance with GOST 20996.0.

5.2.2 Weighed mass of selenium from 1 to 5 grams (depending on the mass fraction of the component and the sensitivity of the instrument) is placed in a conical flask with a capacity of 250 cm, flow from 40 to 50 cmmixture of nitric and hydrochloric acids (1:3) and dissolved by heating to obtain a volume of 3−5 cm. Pour 50 to 60 cmof water and boil for 5−7 minutes, cool and transfer the solution into volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

The analyzed solution is injected into the flame of acetylene-air atomic absorption spectrophotometer and measure the absorption component at the appropriate wavelength (table 3). The absorbance of each solution is measured at least twice and for calculating take arithmetic mean value. When changing solutions, the spray system was washed with water to obtain the zero readings.

The recommended maximum value of measured absorbance of approximately 0.5 units. If necessary to reduce its value is allowed to carry out measurements at less sensitive wavelengths or deploy the burner.

The found value of the absorbance of the analyzed solution minus the absorbance of the blank solution experience find the mass concentration of the component defined by the calibration schedule. If the concentration of the analyte in the test solution exceeds the concentration in solutions to construct the calibration curve (the value of absorbance of the analyzed solution above absorption of the last points of the graph), carried out a dilution of the test solution. For this, an aliquot of the analyzed solution is placed in a flask with a capacity of 100 cm, pour the hydrochloric acid to create the acidity of 5% by volume, made up to the mark with water and mix.

Be used for the atomization of sample flame propane-butane-air, if the differences between parallel determinations match those listed in table 2.

6 Processing of measurement results

6.1 Mass fraction of component X, %, is calculated by the formula

, (1)

where is the mass concentration of the component was found in the calibration schedule µg/cm;

V — total volume of solution in a volumetric flask, cm;

 — the volume of the analyzed solution after dilution, cm;

 — volume aliquot of the solution, cm;

m — mass of sample selenium,

6.2 For the measurement result taking the arithmetic mean of two parallel definitions, provided that the absolute difference between them in terms of repeatability does not exceed the value (at confidence probability P=0.95) repeatability limit r given in table 2.

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).

6.3 Differences between measurements obtained in two laboratories, should not exceed the values of the limit of reproducibility shown in table 2. In this case, the final result can be accepted their mean value. At default of this condition can be used the procedure set out in GOST ISO 5725−6.

Bibliography