GOST 851.13-93

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  ГОСТ 851.13-93

GOST 851.13−93 Magnesium primary. Method of determining zinc

GOST 851.13−93

Group B59

INTERSTATE STANDARD

MAGNESIUM PRIMARY

Method of determining zinc

Primary magnesium.
Method for determination of zinc

ISS 77.120.20
AXTU 1709

Date of introduction 1997−01−01

Preface

1 DEVELOPED by the Ukrainian scientific-research and design Institute of titanium

INTRODUCED by Gosstandart of Ukraine

2 ADOPTED by the Interstate Council for standardization, Metrology and certification (Protocol No. 3 dated February 17, 1993)

The adoption voted:

3 Decree of the Russian Federation Committee on standardization, Metrology and certification from February 20, 1996 No. 84 of interstate standard GOST 851.13−93 introduced directly as state standard of the Russian Federation from January 1, 1997

4 INTRODUCED FOR THE FIRST TIME

5 REISSUE

INFORMATION DATA

REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

This standard establishes the atomic absorption method for the determination of zinc (at a mass fraction of zinc from 0.0005 to 0.020%) in primary magnesium.

The method is based on the measurement of atomic absorption of zinc in the flame of acetylene-air at a wavelength of 213,9 nm.

1 General requirements

1.1 General requirements to the method of analysis according to GOST 25086.

1.2 Mass fraction of zinc determined from the two parallel batches.

2 Equipment, reagents and solutions

Spectrophotometer of atomic absorption with the excitation source spectral lines of zinc.

Acetylene — GOST 5457.

Nitric acid — according to GOST 11125.

Hydrochloric acid — according to GOST 14261, diluted 1:1 and 1:99.

Zinc — according to GOST 3840.

State standard samples made in accordance with GOST 8.315.

Water bidistilled.

Standard solutions of zinc

Solution a: 0,100 g of zinc is dissolved in 30 cmof a hydrochloric acid solution (1:1) under heating. The solution was cooled to room temperature, transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix; fit for use for 6 months.

1 cmof solution A contains 0.1 mg of zinc.

Solution B: 10 cmsolution And placed in a volumetric flask with a capacity of 100 cm, is poured a solution of hydrochloric acid (1:99) to the mark and mix; prepare before use.

1 cmof a solution contains 0.01 mg of zinc.

Solution: 1 cmof solution A is placed in a volumetric flask with a capacity of 100 cm, is poured a solution of hydrochloric acid (1:99) to the mark and mix; prepare before use.

1 cmof the solution contains 1 mg of zinc.

3 analysis

3.1 Sample weighing 0.5 g were placed in a glass with a capacity of 200 cm, is poured 10 cmof water, 10 cmof hydrochloric acid (1:1) and lead dissolution initially at room temperature and then under heating on an electric stove.

After complete dissolution of the sample, add 3−4 drops of nitric acid and boil for 1−2 min. the Solution was cooled to room temperature, transferred to a volumetric flask with a capacity of 50 cm, made up to the mark with water and mix.

To prepare the solution in the reference experiment in a beaker with a capacity of 200 cmis placed 10 cmwater, 10 cmof hydrochloric acid (1:1), heated to boiling, add 3−4 drops of nitric acid and then do as above.

The solutions in the reference experiment and the sample is sprayed into the flame of acetylene-air and measure the atomic absorption at a wavelength of 213,9 nm.

Before measuring the atomic absorption of the sample solutions and the reference experiment is carried out construction of calibration curve or the calibration of an instrument if it is running in automated mode

.

3.2 Constructing the calibration graphs

When the mass fraction of zinc from 0.0005 to 0,0020% in six of the seven volumetric flasks with a capacity of 50 cmplaced 2,5; 4,0; 5,5; 7,0; 8,5; 10,0 cmstandard solution, which corresponds to the mass concentration of zinc 0,05; 0,08; 0,11; 0,14; 0,17; 0,20 µg/cm.

A seventh solution of the flask is a solution of the reference experiment.

When the mass fraction of zinc from 0.002 to 0,010% in five out of six volumetric flasks with a capacity of 50 cmis placed 1,0; 2,0; 3,0; 4,0; 5,0 cmstandard solution B, which corresponds to the mass concentration of zinc-0,2; 0,4; 0,6; 0,8; 1,0 µg/cm.

The sixth solution of the flask is a solution of the reference experiment.

When the mass fraction of zinc from 0.01 to 0.02% in six of the seven volumetric flasks with a capacity of 100 cmplaced 5,0; 6,0; 7,0; 8,0; 9,0; 10,0 cmstandard solution B, which corresponds to the mass concentration of zinc 0,5; 0,6; 0,7; 0,8; 0,9; 1,0 µg/cm.

A seventh solution of the flask is a solution of the reference experiment.

The solutions in all flasks is poured a solution of hydrochloric acid (1:99) to the mark, stirred, is sprayed into the flame of acetylene-air and measure the atomic absorption at a wavelength of 213,9 nm.

According to the obtained values of atomic absorption and corresponding mass concentrations of zinc in µg/cmbuild calibration charts in accordance with GOST 25086.

When constructing the calibration graphs, each point building on the average result of the three definitions of atomic absorb

tion.

3.3 calibration of the spectrophotometer

When the mass fraction of zinc from 0.0005 to 0,0020% in three of the four volumetric flasks with a capacity of 50 cmis placed 2,5; 6,0; 10,0 cmstandard solution, which corresponds to the mass concentration of zinc of 0.05; 0,12; 0,20 µg/cm.

The solution to the fourth flask is a solution of the reference experiment.

When the mass fraction of zinc from 0.002 to 0,010% in three of the four volumetric flasks with a capacity of 50 cmis placed 1,0; 3,0; 5,0 cmstandard solution B, which corresponds to the mass concentration of zinc-0,2; 0,6; 1,0 µg/cm.

The solution to the fourth flask is a solution of the reference experiment.

When the mass fraction of zinc from 0.01 to 0.02% in three of the four volumetric flasks with a capacity of 100 cmis placed 5,0; 7,5; 10,0 cmstandard solution B, which corresponds to the mass of zinc concentration 0,5; 0,75; 1,0 µg/cm.

The solution to the fourth flask is a solution of the reference experiment.

The solutions in all flasks is poured a solution of hydrochloric acid (1:99) to the mark, stirred, is sprayed into the flame of acetylene-air in sequence: first, the solution in the reference experiment, then the standard solutions in ascending order of zinc concentration and carry out the calibration of an instrument. Measurement of atomic absorption is carried out at a wavelength 213,9 nm.

4 processing of the results of the analysis

4.1 Mass fraction of zinc () in percent is calculated by the formula

,

where is the mass concentration of zinc in sample solution, µg/cm;

 — mass concentration of zinc in solution in the reference experiment, µ g/cm;

 — the volume of the sample solution, cm;

 — weight of charge, g

.

4.2 Standards of accuracy of analysis results

The values of the characteristics of error definitions: permitted discrepancies in the results of parallel measurements (the rate of convergence) and the results of the analysis of the same samples obtained in two laboratories or in the same, but in different conditions (a measure of reproducibility), and the margins of error definitions ( — accuracy rate) at a confidence level =0.95 is shown in table 1.

Table 1

4.3 Control of accuracy of analysis results

Control of accuracy of analysis results is carried out according to state standard sample in accordance with GOST 25086.

Allowed to monitor the accuracy of analysis results by the method of additives in accordance with GOST 25086.

Additives is a standard solution B or C.

4.4 When placing the results of the analysis make reference to this standard, and indicate method and results of control accuracy.