GOST 851.8-93

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  ГОСТ 851.8-93

GOST 851.8−93 Magnesium primary. Spectral method of determination of sodium and potassium

GOST 851.8−93

Group B39*
__________________________________________
* In the index «National standards» 2006
group B59. — Note the CODE.

INTERSTATE STANDARD

MAGNESIUM PRIMARY

Spectral method of determination of sodium and potassium

Primary magnesium.
Spectral method for determination of sodium and potassium

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, 20th, 1996 N 79 interstate standard GOST 851.8−93 introduced directly as state standard of the Russian Federation from January 1, 1997

4 REPLACE GOST 851.8−87

5 REISSUE

INFORMATION DATA

REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

This standard establishes a spectral method for the determination of sodium and potassium in primary magnesium.

The method allows to determine the mass fraction of sodium and potassium, from 0.001% to 0.02% of each.

Based on the excitation of atoms of sodium and potassium in a flame or in a high-frequency induction plasma, measuring the intensity of analytical signals and determination of mass fractions of elements using the calibration parameters.

1 General requirements

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

1.2 the result of the analysis be the arithmetic mean of results of two parallel measurements.

2 Equipment, reagents and solutions

Fiery spectrophotometer or photometer, providing the allocation of the resonance lines of sodium and potassium.

Plasma atomic emission spectrometer PS-4 of the company «BAIRD», or similar devices.

Acetylene — GOST 5457, cleaned with sulfuric acid.

Propane-butane according to GOST 20448.

Natural gas.

Argon — GOST 10157.

Distilled water — according to GOST 6709.

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

Sodium chloride — according to GOST 4233.

Potassium chloride — according to GOST 4234.

Magnesium metal brand Mg95 at ND with a mass fraction of sodium and potassium less than 0.001%.

Standard sodium and potassium solutions:

Solution a: 0,635 g of sodium chloride and 0,477 g of potassium chloride, previously dried at a temperature 378−388 K, dissolved in 50 cmof water, transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix; fit for use for 6 months.

The solution was stored in a plastic container.

1 cmof solution A contains 2.5 mg of sodium and potassium.

Solution B: 5 cmsolution And placed in a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix; prepare before use.

1 cmof solution B contains 0,0125 mg of sodium and potassium.

A solution of magnesium chloride.

100 g of magnesium was placed in a quartz glass with a capacity of 2000 cm, made up of 50 cmof water and carefully, by small portions add a solution of hydrochloric acid until complete dissolution of magnesium (consumed about 1600 cmof hydrochloric acid). The solution was then evaporated to obtain the wet salts, the precipitate is dissolved in water, transferred to a volumetric flask with a capacity of 2000 cm, made up to the mark with water and mix; fit for use for 6 months.

The solution was stored in a plastic container.

1 cmof the solution contains 0.05 g of magnesium.

3 analysis

3.1 Sample weighing 2.5 g placed in a beaker with a capacity of 200 cm, is poured 10 cmof water and carefully, in small portions add 40 cmof hydrochloric acid. After complete dissolution of the sample solution transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix, then do as specified in 3.3 and 3.4.

3.2 To construct the calibration graphs in eight volumetric flasks with a capacity of 100 cmare placed 50 cmof a solution of magnesium. In seven of the eight flasks poured 2,0; 4,0; 6,0; 10,0; 20,0; 30,0; 40,0 cmof solution B, which corresponds to 0,001; 0,002; 0,003; 0,005; 0,010; 0,015 and 0.020 mass fraction of sodium and potassium in percent. All the bottles topped up to the mark with water and mix. The eighth solution of the flask is a solution of the reference experiment.

3.3 Solutions with the help of compressed air, in the form of a fine suspension of the aerosol fed into the flame of the burner flame spectrophotometer and photometric, first in the order of increasing mass fraction of sodium and potassium, and then in the reverse sequence, spraying after each determination the water.

3.4 When performing analysis on the plasma spectrometer solutions in the order shown in 3.3, serves in an induction plasma using argon. Measured under the following conditions of excitation and registration of the spectra: the output power of the HF generator — (1,2−1,3) kW; argon flow, transporting the aerosol of 0.7 DM/min; plasma — 12.0 DM/min; integration time — 3 seconds; number of integrations — 5; observation height 16 mm above the upper edge of the burner.

The wavelength of the analytical lines, nm:

sodium — 589,59;

potassium — 766,40.

3.5 obtained from the two parallel measurements the average values of the intensity of spectral lines for each solution and their corresponding weight fractions of sodium and potassium build the calibration graphs.

Construction of calibration curve is produced before each analysis.

3.6 the use of other analytical lines of the modes and excitation spectra, as well as changes to the procedure of sample preparation 3.1 for the purpose of concentrating the samples, subject to obtaining the metrological characteristics meet the requirements of this standard.

4 processing of the results of the analysis

4.1 Mass fraction of sodium () and potassium () in percent is calculated by the formula

,

where  — mass fraction of sodium or potassium in the sample solution found by the calibration schedule, %;

 — mass fraction of sodium or potassium in solution in the reference experiment, was found in the calibration schedule, %.

4.2 Standards of accuracy of analysis results

Discrepancies between the results of parallel measurements () and the results of two tests performed in different conditions () shall not exceed (at p = 0.95) of the values given in table 1. The error analysis results (at p = 0.95) does not exceed the limit given in table 1.

Table 1

4.3 Control of accuracy of analysis results

Control the accuracy of the results of the analysis carried out by the method of additives in accordance with GOST 25086.

Additives is a standard solution A or B.

To control the accuracy of analysis results can be used by the state standard samples in accordance with GOST 8.315.