GOST 851.3-93

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  ГОСТ 851.3-93

GOST 851.3−93 Magnesium primary. Methods for determination of Nickel

GOST 851.3−93

Group B59

INTERSTATE STANDARD

MAGNESIUM PRIMARY

Methods for determination of Nickel

Primary magnesium.
Methods for determination of nickel

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 74 interstate standard GOST 851.3−93 introduced directly as state standard of the Russian Federation from January 1, 1997

4 REPLACE GOST 851.3−87

5 REISSUE

INFORMATION DATA

REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

This standard specifies the extraction-photometric (mass fraction in Nickel from 0,0003% to 0,0030%) and atomic absorption (at a mass fraction of Nickel from 0.0005% to 0,0060%) methods for determination of Nickel in primary magnesium.

If there are differences in the analysis carried out by the photometric method.

1 General requirements

1.1 General requirements for methods of analysis GOST 25086.

1.2 Mass fraction of Nickel is determined from two parallel batches.

1.3 When building glazirovannogo graph each point build on the average result of the three definitions of optical density of the atomic absorption.

1.4 Permitted discrepancies in the results of the analysis of the same samples obtained by the two methods, calculated according to GOST 25086.

1.5 When placing the results of the analysis make reference to this standard, specify the method of determining, and method and results of control accuracy.

2 Extraction-photometric method for the determination of Nickel

2.1 the essence of the method

The method is based on the formation of complex compounds of Nickel with dimethylglyoxime, its extraction with chloroform and subsequent measurement of optical density of the extract.

2.2 the Instrument, reagents and solutions

The spectrophotometer or photoelectric colorimeter.

Nitric acid — according to GOST 4461, diluted 1:1.

Hydrochloric acid — according to GOST 3118, diluted 1:1.

Ammonia water according to GOST 3760.

Ammonium chloride — GOST 3773, a solution with a mass concentration of 250 g/DM.

Sodium citrate — according to GOST 22280, solution with a mass concentration of 100 g/DM.

Ethyl alcohol — GOST 18300.

Dimethylglyoxime — GOST 5828, ethanol solution with a mass concentration of 10 g/DM.

Chloroform according to the State Pharmacopoeia .

Paper litmus — beyond 6−09−3404.

Obezdolennyh filter «white ribbon» — on the other 6−09−1678.

Nickel GOST 849.

State standard samples made in accordance with GOST 8.315.

Standard solutions of Nickel:

Solution a: 0,200 g of Nickel dissolved in 15 cmof a hydrochloric acid solution and 5 cmof nitric acid when heated, is evaporated to dryness, then add 10 cmof hydrochloric acid and evaporated again. Evaporation again, then add 100 cmof the hydrochloric acid solution, 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 0.2 mg of Nickel.

Solution B: 5 cmsolution And placed in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix; prepare before use.

1 cmof a solution contains 0.01 mg

Nickel.

2.3 analysis

2.3.1 Sample weight of 2.0 g (at a mass fraction of Nickel from 0,0003% to 0,0010%) or 1.0 g (for the mass concentration of Nickel greater than 0.001%) is placed in a beaker with a capacity of 400 cm, moisten with water and add in small portions a solution of hydrochloric acid at the rate of 20 cmper 1.0 g of magnesium. After the violent reaction solution is heated until complete dissolution of the sample. Then cooled to room temperature, add 10 or 20 cmof a solution of ammonium chloride (for batches of magnesium with a mass of 1.0 g and 2.0 g, respectively) and 10 cmof a solution of citrate of sodium. Solution add water to a volume of 80 cm, neutralized with ammonia solution on litmus paper to obtain a slightly alkaline reaction, cooled to room temperature, transferred into a separating funnel with a capacity of 200−250 cm, add 3 cmof a solution dimethylglyoxime, 6 cmof chloroform and shaken for 2 min.

The solution is kept for delamination for 1−2 minutes, then drain the chloroform extract in a dry test-tube with a glass stopper. Re-extraction was carried out for 1 min with 5 cmof chloroform. The extract is decanted into the same vial. The mixture of the extracts was filtered through a dry filter paper and measure its optical density at a wavelength of 360 nm.

Solution comparison is the solution of the control ops

TA.

2.3.2 Construction of calibration curve

To build a calibration curve in five of the six separatory funnels with a capacity of 200−250 cmis placed 0,5; 1,0; 2,0; 3,0; 4,0 cmstandard solution B, which corresponds to 0,005, 0,010; 0,020; 0,030; 0,040 mg of Nickel. Solution sixth separating funnel is a solution of the reference experiment. To each funnel add 70 cmwater, 5 cmof a solution of sodium citrate, 2−3 drops of solution of ammonia, 3 cmsolution dimethylglyoxime, 6 cmof chloroform, and then do as described in 2.3.1.

Solution comparison is the solution of the reference experiment.

According to the obtained values of optical density calibration curve built in accordance with GOST 25086.

2.4 Processing of results of analysis

2.4.1 Mass fraction of Nickel () in percent is calculated by the formula

, (1)

where is the mass of Nickel in sample solution, found by calibration schedule g;

 — the weight of the portion,

2.4.2 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

2.4.3 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 carry out accuracy control additives in accordance with GOST 25086.

Additives is a standard solution B.

3. Atomic absorption method for the determination of Nickel

3.1 the essence of the method

The method is based on measuring atomic absorption of Nickel at a wavelength of 232 nm in the electrothermal atomization mode.

The determination is carried out by standard addition.

3.2 Equipment, reagents and solutions

Spectrophotometer atomic absorption equipped with graphite atomizer, a source of excitation of spectral lines of Nickel.

Microspec with a capacity of 2 µm.

Argon — GOST 10157.

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

Nickel GOST 849.

State standard samples made in accordance with GOST 8.315.

Distilled water — according to GOST 6709.

Standard solutions of Nickel:

Solution a: prepared according to 2.2.

Solution B: 1 cmof solution A is placed in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix; prepare before use.

1 cmof solution contains 2 mcg of Nickel.

Solution: 1 cmof solution A is placed in a volumetric flask with a capacity of 200 cm, made up to the mark with water and mix; prepare before use.

1 cmof the solution contains 1 µg of Nickel

.

3.3 analysis

3.3.1 Sample the sample weight of 0.5 g was placed in seven glasses with a capacity of 300 cm. Moisten with water and add to every glass in small portions to 10 cmof hydrochloric acid. The dissolution is carried out at room temperature. After complete dissolution of batches of the solutions were transferred to volumetric flasks with a capacity of 50 or 100 cm(table 2).

Table 2

In six of the seven volumetric flasks with a solution of the sample add 2,5; 5,0; 7,5; 10,0; 12,5; 15,0 cmstandard solution a or B (see table 2), which corresponds to the mass concentration of added Nickel 0,05; 0,10; 0,15; 0,20; 0,25; 0,30 µg/cm.

The solutions in all flasks is poured to the mark with water and mix.

To prepare the solution in the reference experiment in a volumetric flask with a capacity of 50 or 100 cm(see table 2) was placed 10 cmsolution of hydrochloric acid, made up to the mark with water and mix.

Microspace injected into the graphite cuvette sequentially a solution of the reference experiment, the sample solution and in ascending concentrations of Nickel solutions containing additives of a standard solution of Nickel.

Measurement of atomic absorption of Nickel produced in the mode:

type of atomization is electro;

the lamp current, mA 10;

wavelength, nm — 232;

the slot width of the device, nm — 0,2;

the drying temperature of the first stage, 323−373;

Stage II, 373−473;

the drying time stage I, 5;

II stage — 5;

temperature ashing, 873;

time ashing, s — 20;

the temperature of the atomization, 2673;

the time of atomization, with — 5;

cleaning temperature, 2673;

cleaning — 2;

the speed of the argon cm/min — 200.

At the stage of atomization, the argon flow is stopped.

From the values of atomic absorption solutions containing additives of a standard solution of Nickel, subtract the value of atomic absorption of the sample solution. According to the obtained values of the difference between of atomic absorption and corresponding mass concentrations of added Nickel in µg/cmbuild a calibration curve, which find mass concentration of Nickel in solution in the reference experiment and the sample.

3.3.2 When the instrument is in automatic mode and held its graduations, hinge samples weighing 0.5 g were placed in four glasses with a capacity of 300 cmand then spend the dissolution as specified in 3.3.1. The solutions were transferred to volumetric flasks with a capacity of 50 or 100 cm(see table 2).

In three of the four volumetric flasks with a solution of the sample add 2,5; 8,5; 15,0 cmstandard solution a or B (see table 2), which corresponds to the mass concentration of the added Nickel 0,05; 0,17; 0,30 µg/cm.

The solutions in all flasks is poured to the mark with water and mix.

The solution in the reference experiment prepared as described in 3.3.1.

Microspace introduced into a graphite cuvette and the sample solution, and then in ascending order of the concentration of Nickel in solutions containing additives of a standard solution of Nickel, and carried out the calibration of an instrument.

Measurement of atomic absorption of Nickel is carried out in a mode on 3.3.1.

Then injected into the graphite cuvette, the solutions in the reference experiment and the sample and hold measurement of atomic absorption of Nickel in mode on 3.3.1.

After every 4−5 measurements of atomic absorption Nickel by graphite cuvette clear: microspace enter the water and spend the atomization process in a mode according to claim 3.3.1.

3.4 Processing of analysis results

3.4.1 Mass fraction of Nickel () in percent is calculated by the formula

, (2)

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

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

 — the volume of the sample solution, cm;

 — weight of charge, g

.

3.4.2. 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 3.

Table 3

3.4.3 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.