GOST 851.9-93

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  ГОСТ 851.9-93

GOST 851.9−93 Magnesium primary. Methods for determination of titanium

GOST 851.9−93

Group B59

INTERSTATE STANDARD

MAGNESIUM PRIMARY

Methods for determination of titanium

Primary magnesium.
Methods for determination of titanium

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 80 interstate standard GOST 851.9−93 introduced directly as state standard of the Russian Federation from January 1, 1997

4 REPLACE GOST 851.9−87

5 REISSUE

INFORMATION DATA

REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

This standard sets the photometric and atomic absorption methods for the determination of titanium (with a mass fraction of titanium from 0.0005 to 0.020%) 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 titanium is determined from the two parallel batches.

1.3 When building a calibration curve each point build on the average result of the three definitions of optical density or 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 of accuracy of analysis results.

2 the Photometric method for the determination of titanium

2.1 the essence of the method

The method is based on the formation in an acidic medium Golden yellow complex compound of titanium with diantipyrylmethane and subsequent measurement of optical density of the solution.

2.2 the Instrument, reagents and solutions

The spectrophotometer or photoelectric colorimeter.

Nitric acid — according to GOST 4461.

Sulphuric acid — according to GOST 4204, diluted 1:4 and 1:9.

Hydrochloric acid — according to GOST 3118, diluted 1:1 and the solution with molar concentration of 1 mole/DM.

Ascorbic acid according to the State Pharmacopoeia , a freshly prepared solution with a mass concentration of 20 g/DM.

Copper sulfate 5-water — GOST 4165, a solution with a mass concentration of 50 g/DM.

Potassium preservatory — GOST 7172.

Diantipyrylmethane — on the other 6−09−3835, a solution with a mass concentration of 50 g/lin hydrochloric acid solution with molar concentration of 1 mole/DM.

State standard samples made in accordance with GOST 8.315.

Titanium dioxide — on the other 6−10−727.

Titanium grade BTi-0 — according to GOST 19807 or titanium sponge TG-90 — according to GOST 17746.

Standard solutions of titanium:

Solution a: 0,167 g of titanium dioxide, pre-calcined at a temperature of 1153−1193 K for 1 h, mixed with 3 g of potassium peacemaking and fused in a platinum crucible at a temperature 1063−1193 To produce a clear float.

The cooled melt is leached by heating in 300 cmof sulfuric acid solution (1:9) in a beaker with a capacity of 500 cmand poured into a measuring flask with volume capacity of 1000 cm, top up with sulphuric acid solution (1:9) to the mark and mix; fit for use for 6 months.

1 cmof solution A contains 0.1 mg of titanium.

Solution B: 0,100 g of titanium dissolved in 20 cmof sulfuric acid solution (1:4) when heated. After complete dissolution of sample, add nitric acid to the bleaching solution. Then the solution was evaporated until the appearance of sulphuric acid fumes, cooled to room temperature, add 100 cmof sulfuric acid solution (1:9), transferred into a measuring flask with volume capacity of 1000 cm, top up with sulphuric acid solution (1:9) to the mark and mix; fit for use for 6 months.

1 cmof a solution contains 0.1 mg of titanium.

Solution: 10 cmsolution A or solution B is poured into a measuring flask with a capacity of 100 cm, is poured a solution of hydrochloric acid 1 mol/DMup to the mark and mix; prepare before use.

1 cmof the solution contains 0,0

1 mg of titanium.

2.3 analysis

2.3.1 Sample weighing 1.0 g was placed in a beaker with a capacity of 300 cm, moistened with water and gently, in small portions add 20 cmof a hydrochloric acid solution (1:1). After the violent reaction of the wall of the beaker is washed with water and heated solution until complete dissolution of the sample. The solution was cooled to room temperature and transferred to a volumetric flask with a capacity of 100 cm, add the following solutions: 15 cmof hydrochloric acid (1:1), 1 cmof ascorbic acid (mass fraction of ascorbic acid should be at least ten times its quantity relative to the mass fraction of iron), two drops of solution of copper sulphate, mix and leave for 10 min Then add 10 cmof a solution diantipyrylmethane, made up to the mark with water and mix. After 40 min, measure the optical density of the solution at a wavelength of 400 nm. Solution comparison is the solution of the reference experiment.

2.3.2 Construction of calibration curve

To build a calibration curve in nine out of ten volumetric flasks with a capacity of 100 cmpour 0,5; 1,0; 2,0; 4,0; 6,0; 8,0; 10,0; 15,0; 20,0 cmstandard solution, which corresponds to 0,005; 0,010; 0,020; 0,040; 0,060; 0,080; 0,100; 0,150; 0,200 mg titanium, and top up with water to 20 cm. A tenth solution of the flask is a solution of the reference experiment. All flasks is poured at 15 cmof a hydrochloric acid solution (1:1), 1 cmof ascorbic acid, two drops of solution of copper sulphate and then do as described in 2.3.1.

Solution comparison is the solution of the reference experiment.

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

2.4 Processing of results of analysis

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

, (1)

where is the mass of titanium in the sample solution found by the 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 monitor the accuracy of analysis results by the method of additives in accordance with GOST 25086.

Additives is a standard solution B.

3 Atomic absorption method for the determination of titanium

3.1 the essence of the method

The method is based on measuring atomic absorption of titanium at a wavelength of 364,3 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 titanium.

Microspec capacity of 20x10m(20 µl).

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

Argon — GOST 10157.

Titanium grade VT1−0 — according to GOST 19807 or titanium sponge TG-90 — according to GOST 17746.

State standard samples made in accordance with GOST 8.315.

Distilled water — according to GOST 6709.

Standard solutions of titanium:

Solution a: 1,000 g of titanium dissolved in 100 cmof a hydrochloric acid solution under heating. After complete dissolution of the sample solution was cooled to room temperature, poured into a measuring flask with volume capacity of 1000 cm, add hydrochloric acid to the mark and mix; fit for use for 6 months.

1 cmof the solution contains 1 mg of titanium.

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

1 cmof solution B contains 5 µg of titanium.

Solution: 2.5 cmmortar And poured into 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 12,5 mcg ti

Tana.

3.3 analysis

3.3.1 Sample weight of 0.25 g or 0.5 g is placed in six beakers with a capacity of 300 cm. Then they moistened with water and added to each beaker in small portions at 5 or 10 cmof hydrochloric acid. After complete dissolution of batches of the solutions were transferred to volumetric flasks with a capacity of 100 or 250 cm(table 2).

Table 2

In five out of six volumetric flasks with a solution of the sample add 0,5; 1,0; 2,0; 3,0; 4,0 cmstandard solution B or C (see table 2), which corresponds to the mass concentration of the added titanium 0,025; 0,050; 0,100; 0,150; 0,200 mg/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 100 or 250 cmpour 5 or 10 cmof hydrochloric acid, made up to the mark with water and mix (see table 2).

Microstream sequentially injected into the graphite cuvette, the solution in the reference experiment, the sample solution in ascending concentration of titanium solutions containing additives of a standard solution of titanium. Measurement of atomic absorption is carried out in the mode:

The atomization stage is carried out in a current of argon.

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

3.3.2 In the case when the instrument is operated in automated mode and calibrated, sample of sample weight of 0.25 g or 0.5 g (see table 2) are 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 100 or 250 cm(see table 2).

In three of the four volumetric flasks with a solution of the sample add 0,5; 2,0; 4,0 cmstandard solution B or C (see table 2), which corresponds to the mass concentration of the added titanium 0,025; 0,100; 0,200 mg/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 titanium solutions containing additives of a standard solution of titanium, and conduct a calibration of an instrument. Measurement of atomic absorption 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, followed by measurement of atomic absorption of titanium in mode on 3.3.1.

After every 4−5 measurements of atomic absorption is carried out the purification of the graphite cuvette: microspace introduce water into it and produce the atomization process mode on 3.3.1.

3.4 Processing of analysis results

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

, (2)

where  — mass concentration of titanium in the sample solution, µg/cm;

 — mass concentration of titanium 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.