GOST 851.11-93

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  ГОСТ 851.11-93

GOST 851.11−93 Magnesium primary. Method for determination of tin

GOST 851.11−93

Group B59

INTERSTATE STANDARD

MAGNESIUM PRIMARY

Method for determination of tin

Primary magnesium.
Method for determination of tin

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, # 82 interstate standard GOST 851.11−93 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 sets the photometric method for the determination of tin (with mass fraction of tin from 0.001 to 0,030%) in primary magnesium.

The method is based on the formation in sulfuric acid medium at pH 3 colloidal solution of complex compounds of tin (IV) with phenylfluorone yellow-orange color, and then measure the optical density of the solution.

1 General requirements

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

1.2 Mass fraction of tin is determined from the two parallel batches.

2 Equipment, reagents and solutions

The spectrophotometer or photoelectric colorimeter.

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

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

Nitric acid — according to GOST 4461.

Ammonia water according to GOST 3760, a solution with a mass concentration of 250 g/DM.

Phenylfluorone (2, 3, 7, trioxo-9-(dimethyl-AMINOPHENYL)-fluoro-6) — on the other 6−09−05−289, a solution with a mass concentration of 0.3 g/DM: 0.03 g phenylfluorone was dissolved in ethanol, added with 1 cmof sulfuric acid solution (1:1) and topped up with ethanol to a volume of 100 cm. The reagent should have a pink color.

The polyvinyl alcohol — GOST 10779, a solution with a mass concentration of 10 g/DM, or gelatin food — according to GOST 11293, solution with a mass concentration of 5 g/DM, freshly prepared.

Sodium acetate 3-water — GOST 199.

Acetic acid — according to GOST 61, a solution with a mass concentration of 700 g/DM.

Buffer solution with a pH of 3: 20 g of sodium acetate are dissolved in 70 cmof water, filtered in a volumetric flask with a capacity of 200 cm, 48 cm, addacetic acid, made up to the mark with water and mix.

Tin — TU 6−09−2704.

State standard samples made in accordance with GOST 8.315.

Hydrogen peroxide — according to GOST 10929, solution with a mass concentration of 30 g/DM.

Of p-NITROPHENOL on the other 6−09−3973, a solution with a mass concentration of 1 g/DM.

Standard solutions of tin:

Solution a: 0,100 g of tin are dissolved in 10 cmof sulphuric acid and evaporated to fumes of sulfuric acid. The residue was cooled to room temperature, dissolved in 50 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 solution A contains 0.1 mg of tin.

Solution B: 1 cmof solution A is placed in a volumetric flask with a capacity of 100 cm, top up with sulphuric acid solution (1:9) to the mark and mix; prepare before use.

1 cmof the solution contains 1 ág of tin.

3 analysis

3.1 Sample weighing 1.0 g was placed in a beaker with a capacity of 300 cm, adding 25 cmof sulfuric acid solution (1:4), 2−3 drops of nitric acid, heated and boiled for 10 min. the Solution was cooled to room temperature, transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

Aliquot part of the solution is 2−10 cm(table 1) was placed in a volumetric flask with a capacity of 50 cm, add 1−2 drops of a solution of p-NITROPHENOL and neutralized with ammonia solution until yellow-green color. Then poured dropwise a solution of sulfuric acid (1:9) to the bleaching solution, add 1.4 cmof sulfuric acid solution (1:1), 1 cmof hydrogen peroxide solution, 10 cmbuffer solution, 5 cmsolution of polyvinyl alcohol 2.5 cm orgelatin solution, 1 cmof solution phenylfluorone, made up to the mark with water and mix. After 30 min, measure the optical density of the solution at a wavelength of 490 to 510 nm.

Solution comparison is the solution of the reference experiment.

Table 1

3.2 Construction of calibration curve

To build a calibration curve in six of the seven volumetric flasks with a capacity of 50 cmpour 1,0; 2,0; 3,0; 4,0; 5,0; 6,0 cmstandard solution B, which corresponds to 1,0; 2,0; 3,0; 4,0; 5,0; 6,0 mcg tin. In the seventh flask, a solution which is a solution of the reference experiment, pour 1 cmof sulfuric acid solution (1:9). To all flasks add water to a volume of 20 cm, 1−2 drops of a solution of p-NITROPHENOL, neutralized with ammonia solution until yellow-green color and then do as described in 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.

When building a calibration curve, each calibration point build on the average result of the three definitions of optical density.

4 processing of the results of the analysis

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

, (1)

where  — weight of tin in the sample solution found by the calibration schedule g;

 — total volume of sample solution, cm;

 — volume aliquote parts of a solution of the sample, cm;

 — the weight of the portion,

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 2.

Table 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 A.

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