GOST 23957.2-2003

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  ГОСТ 23957.2-2003

GOST 23957.2−2003 Zinc. Atomic absorption method for determination of tin

GOST 23957.2−2003

Group B59

INTERSTATE STANDARD

Zinc

ATOMIC ABSORPTION METHOD FOR DETERMINATION OF TIN

Zinc.
Atomic-absorption method for determination of tin

ISS 77.120.60
AXTU 1709

Date of introduction 2005−07−01

Preface

1 DEVELOPED by Eastern research mining and metallurgical Institute of nonferrous metals (VNIItsvetmet), the Interstate technical Committee for standardization MTK 504 «Zinc, lead"

2 INTRODUCED by Committee on standardization, Metrology and certification of the Ministry of industry and trade of the Republic of Kazakhstan

3 ACCEPTED by the Interstate Council for standardization, Metrology and certification (Protocol No. 24 dated 5 December 2003) was a standards Bureau MGS N 4774

The standard was accepted by voting:

4 by Order of the Federal Agency for technical regulation and Metrology dated December 9, 2004 No. 101-St inter-state standard GOST 23957.2−2003 introduced directly as a national standard of the Russian Federation from July 1, 2005

5 REPLACE GOST 23957.2−80

1 Scope

This standard establishes the atomic absorption method for the determination of tin at a mass fraction of from 0.0005% to 0.06%.

The method is based on measurement of the absorption of the analytical line of tin 224,6 nm with the introduction of the analyzed solution and compare solutions in the flame acetylene-air.

Zinc previously transferred into solution by acid decomposition. Tin is precipitated on iron hydroxide.

2 Normative references

The present standard features references to the following standards:

GOST 860−75 Tin. General specifications

GOST 1770−74 laboratory Glassware measuring glass. Cylinders, beakers, flasks, test tubes. General specifications

GOST 3118−77 hydrochloric Acid. Specifications

GOST 3760−79 Ammonia water. Specifications

GOST 4461−77 nitric Acid. Specifications

GOST 5457−75 Acetylene, dissolved and gaseous. Specifications

GOST 5817−77 tartaric Acid. Specifications

GOST 6709−72 distilled Water. Specifications

GOST 9849−86 iron Powder. Specifications

GOST 23957.1−2003 Zinc. Atomic absorption method for the determination of lead, cadmium, antimony, iron and copper

GOST 25336−82 Glassware and equipment laboratory glass. The types, basic parameters and dimensions

GOST 29169−91 (ISO 648−77) oils. Pipette with one mark

GOST 29227−91 (ISO 835−1-81) oils. Pipettes are graduated. Part 1. General requirements

3 General requirements

General requirements for method of analysis according to GOST 23957.1.

4 Apparatus, materials and reagents

Spectrophotometer atomic absorption of any brand.

The air is compressed under pressure from 2·10to 6·10PA (2 to 6 ATM.) depending on the device.

Acetylene in cylinders GOST 5457.

Nitrous oxide in cylinders according to the normative document,

Filters obestochennye «blue ribbon» at [1].

Conical flasks or beakers according to GOST 25336 capacity of 250, 400, 500 cm.

Flasks volumetric with one mark not lower than 2nd accuracy class according to GOST 1770 with a capacity of 100, 1000 cm.

Pipette with one mark according to GOST 29169.

Graduated pipettes according to GOST 29227.

Distilled water according to GOST 6709.

Hydrochloric acid according to GOST 3118 and a solution of 2 mol/DM.

Tin GOST 860 grade not lower than A1.

Iron powder restored brand MLB-1 according to GOST 9849, hydrochloric acid solutions of 2 and 10 g/l; prepared by dissolving 1 and 5 g of iron at 10 and 50 cmhydrochloric acid with a few drops of nitric acid and transferred to volumetric flasks with a capacity of 500 cm.

Ammonia water according to GOST 3760 and a solution of 2:3 (two parts of water of ammonia mixed with three parts water).

Nitric acid according to GOST 4461 and a solution of 1:1.

Tartaric acid according to GOST 5817.

A mixture of acids, containing 20 g/lof salt, 180 g/DMof nitrogen and 45 g/lof tartaric acid.

Solutions of known concentration.

Solution a: 1,000 g of tin metal is placed in a conical flask with a capacity of 250 cm, flow 50 cmof hydrochloric acid, cover the flask with a lid and leave for a day without heating to dissolve the tin.

The resulting solution was transferred into a measuring flask with volume capacity of 1000 cm, adjusted to the mark with water and mix.

1 cmof the solution contains 1 mg of tin.

Solution B: 10 cmsolution And transferred to a volumetric flask with a capacity of 100 cm, adjusted to the mark with water and mix.

1 cmof the solution contains 100 micrograms of tin.

Solutions comparison, containing 5, 10, 20, 40 and 60 mg/cmtin, is prepared from solutions A and B. To do this in 5 volumetric flasks with a capacity of 100 cmstand 5, 10, 20 cmsolution B and 4 and 6 cmof solution A. To each flask add 10 cmof a solution containing 10 g/DMof iron, and 17 cmof hydrochloric acid, adjusted to the mark with water and mix.

Note — it is permitted to use other reagents and materials, subject to the achievement of metrological characteristics, not inferior to the established in this standard.

5 analysis

Zinc enters the analysis in the form of chips.

The sample, selected according to the mass fraction of tin, placed in a beaker with a capacity of 400−500 cmand dissolved in nitric acid solution (table 1).


Table 1

If necessary, the solutions were heated until complete dissolution of zinc. The solution is diluted with water to a volume of 120 cm, add 5 cmof a solution containing 2 g/DMof iron, heated to 70 °C — 80 °C and poured ammonia (table 1), precipitation of iron hydroxide. Heated to coagulate the precipitate after 15−20 min, filtered through a filter priliva portions of 5−7 cm. The glass, which carried out the deposition, and the filter cake washed once with water. Funnel with a filter placed in a cylinder with a capacity of 15−20 cmand dissolve the precipitate in hot hydrochloric acid solution, pre-washing the glass, which carried out the deposition, this same solution of hydrochloric acid. The total volume of the solution in the cylinder should not exceed 10 cm.

When the mass fraction of lead of over 0.5%, the precipitate of hydroxides on the filter is dissolved in hot mixture of acids.

Measurement conditions selected in accordance with the used brand of the device using trendeleva burner and is enriched with acetylene flame (visible yellow flames, their size is determined by background fluctuations. The flow of acetylene was increased to until background fluctuations do not interfere with the measurement of the absorption line the tin).

Work on a calibration schedule or by «limiting solutions». The method of «limiting solutions» is to register the analytical signals of the determined elements in the analyzed solution and the two solutions comparisons, one of which has a smaller and the other larger analytical signal than the analytical signal of the designated elements in the analyzed solution.

When using atomic absorption spectrometer complete with computer processing of results of measurements of analytical signals and calculating results of the analysis provided by software and held in automatic mode without operator intervention.

Notes

1 allowed odnoschelevye burners subject to the achievement of the sensitivity of the determination of tin set this standard and metrological characteristics that are not inferior are shown in table 2.

2 you Can use the flame nitrous oxide-acetylene is subject to the achievement of metrological characteristics that are not inferior are shown in table 2.

6 processing of the results

6.1 Mass fraction of tin , %, is calculated by the formula

, (1)

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

 — the volume of the analyzed solution, cm;

 — the weight of the portion of the sample, mg;

 — conversion factor from mg to µg.

The result of the analysis taking the arithmetic mean obtained from two parallel definitions.

6.2 Allowable differences in the percent of the results of two parallel measurements ( — convergence) and the results of the two analyses (the reproducibility), accuracy of analysis results (a) shall not exceed the values given in table 2.


Table 2 — Standards of control and accuracy of the analysis results (at a confidence probability =0,95)

Percentage

The permissible discrepancy between two parallel definitions , %, and two analyses of the same sample , %, for the intermediate mass fraction is calculated by the formula:

; (2)

, (3)

where is the relative standard deviation of repeatability (of results of two parallel measurements);

 — the relative standard deviation of reproducibility (of results of two analyses of the same sample);

 — the average of results of two parallel determinations;

 — the arithmetic mean of the two analysis results;

=2,77 when =2, =0,95;

=2,77 when =2, =0,95.

The intermediate error values of the analysis results , the allowable discrepancy of the results of two parallel measurements and the two results of the analysis of the same sample can be determined by linear interpolation.