GOST R ISO 4943-2010

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  ГОСТ Р ИСО 4943-2010

GOST R ISO 4943−2010 Steel and cast iron. Determination of the copper content. Spectrometric method of atomic absorption in the flame

GOST R ISO 4943−2010

Group B39

NATIONAL STANDARD OF THE RUSSIAN FEDERATION

STEEL AND CAST IRON

Determination of the copper content. Spectrometric method of atomic absorption in the flame

Steel and iron. Determination of copper content. Flame atomic absorption spectrometric method

OKS 77.080.01
AXTU 0709

Date of introduction 2011−06−01

Preface

The objectives and principles of standardization in the Russian Federation established by the Federal law of 27 December 2002 N 184-FZ «On technical regulation», and rules for the application of national standards of the Russian Federation — GOST R 1.0−2004 «Standardization in the Russian Federation. The main provisions"

Data on standard

1 PREPARED AND SUBMITTED by the Technical Committee for standardization TC 145 «monitoring Methods of steel products» on the basis of authentic translation into the Russian language of the standard, referred to in paragraph 3

2 APPROVED AND put INTO EFFECT by the Federal Agency for technical regulation and Metrology, dated 22 October 2010 N 312-St

3 this standard is identical with ISO 4943:1985* «Steel and cast iron. Determination of the copper content. Spectrometric method of atomic absorption in the flame» (ISO 4943:1985 «Steel and cast iron — Determination of copper content — Flame atomic absorption spectrometric method»).
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* Access to international and foreign documents referred to here and hereinafter, can be obtained by clicking on the link. — Note the manufacturer’s database.

In applying this standard it is recommended to use instead of the referenced international standards corresponding national standards of the Russian Federation and interstate standards, details of which are given in Appendix YES

4 INTRODUCED FOR THE FIRST TIME


Information about the changes to this standard is published in the annually issued reference index «National standards», and the text changes and amendments — in monthly indexes published information «National standards». In case of revision (replacement) or cancellation of this standard a notification will be published in a monthly information index «National standards». Relevant information, notification and lyrics are also posted in the information system of General use — on the official website of the Federal Agency for technical regulation and Metrology on the Internet

1 Scope

This standard specifies spectrometric method of atomic absorption in the flame to determine the mass fraction of copper in the steel and iron in the range of 0.004% to 0.5%.

2 Normative references

The present standard features references to the following standards*:
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For dated references, only use the specified edition of the standard. In the case of undated references, the latest edition of the standard, including all revisions and amendments.

* The table of conformity of national standards international see the link. — Note the manufacturer’s database.

ISO 5725−1Accuracy (trueness and precision) of methods and measurement results. Part 1. General principles and definitions [ISO 5725−1, Accuracy (trueness and precision) of measurement methods and results — Part 1: General principles and definitions]
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This standard is introduced instead of the cancelled standard ISO 5725:1986 «Precision of test methods. Determination of repeatability and reproducibility of a standard method by interlaboratory tests» (ISO 5725:1986, Precision of test methods — Determination of repeatability and reproducibility for a standard test method by inter-laboratory tests) in terms of General principles and definitions.


ISO 14284Steel and iron. Selection and preparation of samples for determination of chemical composition (ISO 14284, Steel and iron — Sampling and preparation of samples for the determination of chemical composition)
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This standard is introduced instead of the cancelled standard ISO 377:1985 «Welding of steel. Selection and preparation of specimens and samples» (ISO 377:1985, Wrought steel — Selection and preparation of samples and test pieces) as regards the sampling and preparation of samples for chemical analysis.

3 the essence of the method

This method is based on dissolving an analytical sample in a mixture of hydrochloric, nitric and perchloric acids, spraying the solution into air-acetylene flame spectrometric measurement of the atomic absorption emission resonance line of 324,7 nm emitted by the lamp with hollow copper cathode.

4 Reagents

In the analysis, unless otherwise specified, use reagents of the established analytical purity with a very low copper content and only distilled water or water of equivalent purity.

Use, whenever possible, only freshly prepared distilled or deionized water.

4.1 high-purity Iron with a mass fraction of copper is less than 0.0005%.

4.2 a Mixture of hydrochloric and nitric acids

Mixed three volume parts of hydrochloric acid (of 1.19 g/cm), one volume part of nitric acid (1,40 g/cm) and two volume parts of water.

Prepare mixture immediately before use.

4.3 a Mixture of hydrochloric, nitric and perchloric acids

Mixed 20 cmof hydrochloric acid (of 1.19 g/cm), 55 cmof nitric acid (1,40 g/cm) and 75 cmof perchloric acid (1.54 g/cm).

Note — it is allowed to use and perchloric acid with a density of 1.67 g/cm.100 cmof perchloric acid (1.54 g/cm) equivalent to 79 cmof perchloric acid (1,67 g/cm).

4.4 Copper, standard solution

4.4.1 stock solution with a copper concentration of 1 g/DM

A sample of high purity copper (purity more than 99.95%) weight 1,000 g, measured with an accuracy of ±0.0001 g was placed in a beaker with a capacity of 400 cmand dissolved in 25 cmof nitric acid (1,40 g/cm, diluted 1:4). Beaker cover watch glass. When the suspension is completely dissolved, the solution was evaporated in a water bath prior to the deposition of salts. Salt dissolved in water, cooled the solution and transferred into a measuring flask with volume capacity of 1000 cm, is diluted to the mark with water and mix.

4.4.2 Standard solution with a copper concentration of 20 mg/DM

Placed 20.0 cmbasic solution (4.4.1) in a measuring flask with volume capacity of 1000 cm, is diluted to the mark with water and mix.

1 cmstandard solution contains 20 mcg of copper.

This standard solution is prepared immediately before use.

5 Instrument

The analysis used ordinary laboratory equipment and the following equipment.

5.1 Atomic absorption spectrometer

Lamp with hollow copper cathode; used in air and purified acetylene not containing water, oil and copper, to provide a sustainable, transparent, lean fuel flame.

Used atomic absorption spectrometer considered suitable for work if, after setting in accordance with 7.3.4, it provides the limit of detection and characteristic concentration, in good agreement with the values given by the manufacturer, and meets criteria of accuracy, is given in 5.1.1.

5.1.1 the Minimum precision

Expect the standard deviation of the ten values of absorbance of the most concentrated calibration solution. The standard deviation should not exceed 1.0% of the average value of absorption.

Expect the standard deviation of the ten values of absorption of the least concentrated calibration solution (except a zero solution). The standard deviation shall not exceed 0.5% of the average value of absorbance for the most concentrated calibration solution.

It is also desirable that the device meets the additional requirements specified in paragraphs 5.1.1.1. to 5.1.1.3.

5.1.1.1 Characteristic concentration

Characteristic concentration of copper in the matrix, similar (in composition), the final sample solution analytical sample, should be less than 0.10 µg/cmof copper.

5.1.1.2 detection Limit

Detection limits calculated as twice the standard deviation of ten measurements of the absorbance of a solution containing the corresponding element with the selected level of concentration giving absorbance slightly higher than the zero solution.

The limit of detection of copper in the matrix similar to the final sample solution analytical sample, should be less than 0.15 mg/cmof copper.

5.1.1.3. the linearity of the graph

The slope of the calibration curve for the top 20% concentration region, which is expressed as the change in absorbance should not be less than 0.7 the values of slope for the bottom 20% concentration region, which is expressed as a change in absorption, defined in the same way.

For the device with automatic calibration against two or more standard samples prior to analysis should be established, using the testimony of removals are higher requirements on the linearity of the graph.

5.2 accessories

It is recommended to use the recorder with strip chart and/or digital reader to assess criteria for 5.1.1 and for all subsequent measurements.

You can apply the extension of the scale as long as the observed noise does not exceed the error of the reader, and the expansion of the scale have to use for the values of absorption less than 0.1. If you need to apply the expansion of the scale, and the device has devices for reading the value of the coefficient of expansion of the scale, this value can be calculate by simple division of the values of absorption obtained by measuring the absorbance of a suitable solution, with extension and without extension of the scale.

6 Sampling

Sample preparation is carried out in accordance with ISO 14284 or other normative documents for cast iron, such as national standards.

7 analysis

Warning — Couple of perchloric acid is explosive in the presence of ammonia, vapour of nitrous acid and any organic materials.

The spray system and drainage system should be well washed from perchloric acid at the end.

Note — All glassware should first be washed in hydrochloric acid (of 1.19 g/cm, diluted 1:1) and then in water. The amount of copper present in the beakers and flasks can be checked by measuring the absorbance of distilled water, poured into a glass dish after it was acid washed.

7.1 Analytical linkage

Weigh 0,500 g of the test sample with an accuracy to 0.001 g.

7.2 Blank

A blank experiment is conducted in parallel with the analysis and the same procedure using the same quantities of all reagents.

7.3 analysis

7.3.1 Preparation of test solution

Put the analytical sample (7.1) in a beaker with a capacity of 250 cm. Small portions add 20 cmof a mixture of hydrochloric, nitric and perchloric acids (4.3), covered with a glass watch glass and gently heat up until will not stop the process of dissolution. Was evaporated until the appearance of white fumes of perchloric acid. At a temperature that ensures the run-off of condensate vapour of perchloric acid on the inner walls of the glass, evaporated 1 min.

Note — Samples that are poorly soluble in a mixture of hydrochloric, nitric and perchloric acids (4.3), is first dissolved in 10 cmof a mixture of hydrochloric and nitric acid (4.2).


After cooling, add 25 cmof water and heated slightly to dissolve the salts. Again cooled and quantitatively transferred to a volumetric flask with a capacity of 100 cm. Dilute to the mark with water and mix.

Filter the solution, decanter, through a dry filter paper medium density for separation of the precipitate, for example of graphite, silicon and/or tungsten acid, and the filtrate was collected in a dry beaker, rejecting the first portions of the filtrate.

If it is assumed that the copper content in the test sample exceeds the mass fraction of 0.1%, the solution should be diluted with water.

Transfer 20.0 cmof the resulting solution in a volumetric flask with a capacity of 100 cm, is diluted to the mark with water and mix.

Note — If the test solution the original solution to be diluted, so diluted and solution of the blank experience (7.2).

7.3.2 Preparation of the calibration solutions

Put (10±0,01) g of iron (4.1) into a glass with a capacity of 1 DM. Add small portions of 400 cmof a mixture of hydrochloric, nitric and perchloric acid (4.3) and gently heated until complete dissolution.

When dissolution is complete, evaporate until a white pair of perchloric acid. The pair leave to stand 1 min at this temperature, when it reaches sustainable irrigation white vapors of perchloric acid of walls of glass.

After cooling, add 100 cmof water and slightly heated to dissolve the salts. Again cool the solution and quantitatively transferred to a volumetric flask with a capacity of 500 cm. Dilute to the mark with water and mix.

7.3.2.1 Calibration solution with a mass fraction of copper is less than 0.1%

In a volumetric flask with a capacity of 100 cmeach placed at 25.0 cmof a solution of iron (7.3.2). Using a pipette or burette, add in flasks, respectively, 0 (zero solution); 2,5; 5,0; 10,0; 15,0; 20,0; 25,0 cmstandard solution of copper (4.4.2). Dilute to the mark with water and mix.

7.3.2.2 Calibration solution with a mass fraction of copper from 0.1% to 0.5%

In a volumetric flask with a capacity of 100 cmeach placed on 5.0 cmof a standard solution of iron (7.3.2). Using a pipette or burette, add in flasks, respectively, 0 (zero solution); 2,5; 5,0; 10,0; 15,0; 20,0; 25,0 cmstandard solution of copper (4.4.2). Dilute to the mark with water and mix.

Note — 1 cmof a standard solution of copper (4.4.2) diluted to 100 cm, equivalent to the mass fraction of copper equal 0,004%, in the case 7.3.2.1 and the mass fraction of copper equal to 0.02% in the case of 7.3.2.2.

7.3.3 setup of atomic absorption spectrometer

Characteristics of atomic absorption spectrometer are shown in table 1.


Table 1

If there are no manufacturer’s recommendations regarding the width of the gap, then the spectral lines of copper 324,7 nm is recommended to set a slit width of 0.3 to 1.0 nm.

Note — Must adhere strictly to the manufacturer’s recommendations and comply with the following security measures:

— to take into account the explosive nature of acetylene under the regulations, associated with its use;

to protect operator’s eyes from UV radiation with the use of a filter;

— to clear the head of the burner of soot, formed salts of perchloric acid and purified. Bad burner can cause flares;

— check filling the siphon with water.

7.3.4 optimization of the mode of operation of atomic absorption spectrometer

In preparing the device for use, you must follow the manufacturer’s instructions.

Once adjusted the lamp current, slit width and the flow of gas and lit the burner, sprayed water to obtain stable readings.

Set absorption to zero, spraying the zero solution (or 7.3.2.1 7.3.2.2).

Choose damping system (damping setting) or the integration time to obtain a sufficiently stable signal that satisfies the accuracy requirements of (5.1.1).

Regulate the flame so that it was slightly depleted fuel, and burner height was 1 cm below the light path. Alternately spray the calibration solution of the highest concentration and the zero solution, while adjusting the gas flow and the burner position (horizontal, vertical, and angled), as long as the difference in absorption values between the calibration solutions does not become maximum. Check whether displayed spectrometer at the desired wavelength.

Evaluate criteria for 5.1.1 in order to ensure that the device is prepared for measurement.

7.3.5 Spectrometric measurements

Apply this extension of the scale to the calibration solution of the highest concentration gave a deviation of almost the entire scale of the instrument. Repeatedly spray the calibration solutions in ascending order up until the readings of absorbance for each solution will not give a definite precision, which indicates the stability of the device. Choose two of the calibration solution («sandwich»), one of which shows the absorption a bit less, and the second is a bit more compared to the test solution. Spray these solutions first in ascending and then in descending order of concentration, and the test solution is sprayed between two of the calibration solutions, and in each case measure the magnitude of absorption relative to water. Again spray the whole set of calibration solutions.

It is established that this technique is not suitable for instruments with automatic calibration, which can accept only two of the calibration solution. In this case you should not use two «sandwich» of the calibration solution for the initial calibration, but it is possible to perform alternately with the controlled solution.

Calibration solutions sprayed repeatedly during the series of measurements. Clean burner as necessary if the results fail to meet the conditions of precision due to pollution.

Get the absorbance of each calibration solution.

Determine the absorbance of the test solution and the average absorbance of the blank experience.

Translate the values of the absorbance of the test solution and the blank experience in milligram per cubic centimeter of copper, using the calibration graph of (7.4).

7.4 Construction of calibration curve

You need to build a separate calibration curve for each measurement series and for each of the expected range of mass fraction of copper.

Before building the graph, determine the concentration (actual or apparent) of the zero solution in the calibration series. This concentration is obtained by drawing the graph of the absorption values of the first three calibration mixtures and extrapolation of the curve to the concentration axis. This value concentration (ug/cmof copper) was added to the concentration value of each calibration solution before application to the calibration graph.

Build a calibration curve in dependence of the values of absorption of the calibration solutions mass concentration of copper, expressed in milligrams per cubic centimeter. Compare the values of absorption for the two closest calibration mixtures with the schedule. If their evidence of absorption do not differ from the schedule more than they allow valid criteria of accuracy, then the values obtained for the test solution, are considered acceptable.

8 Processing of results

8.1 Method of calculation

Mass fraction of copper , %, is calculated by the formula

, (1)

where is the concentration of copper in the test solution obtained from the calibration curve (7.4) µg/cm;

 — the concentration of copper in the blank solution experience, µg/cm;

 — the dilution factor for 7.3.1:

1 — for samples with an estimated mass fraction of copper of 0.1% or less;

5 for samples with an estimated mass fraction of copper more than 0.1%;

 — the mass of the analytical sample,

8.2 Accuracy

Routine check of this method was conducted in eight laboratories for five different levels of copper content, and each laboratory conducted 4−5 definitions at each level.

Statistical processing of results was conducted in accordance with ISO 5725−1 at p = 0.95.

The data obtained showed a logarithmic dependence of the results of the analysis between the mass fraction of copper, limit of repeatability (convergence) and reproducibility limit in the range of mass fraction of copper from 0.02% to 5%. Part of the range given in table 2.


Table 2

Percentage

The difference between two single results found at identical test material by one analyst using the same equipment and performing the test within a short time interval will exceed the repeatability limit of an average of not more than one in 20 in the normal and proper operations techniques.

The difference between two single and independent results obtained by two executors in different laboratories on the same test material will exceed the reproducibility on average no more than one in 20 in the normal and proper operations techniques.

9 test report

The test report shall contain:

a) method used with reference to this standard;

b) test results;

c) features observed in the trials;

d) any operations not specified in this standard, or any additional operations that may affect the test results.

App YES (reference). Information about the compliance of the referenced international standards reference the national standards of the Russian Federation (and acting in this capacity inter-state standards)

App YES
(reference)

Table YES.1