GOST R ISO 4940-2010

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  ГОСТ Р ИСО 4940-2010

GOST R ISO 4940−2010 Steel and cast iron. Determination of Nickel. Spectrometric method of atomic absorption in the flame

GOST R ISO 4940−2010

Group B39

NATIONAL STANDARD OF THE RUSSIAN FEDERATION

STEEL AND CAST IRON

Determination of Nickel. Spectrometric method of atomic absorption in the flame

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

OKS 77.080.01
AXTU 0709

Date of introduction 2011−07−01

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 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 4

2 MADE by the Office of technical regulation and standardization of Federal Agency on technical regulation and Metrology

3 APPROVED AND put INTO EFFECT by the Federal Agency for technical regulation and Metrology of December 21, 2010 N 906-St

4 this standard is identical to international standard ISO 4940:1985* «Steel and cast iron. Determination of Nickel. Spectrometric method of atomic absorption in the flame» (ISO 4940:1985) «Steel and cast iron — Determination of nickel 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, details of which are given in Appendix YES

5 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 applies to steel and cast iron and sets spectrometric method of atomic absorption in the flame determine the Nickel content.

The method is applicable for determining the mass fraction of Nickel in the range from 0.002% to 0.5%.

2 Normative references

This standard uses the regulatory references to the following international standards*:
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* The table of conformity of national standards international see the link. — Note the manufacturer’s database.

ISO 377* Selection and preparation of samples and specimens for testing of wrought steel (ISO 377, Selection and preparation of samples and test pieces for wrought steel)
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* Valid ISO 14284:1996 Steel and iron. Selection and preparation of samples for chemical analysis.


ISO 5725* Precision of test methods. Determination of repeatability and reproducibility through round Robin test (ISO 5725, Precision of test methods — Determination of repeatability and reproducibility by inter-laboratory tests)
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* Valid ISO 5725−1:1994 Accuracy (trueness and precision) of methods and measurement results. Part 1. General principles and definitions.

3 the essence of the method

The method is based on dissolving the sample the sample in a mixture of the appropriate acids followed by evaporation to fumes of perchloric acid, the atomization of the solution in the flame of air-acetylene and spectrometric measurement of atomic absorption of radiation resonant with the 352.5 nm line emitted by the lamp with hollow cathode for Nickel.

Note — For some devices it is impossible to obtain sufficient sensitivity at the wavelength of the 352.5 nm for low concentrations of Nickel near the bottom of the field of measurements, in this case, you should use a wavelength 232,0 nm.


At the wavelength of the 352.5 nm signal-to-noise higher than at the wavelength of 232,0 nm. As a rule, the use of the 352.5 nm line gives the best reproducibility.

4 Reagents

In the analysis, except in cases otherwise specified, use only reagents of known analytical purity with a very low Nickel content and only distilled water or water of equivalent purity.

If possible, use only freshly prepared distilled or deionized water.

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

4.2 a Mixture of hydrochloric and nitric acids

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

Prepare this mixture immediately before use.

4.3 Mixture of nitric and perchloric acids

Mixed 100 cmof nitric acid (1,40 g/cm) 800 cmof perchloric acid (1.54 g/cm). Dilute with water to 1 DMand stirred.

Note — you Can use 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 Nickel, standard solution

4.4.1 stock solution of Nickel, 1 g/DM

Weighed with accuracy to 0.0001 g 0,5000 g of Nickel of high purity (purity of 99.9%) was dissolved in 25 cmof nitric acid (1.54 g/cm, diluted 1:1). Boil to remove nitric acid vapor. Cool and transfer the solution into volumetric flask with a capacity of 500 cmwith single-label, dilute to the mark with water and mix.

4.4.2 Standard solution of Nickel of 40 mg/DM

Placed 10.0 cmcore solution of Nickel (4.4.1) in a volumetric flask with one mark capacity of 250 cm, is diluted to the mark with water and mix.

1 cmof this standard solution contains 40 micrograms of Nickel.

Prepare standard solution immediately before use.

5 Instrument

Use ordinary laboratory apparatus.

5.1 Atomic absorption spectrometer

Lamp with hollow cathode for Nickel; supply of air and acetylene does not contain water, oil and Nickel and pure enough to ensure sustainable, transparent, lean fuel flame.

Atomic absorption spectrometer recognize the suitable to work, if after optimization of the measurement conditions on 7.3.4 the value of the detection limit and characteristic concentration are in accordance with the values given by the manufacturer of the device and on the same criteria of the accuracy given in 5.1.1.

5.1.1 the Minimum precision

Calculate the standard deviation of 10 measured values of absorbance of the most concentrated calibration solution. The standard deviation should not exceed 1.0% of the average value of absorption.

Calculate the standard deviation of the 10 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 of the most concentrated calibration solution.

It is recommended that the device meet tochnostyu the criteria set out in paragraphs 5.1.1.1. to 5.1.1.3.

5.1.1.1 Characteristic concentration

The characteristic concentration of Nickel in the matrix, such a finite subject solution sample the sample should be less than 0.50 mg/cmof Nickel to the wavelength of the 352.5 nm and less than 0.10 mg/cmNickel for wavelength 232,0 nm.

5.1.1.2 detection Limit

Detection limits calculated as twice the standard deviation of the 10 values of the absorption solution containing the corresponding element with the selected level of concentration giving absorbance slightly higher than the zero solution.

The detection limit of Nickel in the matrix, such a finite subject solution sample the sample should be less than 0.30 mg/cmof Nickel at a wavelength of the 352.5 nm and less than 0.15 mg/cmof Nickel at a wavelength of 232,0 nm.

5.1.1.3. the linearity of the graph

The slope of the calibration curve, expressed as the ratio of the magnitude of the absorption, corresponding to 20% range in the upper graph area to 20% concentration range in the lower chart area should not be less than 0.7.

For instruments with automatic calibration using two or more standard samples prior to analysis on the received indications of absorption to verify that the above requirements for the linearity of the calibration performed.

5.2 accessories

For the assessment criteria in 5.1.1 and for all subsequent measurements it is recommended to use the recorder with strip chart and/or digital reader.

The extension of the scale can be applied as long as the observed noise will not become more than error reader, and it is always recommended to use for the values of absorption less than 0.1.

If the extension of the scale should be used, and the device has no device for determining the expansion factor of the scale, this value can be calculate by simple division of the values of absorption measured for a suitable solution with the expansion of the scale, the value of absorption measured without expanding the scale.

6 Sampling

Sampling carried out in accordance with ISO 377.

7 analysis

Warning — Couple of perchloric acid can explode in the presence of ammonia, vapour of nitrous acid, or any organic materials.

The spray system and drainage system shall be cleaned of traces of perchloric acid after working with her.

Note — All glassware must first be washed with hydrochloric acid (of 1.19 g/cm, diluted 1:1) and then with water.


The amount of Nickel 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 Linkage of the sample

Weigh 1 g of the test sample to the nearest 0.001 g.

7.2 Control experience

In parallel with the definition of the same procedure carried out control experience, using the same quantities of all reagents, including iron (4.1)

7.3 Definition

7.3.1 Preparation of test solution

Place the weighed sample (7.1) in a beaker with a capacity of 250 cm. Add small portions of 15 cmmixture of nitric and perchloric acids (4.3), covered with a glass watch glass and gently warmed until the termination of the reaction of dissolution. Evaporate the solution until copious white fumes of perchloric acid. Continue the evaporation for 1 min at this temperature, to a pair of perchloric acid filled the entire volume of glass.

Note — the Samples that are poorly soluble in mixture of nitric and perchloric acids (4.3), is first dissolved in 10 cmof a mixture of hydrochloric and nitric acid (4.2), and then add 15 cmof a mixture of nitric and perchloric acid (4.3).


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

Filter the solution, decanter through dry filter paper to separate the sediment such as carbon, silicon dioxide or tungsten acid, and collect the filtrate in a dry beaker, rejecting the first portions.

If the Nickel content of the test sample in mass fraction exceeds 0.1%, the solution must be diluted in the following way: is placed 20.0 cmto the filtered solution in a volumetric flask with one mark capacity of 100 cm, is diluted to the mark and mix.

Note — If test solution needs dilution, in the same way should be diluted and the solution in the reference experiment (7.2).

7.3.2 Preparation of the calibration solutions

Put (10±0,1) g of iron (4.1) into a glass with a capacity of 800 cm, add 100 cmof a mixture of hydrochloric and nitric acid (4.2) and heated until dissolved.

When the dissolution ends, add 150 cmof a mixture of nitric and perchloric acid (4.3) and evaporated until the appearance of dense white fumes of perchloric acid. Continue the evaporation for 1 min at this temperature to a thick pair of perchloric acid filled the entire volume of glass.

After cooling, add 100 cmof water and gently heated to dissolve the salts. Again cooled and transferred quantitatively into a measuring flask with one mark capacity of 250 cm. Dilute to the mark with water and mix.

7.3.2.1 When the mass fraction of Nickel less than 0.1%

Taken in seven volumetric flasks with a capacity of 100 cmeach 25,0 cmaliquoting solution of iron (7.3.2). In the flask from a pipette or burette, add respectively 0 (zero solution); 2,5; 5,0; 10,0; 15,0; 20,0 and 25,0 cmstandard solution of Nickel (4.4.2), dilute to the mark with water and mix.

7.3.2.2 When the mass fraction of Nickel from 0.1% to 0.5%

Taken in seven volumetric flasks with a capacity of 100 cmevery 5.0 cmaliquoting solution of iron (7.3.2). In the flask from a pipette or burette, add respectively 0 (zero solution); 2,5; 5,0; 10,0; 15,0; 20,0 and 25,0 cmstandard solution of Nickel (4.4.2), dilute to the mark with water and mix.

Note — 1 cmof a standard solution of Nickel (4.4.2) diluted to 100 cm, equivalent to 0.004% Nickel in the case 7.3.2.1 and 0.02% Nickel — in case 7.3.2.2.

7.3.3 parameters of the atomic absorption spectrometer are shown in table 1.


Table 1

In the absence of recommendations regarding the width of the gap (table 1), should be guided by the following rule:

for the resonance lines of Nickel the 352.5 nm — slit width from 0.2 to 0.4 nm;

for the resonance lines of Nickel 232,0 nm — slit width from 0.15 to 0.25 nm.

Note — Must follow manufacturer’s recommendations and pay special attention to the following technical security requirements:

to understand the explosiveness of acetylene when it is used;

to protect operator’s eyes from UV radiation through the filter;

— to clear the head of the burner from the soot formed by the salts of perchloric acid and purified. Bad burner can give flash;

— to ensure that the liquid trap was filled with water.

7.3.4 optimization of the mode of operation of atomic absorption spectrometer

You must follow the manufacturer’s instructions when preparing the appliance for use.

Once the lamp current, wavelength and the gas flow is adjusted and the burner is ignited, spray water until stable readings.

Set the amount of absorption at zero, zero spraying the solution (or 7.3.2.1 7.3.2.2).

Choose Temperirovannyiy or integration time in order to obtain a stable signal, sufficient to meet the requirements tochnostyu criteria (5.1.1).

Regulate the flame so that it is slightly depleted fuel, and the height of the burner was approximately 1 cm below the light path. Alternately spray the calibration solution and the most concentrated to zero by adjusting the gas flow and the burner position (horizontal, vertical, and angled) as long as the difference in the magnitude of absorption between these calibration solutions will not be maximum. Check that the spectrometer have been accurately placed on 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

Set the extension of the scale so that the most concentrated calibration solution was allowed deviation, which is close to full scale. Atomize the calibration solutions in ascending order, respectively, repeating the measurement until each of them will give a set precision, which indicates the stable operation of the device. Choose two of the calibration solution is the one having absorption, slightly lower than the test solution and the other a little higher. Spray these solutions first in ascending order and then in descending, spraying the test solution into the middle, and in each case measure the magnitude of absorption relative to water. Again spray a complete set of calibration solutions. It should be recognized that these methods cannot be taken for instruments with automatic calibration for only two calibration solutions. In this case, do not use these two «sandwich» solution for initial calibration, but need to perform alternately with the test solution.

Calibration solutions sprayed repeatedly during the measurement series. Clean the burner if the results show a reduction in accuracy caused by contamination of the burner.

Get the value of the absorbance of each calibration solution.

Get the value of the absorbance of the test solution and the average value of the absorption solution of the blank experience.

Translate the values of absorbance of test solution and blank solution experience in micrograms of Nickel per milliliter using a calibration curve (7.4).

7.4 Construction of calibration curve

It is necessary to prepare a new calibration curve for each series of measurements, for each region the expected Nickel content.

Before building the graph, determine the concentration (actual or apparent concentration) of the zero solution in the calibration series. Concentration they are applied on a schedule of values of the first three absorption of the calibration solutions and by extrapolating the curve to the x-axis. This value of concentration, expressed in micrograms of Nickel per milliliter, added to the concentration value of each calibration solution before application to the calibration graph.

Build a calibration graph of values of absorption of the calibration solutions from the Nickel content in micrograms per milliliter.

Compare the magnitude of the absorption of two «sandwich» of the calibration solutions with the schedule. If these two calibration values do not deviate from the schedule more than the allowable accuracy criteria, the readings of the test solutions are also valid.

8 Processing of results

8.1 Calculation method

The content of the mass fraction of Nickel , %, is determined by the following formula

, (1)

where is the concentration of Nickel in the test solution, determined from calibration curve, mg/ml;

 — Nickel concentration in solution in the reference experiment, µg/ml;

 — the dilution factor (7.3.1),

=1 for samples with the expected Nickel content of 0,1% (mass fraction) or less;

=5 for the samples with the alleged content of Nickel more than 0.1%;

 — the weight of the portion of the sample.

8.2 Accuracy

Planned testing of this method was performed 6−18 laboratories for six levels of Nickel content, each laboratory was doing 2 to 5 for definitions of each level. Another test was conducted 13−19 laboratories for the seven levels of Nickel content, each laboratory made two definitions of Nickel for each level.

The obtained results were processed statistically in accordance with ISO 5725.

The data obtained showed a logarithmic relationship between the Nickel content, repeatability (convergence) and reproducibility of the results, as shown in table 2. The calculations were carried out in 10 series results for Nickel content (mass fraction) from 0.003% to 0.95%, corresponding to the range from 0.002% to 0.5% of Nickel, determined by this method.


Table 2

The difference between two single results of determination obtained in the test material by the same contractor using the same equipment and performing the test within a short period of time, may exceed the value of the frequency of occurrence average of not more than one in 20 in the normal and proper execution of the method.

The difference between two single and independent results of determination obtained by two executors in different laboratories for identical test material, may exceed the value of reproducibility average of not more than one in 20 in the normal and proper execution of the method.

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) a description of 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

App YES
(reference)

Table YES.1