Steel -- Determination of Mo, Nb and W contents in alloyed steel -- Inductively coupled plasma atomic emission spectrometric method

ISO 13899-2:2005 specifies a method for the determination of the niobium content in steel by means of inductively coupled plasma emission spectrometry. This method is applicable to niobium contents between 0,005 and 5 % (mass fraction).

Aciers -- Dosage du Mo, du Nb et du W dans les aciers alliés -- Méthode par spectrométrie d'émission atomique avec plasma induit par haute fréquence

General Information

Status
Published
Publication Date
22-Jun-2005
Current Stage
6060 - International Standard published
Start Date
11-May-2005
Completion Date
23-Jun-2005
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ISO 13899-2:2005 - Steel -- Determination of Mo, Nb and W contents in alloyed steel -- Inductively coupled plasma atomic emission spectrometric method
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INTERNATIONAL ISO
STANDARD 13899-2
First edition
2005-06-15
Steel — Determination of Mo, Nb and W
contents in alloyed steel — Inductively
coupled plasma atomic emission
spectrometric method —
Part 2:
Determination of Nb content
Aciers — Dosage du Mo, du Nb et du W dans les aciers alliés —
Méthode par spectrométrie d'émission atomique avec plasma induit par
haute fréquence —
Partie 2: Dosage du Nb
Reference number
ISO 13899-2:2005(E)
ISO 2005
---------------------- Page: 1 ----------------------
ISO 13899-2:2005(E)
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© ISO 2005

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ii © ISO 2005 – All rights reserved
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ISO 13899-2:2005(E)
Contents Page

Foreword............................................................................................................................................................ iv

1 Scope ..................................................................................................................................................... 1

2 Normative references ........................................................................................................................... 1

3 Principle................................................................................................................................................. 1

4 Reagents................................................................................................................................................ 2

5 Apparatus .............................................................................................................................................. 3

6 Sampling and samples......................................................................................................................... 4

7 Procedure .............................................................................................................................................. 4

7.1 Preparation of test solution, T ........................................................................................................... 4

7.2 Preparation for spectrometric measurements................................................................................... 5

7.3 Pre-analysis of the test solution ......................................................................................................... 5

7.4 Preparation of calibration solutions for bracketing, K and K ................................................... 6

Ln Hn

7.5 Analysis of test solutions .................................................................................................................... 6

8 Expression of results ........................................................................................................................... 6

8.1 Method of calculation........................................................................................................................... 6

8.2 Precision................................................................................................................................................ 6

9 Test report ............................................................................................................................................. 7

Annex A (normative) Procedure for the determination of instrumental criteria.......................................... 8

Annex B (informative) Suggested lines together with possible spectral interferences in the

determination of Nb in steel by ICP-AES.......................................................................................... 10

Annex C (informative) Additional information on the international cooperative tests ............................. 11

Annex D (informative) Graphical representation of precision data ............................................................ 13

© ISO 2005 – All rights reserved iii
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ISO 13899-2:2005(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies

(ISO member bodies). The work of preparing International Standards is normally carried out through ISO

technical committees. Each member body interested in a subject for which a technical committee has been

established has the right to be represented on that committee. International organizations, governmental and

non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the

International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 13899-2 was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 1, Methods of

determination of chemical composition.

ISO 13899 consists of the following parts, under the general title Steel — Determination of Mo, Nb and W

contents in alloyed steel — Inductively coupled plasma atomic emission spectrometric method:

 Part 1: Detemination of Mo content
 Part 2: Detemination of Nb content
 Part 3: Detemination of W content
iv © ISO 2005 – All rights reserved
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INTERNATIONAL STANDARD ISO 13899-2:2005(E)
Steel — Determination of Mo, Nb and W contents in alloyed
steel — Inductively coupled plasma atomic emission
spectrometric method —
Part 2:
Determination of Nb content
1 Scope

This International Standard specifies a method for the determination of the niobium content in steel by means

of inductively coupled plasma emission spectrometry.

This method is applicable to niobium contents between 0,005 and 5 % (mass fraction).

2 Normative references

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced

document (including any amendments) applies.
ISO 648:1977, Laboratory glassware — One mark pipettes
ISO 1042:1983, Laboratory glassware — One mark volumetric flasks

ISO 3696:1987, Water for analytical laboratory use — Specification and test methods

ISO 5725-1:1994, Accuracy (trueness and precision) of measurement methods and results — Part 1: General

principles and definitions

ISO 5725-2:1994, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic

method for the determination of repeatability and reproducibility of a standard measurement method

ISO 5725-3:1994, Accuracy (trueness and precision) of measurement methods and results — Part 3:

Intermediate measures of the precision of a standard measurement method

ISO 14284:1996, Steel and iron — Sampling and preparation of samples for the determination of chemical

composition
3 Principle

The sample is dissolved in a hydrochloric, nitric and hydrofluoric acid mixture and fumed with a phosphoric

and perchloric acid mixture. Hydrofluoric acid and an internal standard element (if used) are added and the

solution is diluted to known volume. The solution is filtered and nebulized into an ICP and the intensity of the

emitted light from each element is measured simultaneously with the light emitted from the internal standard

element.
© ISO 2005 – All rights reserved 1
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ISO 13899-2:2005(E)

The method uses a calibration based on close matrix matching of the calibration solutions to the sample and

close bracketing of the niobium content around the approximate concentration of niobium in the sample to be

analysed. This compensates for matrix interferences and provides high accuracy, even in highly alloyed steels

where spectral interferences can be severe. Nonetheless, all interferences shall be kept to a minimum and it is

therefore essential that the spectrometer used meets the performance criteria specified in the method for the

selected analytical lines.

In order to accurately matrix match, it is necessary to know the concentration of all elements in the sample (to

the nearest percent). To this end, it may be necessary to carry out a preliminary analysis of the sample by

some semi-quantitative method.
4 Reagents

During the analysis, unless otherwise stated, use only reagents of recognised analytical grade and only

grade 2 water, as specified in ISO 3696.
4.1 Hydrofluoric acid, HF, 40 % (m/m), ρ approximately 1,14 g/ml.
4.2 Hydrochloric acid, HCl, ρ approximately 1,19 g/ml.
4.3 Nitric acid, HNO , ρ approximately 40 g/ml.
4.4 Phosphoric acid, H PO , ρ approximately 1,70 g/ml, diluted 1 + 1.
3 4
4.5 Perchloric acid, HClO , ρ approximately 1,54 g/ml, diluted 1 + 1.

4.6 Fuming acid mixture, mix 100 ml of the phosphoric acid (4.4) and 300 ml of the perchloric acid (4.5).

4.7 Internal standard solution, 1 000 mg/l.

Choose a suitable element to be added as internal standard and prepare a 1 000 mg/l solution. The internal

standard chosen shall
 be pure,
 not be present in the sample, and

 not interfere with analytical wavelengths, nor should the internal standard element wavelength be

interfered with by elements in the test solution.

The internal standard shall be soluble in the acids used and it shall not cause precipitation. Moreover, the

excitation conditions of the analytical line and the internal standard element line should match.

4.8 Niobium stock standard solution, 1 000 mg/l.

Weigh, to the nearest 0,000 1 g, 0,5 g of high purity niobium [min 99,95 % (mass fraction)] and dissolve in a

mixture of 30 ml hydrofluoric acid (4.1) and 3 ml nitric acid (4.3). Cool and transfer the solution quantitatively

to a calibrated 500 ml one-mark plastic volumetric flask. Dilute to the mark with water and mix. 1 ml of this

solution contains 1 mg of Nb.

NOTE It is not permitted to use pre-prepared niobium standard solutions supplied by second parties.

4.9 Niobium standard solution, 100 mg/l.

Transfer, with a calibrated pipette, 25 ml of the niobium stock standard solution (4.8) into a calibrated 250 ml

one-mark plastic volumetric flask. Add 2,5 ml of hydrofluoric acid (4.1). Dilute to the mark with water and mix.

1 ml of this solution contains 0,1 mg of Nb.
2 © ISO 2005 – All rights reserved
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ISO 13899-2:2005(E)
4.10 Niobium standard solution, 10 mg/l.

Transfer, with a calibrated pipette, 2,5 ml of the niobium stock standard solution (4.8) into a calibrated 250 ml

one-mark plastic volumetric flask. Add 2,5 ml of hydrofluoric acid (4.1). Dilute to the mark with water and mix.

1 ml of this solution contains 0,01 mg of Nb.
4.11 Standard solutions of interfering and matrix elements.

Prepare standard solutions for each element above 1 % (mass fraction) in the test sample. Use pure elements

or oxides with niobium contents less than 10 µg/g (mass fraction). Commercial certified standard solutions can

also be used if the niobium content is less than the value specified above.

NOTE If a large amount of an element is to be added (e.g. iron), it might be more advantageous to use the pure

metal and weigh the correct amount (see 7.3 and 7.4). In this case, use the dissolution procedure described in 7.1.2.

5 Apparatus

As it, for obvious reasons, is impossible to use volumetric glassware in this application, the laboratory has to

make sure that the plastic pipettes and flasks to be used are calibrated in accordance with ISO 648 or

ISO 1042 as appropriate.
Ordinary laboratory apparatus and

5.1 Atomic emission spectrometer, equipped with an inductively coupled plasma (ICP) and a

nebulization system resistant to hydrofluoric acid.

When a teflon nebulizer is used, it is recommended that a surface active agent should be added to improve

wetting in the nebulizer and spray chamber. Modern nebulizers are, however, often manufactured in plastic

materials with better wetting-characteristics than Teflon and can therefore (as is the case with sapphire

nebulizers) be used without a surface active agent.

The ICP-ES spectrometer used will be satisfactory if, after optimising according to 7.2.1 to 7.2.4, it meets the

performance criteria given in 5.1.2 to 5.1.4.

The spectrometer can be either the simultaneous or the sequential type. A sequential type can be used either

with or without an internal standard. However, if a sequential spectrometer is to be used with an internal

standard, it shall be fitted with an arrangement which allows for the simultaneous measurement of the internal

standard line.
5.1.1 Analytical lines

This standard does not specify any particular emission line. It is mandatory that each laboratory carefully

investigate the line/lines available on its own equipment to find the most suitable one regarding sensitivity and

freedom from interferences.

In Table 1, however, two suggestions are given together with possible interferences. These lines have been

carefully investigated (see Annex B).

The line for the internal standard element should be selected according to 4.7. It is, however, recommended to

use Sc 363.07 nm. This line is interference free for the elements and concentrations given in Annex B.

Table 1 — Examples of analytical lines together with interfering elements
Wavelength
Possible
Element
interferences
Nb 309,41 V, Cr, Ni
Nb 316,34 Fe, Cr, V, W, Ti
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ISO 13899-2:2005(E)
5.1.2 Minimum practical resolution of the spectrometer

Calculate the bandwidth, according to Clause A.1, for the wavelength used including the line for the internal

standard. The bandwidth shall be less than 0,030 nm.
5.1.3 Minimum short-term precision

Calculate the short-term precision according to Clause A.2. The relative standard deviation shall not exceed

0,5 % of the mean absolute or ratioed intensities for concentrations 100 to 1 000 times the LOD (6.1.4) mg/l.

For concentrations 10 to 100 times the
...

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