ISO/TS 13899-3:2005

Steel - Determination of Mo, Nb and W contents in alloyed steel - Inductively coupled plasma atomic emission spectrometric method - Part 3: Determination of W content

ISO/TS 13899-1:2005 specifies a method for the determination of tungsten content in steel by means of inductively coupled plasma atomic emission spectrometry.

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 3: Dosage du W

General Information

• Status: Published
• Publication Date: 03-Mar-2005
• ICS: 77.080.20 - Steels
• Technical Committee: ISO/TC 17/SC 1 - Methods of determination of chemical composition
• Drafting Committee: ISO/TC 17/SC 1 - Methods of determination of chemical composition
• Current Stage: 9093 - International Standard confirmed
• Start Date: 24-Aug-2023
• Completion Date: 13-Dec-2025

Overview

ISO/TS 13899-3:2005 specifies an analytical procedure for the determination of tungsten (W) content in alloyed steel using inductively coupled plasma atomic emission spectrometry (ICP‑AES / ICP‑OES). The method covers preparation, dissolution, instrument performance checks, matrix‑matched calibration and bracketing, and calculation of results. It is applicable to tungsten mass fractions from 0.1% to 20%.

Keywords: ISO/TS 13899-3:2005, tungsten determination, ICP‑AES, alloyed steel, W content, matrix matching, calibration.

Key topics and technical requirements

• Scope and range: Valid for W contents of 0.1–20% (mass fraction).
• Sample preparation: Dissolution in a mixture of hydrochloric, nitric and hydrofluoric acids, fuming with a phosphoric/perchloric acid mix, re‑dissolution, filtration and dilution to a defined volume. Test portion sizes depend on expected W content (e.g., 0.5 g for 0.1–5% W; 0.1 g for 5–20% W).
• Reagents and standards: Use analytical‑grade reagents and Grade 2 water (ISO 3696). A tungsten stock standard (1 000 mg/L) must be prepared from high‑purity tungsten (≥99.95%); pre‑prepared commercial tungsten standards from third parties are not permitted for this stock solution.
• ICP requirements: Nebulizer and spray system must be resistant to hydrofluoric acid. Either simultaneous or sequential spectrometers may be used; if a sequential instrument is used with an internal standard, the internal standard line must be measured simultaneously.
• Instrument performance criteria:
  • Spectral bandwidth (resolution) < 0.030 nm for chosen lines.
  • Short‑term precision: RSD ≤ 0.5% at high concentrations (100–1 000 × LOD); ≤ 5% at 10–100 × LOD.
  • Limit of Detection (LOD) and Limit of Quantification (LOQ): example values given for W - LOD 1 mg/L, LOQ 5 mg/L.
• Calibration strategy: Close matrix matching and bracketing of calibration solutions around the sample concentration to compensate for matrix and spectral interferences; may require preliminary semi‑quantitative analysis to know major matrix elements.
• Internal standard: Optional but recommended for ratioing intensities; must be absent from sample and free from spectral interference.

Applications and users

• Routine and certified quality control and compositional verification in steel production and processing.
• Metallurgical laboratories, materials testing labs, and inspection/acceptance testing for alloy specification compliance.
• Research and development where precise tungsten quantification in high‑alloy steels is required.
• Instrument vendors and method validation labs implementing ICP‑AES methods for steel analysis.

Related standards

• ISO/TS 13899‑1:2005 (Mo determination) and ISO/TS 13899‑2:2005 (Nb determination) - same series for Mo, Nb, W.
• ISO 14284 (sampling/preparation of steel samples)
• ISO 3696 (water for analytical use)
• ISO 648, ISO 1042 (lab glassware)
• ISO 5725 series (precision and accuracy of measurement methods)

This standard is essential when accurate, interference‑resilient measurement of tungsten in alloy steels is required using ICP‑AES with rigorous sample prep and matrix‑matched calibration.

Standards Content (Sample)

TECHNICAL ISO/TS
SPECIFICATION 13899-3
First edition
2005-02-15
Steel — Determination of Mo, Nb and W
contents in alloyed steel — Inductively
coupled plasma atomic emission
spectrometric method —
Part 3:
Determination of W 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 3: Dosage du W
Reference number
©
ISO 2005
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©  ISO 2005
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ii © ISO 2005 – All rights reserved

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
n
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) Additional information on the international collaborative trial . 10
Annex C (informative) Graphical representation of precision data. 12

Foreword
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(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
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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.
In other circumstances, particularly when there is an urgent market requirement for such documents, a
technical committee may decide to publish other types of normative document:
— an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical experts in
an ISO working group and is accepted for publication if it is approved by more than 50 % of the members
of the parent committee casting a vote;
— an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical
committee and is accepted for publication if it is approved by 2/3 of the members of the committee casting
a vote.
An ISO/PAS or ISO/TS is reviewed after three years in order to decide whether it will be confirmed for a
further three years, revised to become an International Standard, or withdrawn. If the ISO/PAS or ISO/TS is
confirmed, it is reviewed again after a further three years, at which time it must either be transformed into an
International Standard or be withdrawn.
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/TS 13899-3 was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 1, Methods of
determination of chemical composition.
ISO/TS 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

TECHNICAL SPECIFICATION ISO/TS 13899-3:2005(E)

Steel — Determination of Mo, Nb and W contents in alloyed
steel — Inductively coupled plasma atomic emission
spectrometric method —
Part 3:
Determination of W content
1 Scope
This Technical Specification specifies a method for the determination of tungsten content in steel by means of
inductively coupled plasma atomic emission spectrometry.
This method is applicable to tungsten contents between 0,1 % and 20 % (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 1042:1998, 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 inductively coupled plasma
(ICP) spectrometer and the intensity of the emitted light from the element is measured simultaneously with the
light emitted from the internal standard element.
The method uses a calibration based on close matrix matching of the calibration solutions to the sample and
close bracketing of the tungsten content around the approximate concentration of tungsten 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 content of all elements in the sample (to the
nearest %). To this end, it may be necessary to carry out a preliminary analysis of the sample by a
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 % (mass fraction), ρ approximately 1,14 g/ml
4.2 Hydrochloric acid, HCl, ρ approximately 1,19 g/ml
4.3 Nitric acid, HNO , ρ approximately 1,40 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,
 shall not be present in the sample, and
 shall 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 Tungsten stock standard solution, 1 000 mg/l
Weigh, to the nearest 0,001 g, 0,5 g of high purity tungsten [minimum 99,95 % (mass fraction)] and dissolve in
a mixture of 10 ml hydrofluoric acid (4.1) and 20 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 W.
It is not permitted to use pre-prepared tungsten standard solutions supplied by second parties.
4.9 Tungsten standard solution, 100 mg/l
Transfer, with a calibrated micropipette, 25 ml of the tungsten stock standard solution (4.8) into a calibrated
250 ml one-mark plastic volumetric flask. Add 5 ml of hydrofluoric acid (4.1) and 10 ml of nitric acid (4.3).
Dilute to the mark with water and mix. 1 ml of this solution contains 0,1 mg of W.
2 © ISO 2005 – All rights reserved

NOTE If calibrated micropipettes of suitable volume are not available it would be more advantageous to use more
concentrated standard solutions. These solutions must, however, be prepared for each series of analysis, in order to avoid
possible precipitation.
4.10 Standard solutions of interfering and matrix elements
Prepare standard solutions for each element of which more than 1 % (mass fraction) is contained in the test
sample. Use pure elements or oxides with tungsten contents less than 10 µg/g. Commercial certified standard
solutions can also be used if the tungsten 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
The plastic pipettes and flasks to be used shall be 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 polytetrafluoroethylene (PTFE) 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 of plastic materials with better wetting-characteristics than PTFE 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
investigates the line/lines available on its own equipment to find the most suitable one regarding sensitivity
and freedom from interferences.
In Table 1, how
...