ISO 16918-1:2009

INTERNATIONAL ISO
STANDARD 16918-1
First edition
2009-01-15
Steel and iron — Determination of nine
elements by the inductively coupled
plasma mass spectrometric method —
Part 1:
Determination of tin, antimony, cerium,
lead and bismuth
Acier et fer — Dosage de neuf éléments par spectrométrie de masse
avec plasma induit par haute fréquence —
Partie 1: Dosage de l'étain, de l'antimoine, du cérium, du plomb et du
bismuth
Reference number
©
ISO 2009
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©  ISO 2009
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ii © ISO 2009 – All rights reserved

Contents Page
Foreword .iv
1 Scope.1
2 Normative references.1
3 Principle.1
4 Reagents.2
5 Apparatus.4
6 Measurement specifications .5
6.1 Minimum precision (RSD).5
6.2 Limit of detection (LOD) and limit of quantification (LOQ) .5
7 Sampling.6
8 Washing.6
9 Procedure.6
9.1 Test portion.6
9.2 Blank test solution [blank sample solution].6
9.3 Preparation of the test solution .6
10 Standard solutions .8
10.1 Multi-element standard solutions of the elements Sn, Sb, Pb and Bi .8
10.2 Standard solutions of the element Ce.9
11 Preparation of internal standard solutions (“internal standards”) — Y, Rh and Lu.9
11.1 Preparation in polystyrene test tubes .9
11.2 Preparation in volumetric flasks.10
12 Calibration blank solution and calibration solutions .10
12.1 Preparation in volumetric flasks.10
12.2 Preparation in polystyrene test tubes .11
13 Conditioning of the ICP-MS instrument .14
14 ICP-MS measurements.14
15 Plotting of calibration graphs.14
16 Expression of results.15
16.1 Method of calculation.15
16.2 Precision.15
17 Test report.17
Annex A (informative) Additional information on the international co-operative tests.18
Annex B (informative) Interferences in the determination of elements Sn, Sb, Ce, Pb and Bi using
ICP- MS .28
Bibliography.29

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 16918-1 was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 1, Methods of
determination of chemical composition.
ISO 16918 consists of the following parts, under the general title Steel and iron — Determination of nine
elements by the inductively coupled plasma mass spectrometric method:
⎯ Part 1: Determination of tin, antimony, cerium, lead and bismuth
⎯ Part 2: Determination of boron, silver, indium and thallium

iv © ISO 2009 – All rights reserved

INTERNATIONAL STANDARD ISO 16918-1:2009(E)

Steel and iron — Determination of nine elements by the
inductively coupled plasma mass spectrometric method —
Part 1:
Determination of tin, antimony, cerium, lead and bismuth
1 Scope
This part of ISO 16918 specifies a method for analysing steel and iron for the trace element determinations of
Sn, Sb, Ce, Pb and Bi using inductively coupled plasma mass spectrometry (ICP-MS). The method is
applicable for trace elements in the mass fraction ranges (µg/g) as follows:
Sn: 5 µg/g to 200 µg/g; Sb: 1 µg/g to 200 µg/g; Ce: 10 µg/g to 1 000 µg/g; Pb: 0,5 µg/g to 100 µg/g; Bi: from
0,3 µg/g to 30 µg/g.
Interferences in the determination of trace elements using ICP-MS are listed in Annex B.
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, Laboratory glassware — Single-volume pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
ISO 14284, Steel and iron — Sampling and preparation of samples for the determination of chemical
composition
3 Principle
A test portion is dissolved in an acid-mixture of hydrochloric acid, nitric acid and hydrofluoric acid using either
a microwave-assisted system or a traditional hot plate.
Diluted wet-digested samples are introduced into an inductively coupled plasma mass spectrometer (ICP-MS),
via a peristaltic pump. Simultaneous measurements of the intensities of elements with atomic mass units of
concern (mass spectra) are carried out using ICP-MS techniques.
Calibration blank and calibration solutions are matrix-matched with the major elements of steel, and mineral
acids are used for wet-digestion.
Internal standards are used throughout in order to compensate for any instrument drift.
4 Reagents
During the analysis, unless other stated, use only reagents of high purity quality containing less than
0,000 1 % mass fraction of each element or equivalent purity. The % given below refers to % mass fraction.
4.1 Hydrochloric acid, 30 % HCl, ρ 1,15 g/ml or 38 %, ρ 1,19 g/ml.
4.2 Nitric acid, 70 % HNO , ρ 1,42 g/ml.
4.3 Hydrofluoric acid, 49 % HF, ρ 1,16 g/ml.
4.4 Nitric acid, 65 % HNO , ρ 1,40 g/ml.
4.5 Ultra-pure water, produced by a water purification system giving a resistivity of 18 MΩ/cm or higher.
4.6 Washing solution for ICP-MS.
In a 500 ml plastic bottle (e.g. polyethylene) pour about 400 ml of ultra-pure water (4.5), then add 15 ml
hydrochloric acid (4.1), 5 ml nitric acid (4.2) and 2,5 ml hydrofluoric acid (4.3) and make it up to volume with
ultra-pure water (4.5).
The quality of the acids can be checked prior to use by a mass spectrum scan with the ICPMS instrument. It is
recommended to use a solution of 300 µl HCl (4.1) + 100 µl HNO (4.2) + 50 µl HF (4.3) with about 3 ml ultra-
pure water (4.5) and make it up to a volume of 10 ml. If peaks of elements of concern are present, a new flask
of acid shall be used and a new check of the same elements shall be carried out.
4.7 10 % nitric acid solution, HNO diluted 1+9.
In a 100 ml volumetric flask pour about 70 ml of ultra-pure water (4.5), then add 10 ml concentrated HNO
(4.2), and dilute to volume with ultra-pure water (4.5).
4.8 NaOH solution, 7,5 mol/l, ρ 1,33 g/ml.
4.9 NaOH solution, 0,2 mol/l.
Dispense 2,7 ml of 7,5 mol/l NaOH (4.8) into a 100 ml volumetric flask, and dilute to volume with ultra-pure
water (4.5).
The solution shall be stored in a polyethylene bottle or similar.
4.10 Aqua regia (HCl+HNO = 3+1).
Prepare aqua regia in a 30 ml beaker (or similar) by dispensing 9 ml HCl (4.1) and 3 ml HNO (4.2) into the
beaker.
4.11 Diluted aqua regia solution, diluted 4+10.
Dispense 100 ml ultra-pure water (4.5) into a 150 ml flask. Then add 40 ml aqua regia (4.10) and mix. Do not
make the solution up to volume.
4.12 50 % nitric acid solution, HNO diluted 1+1.
In a 100 ml volumetric flask, pour about 30 ml of ultra-pure water (4.5), then add 50 ml concentrated HNO
(4.2) and dilute to volume with ultra-pure water (4.5).
4.13 Perchloric acid, 70 % HClO , ρ 1,68 g/ml.
2 © ISO 2009 – All rights reserved

4.14 50 % hydrochloric acid solution, HCl diluted 1+1.
In a 100 ml volumetric flask, pour about 30 ml of ultra-pure water (4.5), then add 50 ml concentrated HCl (4.1)
and dilute to volume with ultra-pure water (4.5).
4.15 Iron, high purity quality containing less than 0,000 1 % mass fraction of each element.
4.16 Standard stock solutions, corresponding to 1 000 mg element per litre.
4.16.1 Tin standard stock solution
Dissolve 100,0 mg of high purity tin metal (99,9 % mass fraction, minimum) in 3 ml HCl (4.1) and 1 ml HNO
(4.2) in a 250 ml beaker. Heat gently to complete dissolution, cool, transfer into a 100 ml volumetric flask,
make the solution up to volume with ultra-pure water (4.5) and mix well.
Store the tin standard stock solution in a polyethylene bottle.
4.16.2 Antimony standard stock solution
Dissolve 100,0 mg of high purity antimony metal (99,9 % mass fraction, minimum) in 3 ml HCl (4.1) and 1 ml
HNO (4.2) in a 250 ml beaker. Heat gently to complete dissolution, cool, transfer into a 100 ml volumetric
flask, make the solution up to volume with ultra-pure water (4.5) and mix well.
Store the antimony standard stock solution in a polyethylene bottle.
4.16.3 Cerium standard stock solution
Dissolve 288,5 mg of pure cerium(IV) sulfate, Ce(SO ) 4H O, in
...