ISO 13933:2014
(Main)Steel and iron — Determination of calcium and magnesium — Inductively coupled plasma atomic emission spectrometric method
Steel and iron — Determination of calcium and magnesium — Inductively coupled plasma atomic emission spectrometric method
ISO 13933:2014 specifies a method for determination of calcium and magnesium contents in iron, cast iron, steel, and alloyed steel by inductively coupled plasma (ICP) atomic emission spectrometry. The method is applicable to the determination of calcium and magnesium contents (mass fraction) in the range of 0,000 5 % to 0,006 % and 0,000 5 % to 0,20 %, respectively.
Aciers et fontes - Détermination du calcium et du magnésium - Méthode par spectrométrie d'émission atomique avec plasma induit
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INTERNATIONAL ISO
STANDARD 13933
First edition
2014-07-15
Steel and iron — Determination of
calcium and magnesium — Inductively
coupled plasma atomic emission
spectrometric method
Aciers et fontes - Détermination du calcium et du magnésium -
Méthode par spectrométrie d’émission atomique avec plasma induit
Reference number
ISO 13933:2014(E)
©
ISO 2014
---------------------- Page: 1 ----------------------
ISO 13933:2014(E)
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© ISO 2014
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
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Published in Switzerland
ii © ISO 2014 – All rights reserved
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ISO 13933:2014(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Principle . 1
4 Reagents . 1
5 Apparatus . 3
5.1 Inductively coupled plasma atomic emission spectrometer . 3
5.2 Polytetrafluoroethylene (PTFE) beakers with PTFE cover . 4
6 Sampling . 5
7 Procedure. 5
7.1 Test portion . 5
7.2 Blank test . 5
7.3 Determination . 5
7.4 Adjustment of the apparatus . 7
7.5 Measurement of the calibration solutions . 7
7.6 Plotting a calibration curve . 8
7.7 Measurements of the test solution . 8
8 Expression of results . 8
8.1 Method of calculation . 8
8.2 Precision . 8
9 Test report . 9
Annex A (normative) Procedure for the determination of instrumental criteria .10
Annex B (informative) Additional information on international cooperative test .12
Annex C (informative) Graphical representation of precision data .14
Bibliography .16
© ISO 2014 – All rights reserved iii
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ISO 13933:2014(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 17, Steel, Subcommittee SC 1, Methods of
determination of chemical composition.
iv © ISO 2014 – All rights reserved
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INTERNATIONAL STANDARD ISO 13933:2014(E)
Steel and iron — Determination of calcium and
magnesium — Inductively coupled plasma atomic emission
spectrometric method
1 Scope
This International Standard specifies a method for determination of calcium and magnesium contents in
iron, cast iron, steel, and alloyed steel by inductively coupled plasma (ICP) atomic emission spectrometry.
The method is applicable to the determination of calcium and magnesium contents (mass fraction) in
the range of 0,000 5 % to 0,006 % and 0,000 5 % to 0,20 %, respectively.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 385, Laboratory glassware — Burettes
ISO 648, Laboratory glassware — Single-volume pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 14284, Steel and iron — Sampling and preparation of samples for the determination of chemical
composition
3 Principle
A test portion is dissolved in a hydrochloric, nitric and hydrofluoric acid mixture and fumed with
perchloric acid. Hydrochloric acid, nitric acid, and an internal standard element (if used) are added and
the solution is diluted to a known volume. The solution is filtered if necessary, nebulized into an ICP
spectrometer and the intensity of the emitted light from each element measured simultaneously with
the intensity of the light emitted by the internal standard element.
4 Reagents
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade with very
low calcium and magnesium contents and only grade 2 water as specified in ISO 3696.
4.1 Pure iron, containing less than 0,5 μg/g of calcium and magnesium.
4.2 Hydrochloric acid, ρ about 1,19 g/ml.
4.3 Hydrochloric acid, ρ about 1,19 g/ml, diluted 1 + 1.
4.4 Hydrochloric acid, ρ about 1,19 g/ml, diluted 1 + 4.
4.5 Hydrochloric acid, ρ about 1,19 g/ml, diluted 1 + 100.
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ISO 13933:2014(E)
4.6 Nitric acid, ρ about 1,42 g/ml.
4.7 Hydrofluoric acid, ρ about 1,14 g/ml.
4.8 Perchloric acid, ρ about 1,67 g/ml.
4.9 Acid mixture.
Mix two volumes of hydrochloric acid (4.2), one volume of nitric acid (4.6), and three volumes of water.
4.10 Calcium standard solutions.
4.10.1 Calcium stock solution, corresponding to 1 000 mg of calcium per litre.
Dry several grams of calcium carbonate [purity ≥99,9 % (mass fraction)] in an oven at 100 °C ± 5 °C
for at least 1 h and cool to room temperature in a desiccator. Weigh, to the nearest 0,000 1 g, 2,497 g of
the dried product into a 400 ml beaker, add 20 ml of hydrochloric acid (4.3), cover with a watch-glass
and heat gently until the product is completely dissolved. Cool to room temperature and transfer the
solution into a 1 000 ml one-mark volumetric flask. Dilute to the mark with water and mix.
1 ml of this stock solution contains 1,000 mg of calcium.
4.10.2 Calcium standard solution A, corresponding to 100 mg of calcium per litre.
Transfer 10,00 ml of calcium stock solution (4.10.1) into a 100 ml one-mark volumetric flask. Add 10 ml
of hydrochloric acid (4.4). Dilute to the mark with water and mix.
1 ml of this standard solution contains 0,100 mg of calcium.
4.10.3 Calcium standard solution B, corresponding to 10 mg of calcium per litre.
Transfer 10,00 ml of calcium standard solution A (4.10.2) into a 100 ml one-mark volumetric flask. Add
10 ml of hydrochloric acid (4.4). Dilute to the mark with water and mix.
1 ml of this standard solution contains 0,010 mg of calcium.
4.10.4 Calcium standard solution C, corresponding to 1,0 mg of calcium per litre.
Transfer 10,00 ml of calcium standard solution B (4.10.3) into a 100 ml one-mark volumetric flask. Add
10 ml of hydrochloric acid (4.4). Dilute to the mark with water and mix.
1 ml of this standard solution contains 0,001 mg of calcium.
4.11 Magnesium standard solutions
4.11.1 Magnesium stock solution, corresponding to 1 000 mg of magnesium per litre.
Weigh, to the nearest 0,000 1 g, 1,000 g of pure magnesium [purity ≥99,9 % (mass fraction)] and transfer
into a 250 ml beaker. Add 20 ml of water, then add hydrochloric acid (4.3) drop by drop while swirling
until the acid action ceases and continue adding hydrochloric acid (4.3) to a total volume of 20 ml. Cover
with a watch-glass and heat to boil for 10 min. After cooling, transfer the solution quantitatively into a
1 000 ml one-mark volumetric flask. Dilute to the mark with water and mix.
1 ml of this stock solution contains 1,000 mg of magnesium.
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ISO 13933:2014(E)
4.11.2 Magnesium standard solution A, corresponding to 100 mg of magnesium per litre.
Transfer 10,00 ml of magnesium stock solution (4.11.1) into a 100 ml one-mark volumetric flask. Add
10 ml of hydrochloric acid (4.4). Dilute to the mark with water and mix.
1 ml of this standard solution contains 0,100 mg of magnesium.
4.11.3 Magnesium standard solution B, corresponding to 10 mg of magnesium per litre.
Transfer 10,00 ml of magnesium standard solution A (4.11.2) into a 100 ml one-mark volumetric flask.
Add 10 ml of hydrochloric acid (4.4). Dilute to the mark with water and mix.
1 ml of this standard solution contains 0,010 mg of magnesium.
4.11.4 Magnesium standard solution C, corresponding to 1,0 mg of magnesium per litre.
Transfer 10,00 ml of magnesium standard solution B (4.11.3) into a 100 ml one-mark volumetric flask.
Add 10 ml of hydrochloric acid (4.4). Dilute to the mark with water and mix.
1 ml of this standard solution contains 0,001 mg of magnesium.
4.12 Yttrium internal standard solution, corresponding to 100 mg of yttrium per litre.
Calcine several grams of yttrium oxide [purity ≥99,9 % (mass fraction)] in a muffle furnace at
850 °C ± 10 °C for at least 40 min and then cool to room temperature in a desiccator. Weigh 0,127 0 g of
the calcined product into a 400 ml beaker, add 10 ml of hydrochloric acid (4.3), cover with a watch-glass,
and heat gently until the product is completely dissolved. Cool to room temperature and transfer the
solution to a 1 000 ml one-mark volumetric flask. Dilute to the mark with water and mix.
1 ml of this standard solution contains 0,100 mg of yttrium.
5 Apparatus
All volumetric glassware shall be class A and calibrated in accordance with ISO 385, ISO 648, or ISO 1042,
as appropriate.
Ordinary laboratory apparatus and the following shall be used.
5.1 Inductively coupled plasma atomic emission spectrometer
The inductively coupled plasma atomic emission spectrometer used will be satisfactory if, after
optimizing according to 7.4, it meets the performance criteria given in 5.1.2 to 5.1.4.
The spectrometer can be either a simultaneous or a sequential one. If a sequential spectrometer can be
equipped with an extra arrangement for simultaneous measurement of the internal standard line, it can
be used with the internal standard technique. If the sequential spectrometer is not equipped with this
arrangement, the internal standard cannot be used and an alternative technique without an internal
standard shall be applied.
5.1.1 Analytical wavelengths
This method does not specify any particular emission line. It is mandatory that each laboratory carefully
investigates the wavelengths available on its own equipment to find the most suitable one regarding
sensitivity and absence of interferences.
In Table 1, however, several suggestions are given together with possible interferences. These
wavelengths have been carefully investigated
© ISO 2014 – All rights reserved 3
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ISO 13933:2014(E)
The wavelength of the internal standard element chosen shall not interfere with the analytical
wavelengths, nor should the internal element wavelength be interfered by elements present in the test
solution. It is, however, recommended to use Y 371,03 nm or Y 360,07 nm. This wavelength is free of
interferences from the elements.
Table 1 — Analytical wavelengths together with interfering elements
Wavelength
Element Possible interferences
nm
Ca 393,66 none
Mg 279,55 none
371,03 none
Y
360,07 none
Other elements can be used as internal standards, but they shall not be present in the sample, and
shall not interfere with the elements to be determined at the appropriate wavelengths. Likewise, the
elements present in the test solution shall not interfere with the internal standard at the wavelength
chosen. The excitation requirements of the internal standard should be similar to those of the elements
to be determined.
5.1.2 Minimum practical resolution of the spectrometer
Calculate the bandwidth, according to A.1, for the wavelength used. The bandwidth shall be less than
0,030 nm.
5.1.3 Minimum short-term precision
Calculate the short-term precision according to A.2. The relative standard deviation (RSD) shall not
exceed 1 % of the mean absolute or ratioed intensities for concentrations 100 to 1 000 times the limit
of detection (LOD) (5.1.4). For concentrations that are 10 to 100 times the LOD (5.1.4), the RSD shall not
exceed 5 %.
5.1.4 Limit of Detection (LOD) and Limit of Quantification (LOQ)
Calculate the LOD and LOQ, according to A.3, for the analytical wavelengths used. The calculated values
shall be below the values given in Table 2.
Table 2 — Limit of Detection (LOD) and Limit of Quantification (LOQ)
Wavelength LOD LOQ
Element
nm mg/l mg/l
Ca 393,66 0,003 4 0,010
Mg 279,55 0,004 6 0,014
5.1.5 Linearity of the calibration curve
The linearity of the calibration curve is checked by calculating the correlation coefficient. This coefficient
shall be higher than 0,999.
5.2 Polytetrafluoroethylene (PTFE) beakers with PTFE cover
NOTE For the determination of magnesium, glass beakers and watch-glass covers can be used.
5.3 Volumetric flask, of capacity 100 ml, made of polypropylene or polyethylene terephthalate (PET).
4 © ISO 2014 – All rights reserved
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ISO 13933:2014(E)
5.4 Filter, 0,22 μm pore size, 47 mm diameter PTFE, or polycarbonate filter membrane.
5.5 Suction filtration system, including a flask, a filter funnel, and a vacuum filtration device.
6 Sampling
Sampling shall be carried out in accordance with ISO 14284 or with an appropriate national standard
for steels and cast irons.
7 Procedure
WARNING — Perchloric acid vapour can cause explosions in the presence of ammonia, nitrous
fumes, or organic matter in general.
All glassware and plasticware shall first be washed with hydrochloric acid (4.3), then with water. The
quantities of calcium and magnesium in the glassware and plasticware can be checked by measuring
the intensity of the emitted light of water poured into glassware and plasticware after washing with
acid and rinsing with water. If contamination from calcium and magnesium is present, the glassware
and plasticware are unsuitable and should be replaced or cleaned again.
For each set of determinations, all reagents, including water, calibration and test solutions, shall be from
the same batch.
7.1 Test portion
Place the sample or the pure iron in a PTFE beaker. Add 10 ml of hydrochloric acid (4.5) and swirl the
beaker gently. Discard the hydrochloric acid s
...
DRAFT INTERNATIONAL STANDARD ISO/DIS 13933
ISO/TC 17/SC 1 Secretariat: JISC
Voting begins on Voting terminates on
2012-08-28 2013-01-28
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ ORGANISATION INTERNATIONALE DE NORMALISATION
Steel and iron — Determination of calcium and magnesium —
Inductively coupled plasma atomic emisson spectrometric
method
Aciers et fontes — Détermination du calcium et du magnésium — Méthode spcectrométrique d'émission
atomique avec plasma induit
ICS 77.080.01
To expedite distribution, this document is circulated as received from the committee
secretariat. ISO Central Secretariat work of editing and text composition will be undertaken at
publication stage.
Pour accélérer la distribution, le présent document est distribué tel qu'il est parvenu du
secrétariat du comité. Le travail de rédaction et de composition de texte sera effectué au
Secrétariat central de l'ISO au stade de publication.
THIS DOCUMENT IS A DRAFT CIRCULATED FOR COMMENT AND APPROVAL. IT IS THEREFORE SUBJECT TO CHANGE AND MAY NOT BE
REFERRED TO AS AN INTERNATIONAL STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS BEING ACCEPTABLE FOR INDUSTRIAL, TECHNOLOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON OCCASION HAVE TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL TO BECOME
STANDARDS TO WHICH REFERENCE MAY BE MADE IN NATIONAL REGULATIONS.
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT, WITH THEIR COMMENTS, NOTIFICATION OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPORTING DOCUMENTATION.
© International Organization for Standardization, 2012
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ISO/DIS 13933
Copyright notice
This ISO document is a Draft International Standard and is copyright-protected by ISO. Except as permitted
under the applicable laws of the user’s country, neither this ISO draft nor any extract from it may be
reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic,
photocopying, recording or otherwise, without prior written permission being secured.
Requests for permission to reproduce should be addressed to either ISO at the address below or ISO’s
member body in the country of the requester.
ISO copyright office
Case postale 56 CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Reproduction may be subject to royalty payments or a licensing agreement.
Violators may be prosecuted.
ii © ISO 2012 – All rights reserved
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ISO/DIS 13933
Contents Page
Foreword . iv
1 Scope . 1
2 Normative references . 1
3 Principle . 1
4 Reagents . 1
5 Apparatus . 3
6 Sampling . 5
7 Procedure . 5
7.1 Test portion . 5
7.2 Blank test . 6
7.3 Determination . 6
7.4 Preparation for spectrometric measurements . 8
7.5 Measurement of the calibration solutions . 8
7.6 Plotting of calibration curve . 8
7.7 Measurements of the test solution . 8
8 Expression of results . 9
8.1 Method of calculation . 9
8.2 Precision . 9
9 Test report . 10
Annex A (normative) Procedure for the determination of instrumental criteria . 11
Annex B (informative) Additional information on international cooperative tests . 13
Annex C (informative) Graphical representation of precision data . 15
Bibliography . 17
© ISO 2012 – All rights reserved iii
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ISO/DIS 13933
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 13933 was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 1, Methods of
determination of chemical composition.
iv © ISO 2012 – All rights reserved
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DRAFT INTERNATIONAL STANDARD ISO/DIS 13933
Steel and iron — Determination of calcium and magnesium —
Inductively coupled plasma atomic emission spectrometric
method
1 Scope
This draft specifies a method for determination of calcium and magnesium contents in iron, cast iron, steel and
alloyed steel by inductively coupled plasma atomic emission spectrometry.
The method is applicable to the determination of calcium and magnesium in content range (mass fraction) from
0,000 5 % to 0.006 % and from 0,000 5 % to 0,20 %, respectively.
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 385, Laboratory glassware – Burettes
ISO 648, Laboratory glassware -- Single-volume pipettes
ISO 1042, Laboratory glassware – One mark volumetric flasks
ISO 3696, Water for analytical laboratory use – Specification and test methods
ISO 14284, Steel and iron -- Sampling and preparation of samples for the determination of chemical composition
3 Principle
A test portion is dissolved in hydrochloric, nitric and hydrofluoric acid mixture and fumed with perchloric acid.
Hydrochloric acid and an internal standard element (if used) are added and the solution is diluted to a known
volume. The solution is filtered, if necessary, and nebulized into an ICP and the intensity of the emitted light from
each element is measured simultaneously with the intensity of the light emitted by the internal standard element.
Iron is used as matrix in the calibration solution, the quantities of iron being the same as that of the test portion.
4 Reagents
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade having very low
calcium and magnesium contents and only grade 2 water as specified in ISO 3696.
© ISO 2012 – All rights reserved 1
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ISO/DIS 13933
4.1 Pure iron, containing less than 0,000 1 % (mass fraction) of calcium and magnesium.
4.2 Hydrochloric acid, ρ about 1,19 g/ml.
4.3 Hydrochloric acid, ρ about 1,19 g/ml, diluted 1+1
4.4 Hydrochloric acid, ρ about 1,19 g/ml, diluted 1+4.
4.5 Nitric acid, ρ about 1,42 g/ml.
4.6 Hydrofluoric acid, ρ about 1,14 g/ml.
4.7 Perchloric acid, ρ about 1,67 g/ml.
4.8 Acid mixture
Mix two volumes of hydrochloric acid (4.2), one volume of nitric acid (4.5) and three volumes of water.
4.9 Calcium standard solution
4.9.1 Calcium stock solution, corresponding to 1 000 mg of calcium per litre.
Dry several grams of calcium carbonate [purity ≥ 99,9 % (mass fraction)] in an oven at 100 ˚C ± 5 ˚C for at least
1 h and cool to room temperature in a desiccator. Weigh, to the nearest 0,0001 g, 2,497 g of the dried product into
a 400 ml beaker, add 20 ml of hydrochloric acid (4.3), cover with a watch-glass and heat gently until the product is
completely dissolved. Cool to room temperature and transfer the solution into a 1 000 ml one-mark volumetric flask,
dilute to the mark with water and mix.
1 ml of this stock solution contains 1,000 mg of calcium.
4.9.2 Calcium standard solution A, corresponding to 100 mg of calcium per litre.
Transfer, with a calibrated pipette, 10,00 ml of calcium stock solution (4.9.1) into a calibrated 100 ml one-mark
volumetric flask. Add 10 ml of hydrochloric acid (4.4). Dilute to the mark with water and mix.
1 ml of this standard solution contains 0,100 mg of calcium.
4.9.3 Calcium standard solution B, corresponding to 10 mg of calcium per litre.
Transfer, with a calibrated pipette, 10,00 ml of calcium standard solution A (4.9.2) into a calibrated 100 ml one-mark
volumetric flask. Add 10 ml of hydrochloric acid (4.4). Dilute to the mark with water and mix.
1 ml of this standard solution contains 0,010 mg of calcium.
4.9.4 Calcium standard solution C, corresponding to 1,0 mg of calcium per litre.
Transfer, with a calibrated pipette, 10,00 ml of calcium standard solution A (4.9.3) into a calibrated 100 ml one-mark
volumetric flask. Add 10 ml of hydrochloric acid (4.4). Dilute to the mark with water and mix.
1 ml of this standard solution contains 0,001 mg of calcium.
2 © ISO 2012 – All rights reserved
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ISO/DIS 13933
4.10 Magnesium standard solution
4.10.1 Magnesium stock solution, corresponding to 1 000 mg of magnesium per litre.
Weigh, to the nearest 0,000 1 g, 1,000 g of pure magnesium [purity ≥ 99,9 % (mass fraction)] and transfer into a
250 ml beaker. Add 20 ml of water, and add hydrochloric acid (4.3) drop by drop whilst swirling until the acid action
ceases, and continue adding hydrochloric acid (4.3) to 20 ml. Cover with a watch glass and heat to boil for 10 min.
After cooling, transfer the solution quantitatively into a 1 000 ml one-mark volumetric flask, dilute to the mark with
water and mix.
1 ml of this stock solution contains 1,000 mg of magnesium.
4.10.2 Magnesium standard solution A, corresponding to 100 mg of magnesium per litre.
Transfer, with a calibrated pipette, 10,00 ml of magnesium stock solution (4.10.1) into a calibrated 100 ml one-mark
volumetric flask. Add 10 ml of hydrochloric acid (4.4). Dilute to the mark with water and mix.
1 ml of this standard solution contains 0,100 mg of magnesium.
4.10.3 Magnesium standard solution B, corresponding to 10 mg of magnesium per litre.
Transfer, with a calibrated pipette, 10.00 ml of magnesium standard solution A (4.10.2) into a calibrated 100 ml one-
mark volumetric flask. Add 10 ml of hydrochloric acid (4.4). Dilute to the mark with water and mix.
1 ml of this standard solution contains 0,010 mg of magnesium.
4.10.4 Magnesium standard solution C, corresponding to 1,0 mg of magnesium per litre.
Transfer, with a calibrated pipette, 10,00 ml of magnesium standard solution A (4.10.3) into a calibrated 100 ml one-
mark volumetric flask. Add 10 ml of hydrochloric acid (4.4). Dilute to the mark with water and mix.
1 ml of this standard solution contains 0,001 mg of magnesium.
4.11 Yttrium internal standard solution, corresponding to 100 mg of yttrium per litre.
Calcine several grams of yttrium oxide [purity ≥ 99,9 % (mass fraction)] in a muffle furnace at 850 ˚C ± 10 ˚C for at
least 40 min and then cool to room temperature in a desiccator. Weigh 0,127 0 g of the calcined product into a 400
ml beaker, add 10 ml of hydrochloric acid (4.3), cover with a watch-glass, and heat gently until the product is
completely dissolved. Cool to room temperature and transfer the solution to a 1 000 ml one-mark volumetric flask,
dilute to the mark with water and mix.
1 ml of this stock solution contains 0,100 mg of yttrium.
5 Apparatus
All volumetric glassware shall be class A, in accordance with ISO 385, ISO 648 or ISO 1042 as appropriate.
Ordinary laboratory apparatus and
5.1 Inductively coupled plasma atomic emission spectrometer
The inductively coupled plasma atomic emission spectrometer used will be satisfactory if, after optimizing according
to 7.4, it meets the performance criteria given in 5.1.2 to 5.1.4.
© ISO 2012 – All rights reserved 3
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ISO/DIS 13933
The spectrometer can be either the simultaneous or the sequential type. If a sequential spectrometer can be
equipped with an extra arrangement for simultaneous measurement of the internal standard line, it can be used with
the internal standard technique. If the sequential spectrometer is not equipped with this arrangement, the internal
standard can not be used and an alternative technique without internal standard shall be applied.
5.1.1 Analytical lines
This method does not specify any particular emission line. It is mandatory that each laboratory carefully investigate
the lines available on its own equipment to find the most suitable one regarding sensitivity and absence of
interferences.
In Table 1, however, several suggestions are given together with possible interferences. These lines have been
carefully investigated (see Annex B).
The line of the internal standard element chosen shall not interfere with the analytical wavelengths, nor should the
internal element wavelength be interfered by elements present in the test solution. It is, however, recommended to
use Y 371,03 nm. This line is free of interferences from the elements given in Annex B.
Table 1 — Analytical lines together with interfering elements
Wavelength
Element Possible Interferences
nm
Ca 393,66 none
Mg 279,55 none
371,03 none
Y
360,0 none
NOTE Other element can be used as internal standard, but it shall not be present in the sample, and shall not interfere with
the analytical wavelengths, nor should elements present in the test solution interfere with the internal element wavelength. The
exciting conditions of the internal standard element shall be similar to that of the analytical elements.
5.1.2 Minimum practical resolution of the spectrometer
Calculate the bandwidth, according to the Annex A, Clause A.1, for the wavelength used. The bandwidth shall be
less than 0,030 nm.
5.1.3 Minimum short-term precision
Calculate the short-term precision according to the Annex A, Clause A.2. The relative standard deviation (RSD)
shall not exceed 1 % of the mean absolute or ratioed intensities for concentrations 100 to 1 000 times the LOD
(5.1.4). For concentrations 10 to 100 times the LOD (5.1.4), the RSD shall not exceed 5 %.
5.1.4 Limit of Detection (LOD) and Limit of Quantification (LOQ)
Calculate the LOD and LOQ, according to the Annex A, Clause A.3, for the analytical line used. The values shall be
below the values in Table 2.
4 © ISO 2012 – All rights reserved
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ISO/DIS 13933
Table 2 — Limit of detection (LOD) and limit of quantification (LOD)
Analytical line LOD LOQ
Element
nm mg/l mg/l
Ca 393,66 0,002 2 0,011
Mg 279,55 0,003 0 0,015
5.1.5 Graph linearity
The linearity of the calibration graph is checked by calculating the correlation coefficient. This coefficient shall be
higher than 0,999.
5.2 Polytetrafluoroethylene (PTFE) beakers with PTFE cover
NOTE Glass beakers and glass watch covers can also be used for determination of magnesium.
5.3 100 ml polypropylene or polyethylene terephthalate (PET) volumetric flask
NOTE Before the determination, namely that of low concentration of Ca and Mg, it is necessary to clean the beakers and
flasks thoroughly with the hydrochloric acid (4.3).
5.4 Filter media, 0,22 m pore size, 47 mm diameter PTFE or polycarbonate filter membrane.
5.5 Suction filter, including a clean suction flask and vacuum filtration device.
6 Sampling
Carry out sampling in accordance with ISO 14284 or appropriate national standards for steel.
7 Procedure
WARNING — Perchloric acid vapour may cause explosions in the presence of ammonia, nitrous fumes or organic
matter in general.
All glassware and plastic ware shall first be washed in hydrochloric acid (4.3), then in water. The quantities of
calcium and magnesium in the glassware and plastic ware can be checked by measuring the
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