ISO 19050:2021
(Main)Rubber, raw, vulcanized — Determination of metal content by ICP-OES
Rubber, raw, vulcanized — Determination of metal content by ICP-OES
This document describes the method of determination of both major and trace levels of metal contents in rubber — raw, vulcanized — by ICP-OES.
Caoutchouc brut, vulcanisé — Dosage de la teneur en métaux par ICP-OES
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INTERNATIONAL ISO
STANDARD 19050
Second edition
2021-10
Rubber, raw, vulcanized —
Determination of metal content by
ICP-OES
Caoutchouc brut, vulcanisé — Dosage de la teneur en métaux par
ICP-OES
Reference number
ISO 19050:2021(E)
© ISO 2021
---------------------- Page: 1 ----------------------
ISO 19050:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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 the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
© ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 19050:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 2
6 Apparatus . 2
7 Calibration .4
8 Sample preparation .4
8.1 General . 4
8.2 Sampling . 5
8.3 Decomposition of organic matter . 5
8.3.1 Methods of destruction . 5
8.3.2 Wet oxidation . 5
8.3.3 Dry ashing . 5
8.3.4 Microwave digestion . 6
8.4 Preparation of standard solution and test solution. 7
9 Procedure .7
10 Test report .10
Annex A (normative) Calibration schedule . .11
Annex B (informative) Process flow of atomization of sample in ICP-OES .12
Bibliography .13
iii
© ISO 2021 – All rights reserved
---------------------- Page: 3 ----------------------
ISO 19050:2021(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 of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 45, Rubber and rubber products,
Subcommittee SC 2, Testing and analysis.
This second edition cancels and replaces the first edition (ISO 19050:2015), of which it constitutes a
minor revision.
The main changes compared to the previous edition are as follows:
— the CAS numbers have been added for all chemicals listed in this document;
— Clause 3 on “Terms and definitions” has been added.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
© ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 19050:2021(E)
Introduction
The ICP-OES (inductively coupled plasma – optical emission spectrophotometer) instrument is used to
determine the concentrations of certain elements in materials of interest. The main advantage of ICP-
OES over the AAS (atomic absorption spectroscopy) techniques in general is its multi-element capability,
its longer linear dynamic ranges and fewer condensed phase interferences. In addition, besides the
refractory compound-forming elements, elements such as iodine, phosphorus and sulfur are detected
with more sensitivity by the ICP-OES technique. ICP-OES is also known as ICP-AES (inductively coupled
plasma – atomic emission spectrophotometer).
ICP-OES was first introduced as a technique for trace elemental analysis. The technique experiences the
least interference of any of the commonly used analytical atomic spectrometry techniques. Chemical
interferences are largely eliminated by the high temperature of the plasma. Physical interferences can
be compensated for by taking advantage of the ICP’s multi-element capability.
In ICP-OES, the light emitted by the excited atoms and ions in the plasma is measured to obtain
information about the sample. Because the excited species in the plasma emit light at several different
wavelengths, the emission from the plasma is polychromatic. This polychromatic radiation has to be
separated into individual wavelengths so the emission from each excited species can be identified and
its intensity can be measured without interference from emission at other wavelengths.
An important feature of the ICP that is not common to most other emission sources is that since the
sample aerosol is introduced through the centre of the ICP, it can be surrounded by the high temperature
plasma for a comparatively long time, approximately 2 ms. It is this long residence time of the analyte
particles in the centre of the plasma that is largely responsible for the lack of matrix interferences in
the ICP.
The determination described in this document is important with respect to product safety and the
environment. ICP-OES is a state-of-the art instrument for accurate detection of the trace metals in raw
and vulcanized samples of rubber including latex.
v
© ISO 2021 – All rights reserved
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 19050:2021(E)
Rubber, raw, vulcanized — Determination of metal content
by ICP-OES
WARNING 1 — Persons using this document should be familiar with normal laboratory practice.
This document does not purport to address all of the safety problems, if any, associated with its
use. It is the responsibility of the user to establish appropriate safety and health practices and to
ensure compliance with any national regulatory conditions.
WARNING 2 — Certain procedures specified in this document may involve the use or generation
of substances, or the generation of waste, that could constitute a local environmental hazard.
Reference should be made to appropriate documentation on safe handling and disposal after
use.
1 Scope
This document describes the method of determination of both major and trace levels of metal contents
in rubber — raw, vulcanized — by ICP-OES.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 123, Rubber latex — Sampling
ISO 124, Latex, rubber — Determination of total solids content
ISO 1795, Rubber, raw natural and raw synthetic — Sampling and further preparative procedures
ISO 18899:2013, Rubber — Guide to the calibration of test equipment
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Principle
An aqueous sample is converted to an aerosol via a nebulizer. The aerosol is transported to the
inductively coupled plasma which has a high temperature zone (8 000 °C to 10 000 °C). The analytes
are heated (excited) to different (atomic and/or ionic) states and produce characteristic optical
emissions. These emissions are separated based on their respective wavelengths and their intensities
are measured (spectrometry). The intensities are proportional to the concentrations of analytes in the
aqueous sample. The quantification is carried out via an external multipoint linear standardization
obtained by comparing the emission intensity of an unknown sample with that of a standard sample. A
process flow of atomization of sample in ICP-OES is shown in Annex B.
1
© ISO 2021 – All rights reserved
---------------------- Page: 6 ----------------------
ISO 19050:2021(E)
5 Reagents
Use only reagents of recognized analytical grade, unless otherwise specified, and distilled or deionized
water or water of equivalent purity.
5.1 Ultra-pure grade of concentrated nitric acid (CAS 7697-37-2), density 1,42 g/ml.
5.2 Ultra-pure grade of concentrated hydrochloric acid (CAS 7647-01-0), density 1,19 g/ml.
5.3 Ultra-pure grade of concentrated sulfuric acid (CAS 7664-93-9), density 1,83 g/ml.
5.4 Multi-element primary standard solution, traceable to NIST (National Institute of Standards
and Technology) or any national metrological institute (NMI).
5.5 Single-element primary standard solutions, traceable to NIST or any NMI.
5.6 Ammonium oxalate (CAS 6009-70-7) saturated solution.
5.7 Yttrium (CAS 7440-65-5) solution, 1 000 μg/g.
5.8 Diluted nitric acid.
5.9 Diluted HCl.
6 Apparatus
Usual laboratory apparatus and glassware and, in particular, the following.
6.1 ICP-OES system. A portion of the photons emitted by the ICP is collected with a lens or a concave
mirror. This focusing optic forms an image of the ICP on the entrance aperture of a wavelength selection
device such as a monochromator. The particular wavelength exiting the monochromator is converted to
an electrical signal by a photodetector. The signal is amplified and processed by the detector electronics,
then displayed and stored by a personal computer. Different components of the instruments are shown
in Figure 1. A description of the different components is given in 6.1.1 to 6.1.4.
6.1.1 Test solution introduction, to produce a steady aerosol of very fine droplets. There are three
basic parts to the sample introduction system as listed in 6.1.1.1 to 6.1.1.3.
6.1.1.1 Peristaltic pump, to draw up the test solution and deliver it to the nebulizer.
6.1.1.2 Nebulizer, to convert the solution to an aerosol that is sent to the spray chamber.
6.1.1.3 Spray chamber, to filter out the large, uneven droplets from the aerosol.
6.1.2 Energy source, to get atoms sufficiently energized such that they emit light. There are three
basic parts to the energy source as listed in 6.1.2.1 to 6.1.2.3.
6.1.2.1 Radio frequency generator, to generate an oscillating electro-magnetic field at a frequency
of 27,12 MHz. This radiation is directed to the load coil. Equipment is also available with electro-
magnetic field at a frequency of 40,68 MHz.
6.1.2.2 Load coil, to deliver the radiation to the torch.
2
© ISO 2021 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 19050:2021(E)
6.1.2.3 Torch, having argon flowing through it which will form a plasma in the RF field.
6.1.3 Spectrometer, to diffract the white light from the plasma into wavelengths. There are several
types of spectrometers used for ICP. Regardless of type, all of them use a diffraction grating.
6.1.4 Detector, to measure the intensity of the wavelengths. The detector is a silicon chip that is
composed of many individual photo-active sections called “picture elements”. These picture elements,
or pixels, will build up charge as photons impinge on them. Individual pixels are of a size such that they
can be used to measure individual wavelengths.
6.2 Analytical balance, capable of weighing to the nearest ± 0,1 mg.
6.3 Micro syringe, calibrated.
6.4 Hot plate.
6.5 Pipettes, of different capacities i.e. 10 ml, 20 ml.
6.6 Micro-Kjeldahl digestion flask.
6.7 Muffle furnace.
6.8 TFM (tetrafluoroethylene modified) vessel.
6.9 Microwave digestion system.
6.10 Sample rack of autosampler.
1)
6.11 Filter paper, Whatman No. 44 .
1) Example of a suitable product available commercially. This information is given for the convenience of users of
this document and does not constitute an endorsement by ISO of this product. Equivalent products may be used if
they can be shown to lead to the same results.
3
© ISO 2021 – All rights reserved
---------------------- Page: 8 ----------------------
ISO 19050:2021(E)
6.12 Silica or platinum dish.
Key
a
1 sample 5 spray chamber
...
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 19050
ISO/TC 45/SC 2
Rubber, raw, vulcanized —
Secretariat: JISC
Determination of metal content by
Voting begins on:
202105-26 ICP-OES
Voting terminates on:
Caoutchouc brut, vulcanisé — Dosage de la teneur en métaux par
202108-18
ICP-OES
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 SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO
ISO/FDIS 19050:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2021
---------------------- Page: 1 ----------------------
ISO/FDIS 19050:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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 the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 19050:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 2
6 Apparatus . 2
7 Calibration . 4
8 Sample preparation . 4
8.1 General . 4
8.2 Sampling . 5
8.3 Decomposition of organic matter . 5
8.3.1 Methods of destruction . 5
8.3.2 Wet oxidation . 5
8.3.3 Dry ashing . 5
8.3.4 Microwave digestion . . 6
8.4 Preparation of standard solution and test solution . 7
9 Procedure. 7
10 Test report .10
Annex A (normative) Calibration schedule .11
Annex B (informative) Process flow of atomization of sample in ICP-OES .12
Bibliography .13
© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/FDIS 19050:2021(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 nongovernmental, 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 of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 45, Rubber and rubber products,
Subcommittee SC 2, Testing and analysis.
This second edition cancels and replaces the first edition (ISO 19050:2015), of which it constitutes a
minor revision.
The main changes compared to the previous edition are as follows:
— the CAS numbers have been added for all chemicals listed in this document;
— Clause 3 on “Terms and definitions” has been added.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 19050:2021(E)
Introduction
The ICP-OES (inductively coupled plasma – optical emission spectrophotometer) instrument is used to
determine the concentrations of certain elements in materials of interest. The main advantage of ICP
OES over the AAS (atomic absorption spectroscopy) techniques in general is its multi-element capability,
its longer linear dynamic ranges and fewer condensed phase interferences. In addition, besides the
refractory compound-forming elements, elements such as iodine, phosphorus and sulfur are detected
with more sensitivity by the ICP-OES technique. ICP-OES is also known as ICP-AES (inductively coupled
plasma – atomic emission spectrophotometer).
ICP-OES was first introduced as a technique for trace elemental analysis. The technique experiences the
least interference of any of the commonly used analytical atomic spectrometry techniques. Chemical
interferences are largely eliminated by the high temperature of the plasma. Physical interferences can
be compensated for by taking advantage of the ICP’s multi-element capability.
In ICP-OES, the light emitted by the excited atoms and ions in the plasma is measured to obtain
information about the sample. Because the excited species in the plasma emit light at several different
wavelengths, the emission from the plasma is polychromatic. This polychromatic radiation has to be
separated into individual wavelengths so the emission from each excited species can be identified and
its intensity can be measured without interference from emission at other wavelengths.
An important feature of the ICP that is not common to most other emission sources is that since the
sample aerosol is introduced through the centre of the ICP, it can be surrounded by the high temperature
plasma for a comparatively long time, approximately 2 ms. It is this long residence time of the analyte
particles in the centre of the plasma that is largely responsible for the lack of matrix interferences in the
ICP.
The determination described in this document is important with respect to product safety and the
environment. ICPOES is a stateofthe art instrument for accurate detection of the trace metals in raw
and vulcanized samples of rubber including latex.
© ISO 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 19050:2021(E)
Rubber, raw, vulcanized — Determination of metal content
by ICP-OES
WARNING 1 — Persons using this document should be familiar with normal laboratory practice.
This document does not purport to address all of the safety problems, if any, associated with its
use. It is the responsibility of the user to establish appropriate safety and health practices and to
ensure compliance with any national regulatory conditions.
WARNING 2 — Certain procedures specified in this document may involve the use or generation
of substances, or the generation of waste, that could constitute a local environmental hazard.
Reference should be made to appropriate documentation on safe handling and disposal after
use.
1 Scope
This document describes the method of determination of both major and trace levels of metal contents
in rubber — raw, vulcanized — by ICP-OES.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 123, Rubber latex — Sampling
ISO 124, Latex, rubber — Determination of total solids content
ISO 1795, Rubber, raw natural and raw synthetic — Sampling and further preparative procedures
ISO 18899:2013, Rubber — Guide to the calibration of test equipment
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Principle
An aqueous sample is converted to an aerosol via a nebulizer. The aerosol is transported to the
inductively coupled plasma which has a high temperature zone (8 000 °C to 10 000 °C). The analytes
are heated (excited) to different (atomic and/or ionic) states and produce characteristic optical
emissions. These emissions are separated based on their respective wavelengths and their intensities
are measured (spectrometry). The intensities are proportional to the concentrations of analytes in the
aqueous sample. The quantification is carried out via an external multipoint linear standardization
obtained by comparing the emission intensity of an unknown sample with that of a standard sample. A
process flow of atomization of sample in ICP-OES is shown in Annex B.
© ISO 2021 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO/FDIS 19050:2021(E)
5 Reagents
Use only reagents of recognized analytical grade, unless otherwise specified, and distilled or deionized
water or water of equivalent purity.:
5.1 Ultra-pure grade of concentrated nitric acid (CAS 7697-37-2), density 1,42 g/ml.
5.2 Ultra-pure grade of concentrated hydrochloric acid (CAS 7647-01-0), density 1,19 g/ml.
5.3 Ultra-pure grade of concentrated sulfuric acid (CAS 7664-93-9), density 1,83 g/ml.
5.4 Multi-element primary standard solution, traceable to NIST (National Institute of Standards
and Technology) or any national metrological institute (NMI).
5.5 Single-element primary standard solutions, traceable to NIST or any NMI.
5.6 Ammonium oxalate (CAS 6009707) saturated solution.
5.7 Yttrium (CAS 7440655) solution, 1 000 μg/g.
5.8 Diluted nitric acid.
5.9 Diluted HCl.
6 Apparatus
Usual laboratory apparatus and glassware and, in particular, the following.
6.1 ICP-OES system. A portion of the photons emitted by the ICP is collected with a lens or a concave
mirror. This focusing optic forms an image of the ICP on the entrance aperture of a wavelength selection
device such as a monochromator. The particular wavelength exiting the monochromator is converted to
an electrical signal by a photodetector. The signal is amplified and processed by the detector electronics,
then displayed and stored by a personal computer. Different components of the instruments are shown
in Figure 1. A description of the different components is given in 6.1.1 to 6.1.4.
6.1.1 Test solution introduction, to produce a steady aerosol of very fine droplets. There are three
basic parts to the sample introduction system as listed in 6.1.1.1 to 6.1.1.3.
6.1.1.1 Peristaltic pump, to draw up the test solution and deliver it to the nebulizer.
6.1.1.2 Nebulizer, to convert the solution to an aerosol that is sent to the spray chamber.
6.1.1.3 Spray chamber, to filter out the large, uneven droplets from the aerosol.
6.1.2 Energy source, to get atoms sufficiently energized such that they emit light. There are three
basic parts to the energy source as listed in 6.1.2.1 to 6.1.2.3.
6.1.2.1 Radio frequency generator, to generate an oscillating electro-magnetic field at a frequency of
27,12 MHz. This radiation is directed to the load coil. Equipment is also available with electro-magnetic
field at a frequency of 40,68 MHz.
6.1.2.2 Load coil, to deliver the radiation to the torch.
2 © ISO 2021 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/FDIS 19050:2021(E)
6.1.2.3 Torch, having argon flowing through it which will form a plasma in the RF field.
6.1.3 Spectrometer, to diffract the white light from the plasma into wavelengths. There are several
types of spectrometers used for ICP. Regardless of type, all of them use a diffraction grating.
6.1.4 Detector, to measure the intensity of the wavelengths. The detector is a silicon chip that is
composed of many individual photo-active sections called “picture elements”. These picture elements, or
pixels, will build up charge as photons impinge on them. Individual pixels are of a size such that they can
be used to measure individual wavelengths.
6.2 Analytical balance, capable of weighing to the nearest ± 0,1 mg.
6.3 Micro syringe, calibrated.
6.4 Hot plate.
6.5 Pipettes, of different capacities i.e. 10 ml, 20 ml.
6.6 Micro-Kjeldahl digestion flask.
6.7 Muffle furnace.
6.8 TFM (tetrafluoroethylene modified) vessel.
6.9 Microwave digestion system.
6.10 Sample rack of autosampler.
1)
6.11 Filter paper, Whatman No. 44 .
1) Example of a suitable product available commercially. This information is given for the convenience of users of
this document and does not constitute an
...
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