ISO 19984-2:2025

International
Standard
ISO 19984-2
Second edition
Rubber and rubber products —
2025-06
Determination of biobased
content —
Part 2:
Biobased carbon content
Élastomères et produits à base d'élastomères — Détermination
de la teneur en composés biosourcés —
Partie 2: Teneur en carbone biosourcé
Reference number
© ISO 2025
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
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, and abbreviated terms . 2
3.1 Terms and definitions .2
3.2 Abbreviated terms .2
4 Principle . 2
5 Sampling . 3
6 Measuring method of biobased carbon content by determination of C content . 3
6.1 General .3
6.2 Sample preparation and two methods to determine C concentration . .4
6.3 Calculation of the biobased carbon content .4
6.3.1 General .4
6.3.2 Correction factor .4
TC
6.3.3 Calculation of χχ , the biobased carbon content by Method A (AMS) .
B
TC
6.3.4 Calculation of χχ , the biobased carbon content by Method B (LSC) .
B
6.3.5 Examples .6
7 Precision . 6
8 Test report . 6
Annex A (normative) Method A — Determination by accelerator mass spectrometry (AMS) . 7
Annex B (normative) Method B — Determination by liquid scintillation counter (LSC) .10
Annex C (informative) Examples of the determination of biobased carbon content .13
Annex D (informative) Determination of the biobased carbon content of a tyre . 14
Annex E (informative) Precision results from an interlaboratory test programme . 17
Bibliography . 19

iii
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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.
A list of all parts in the ISO 19984 series can be found on the ISO website.
This second edition cancels and replaces the first edition (ISO 19984-2:2017), which has been technically
revised.
The main changes are as follows:
— REF values after 2020 have been added in Table 2;
— several bibliographic entries have 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
Introduction
The use of biomass materials in rubber compounds helps to decrease the rubber industry’s dependence
on fossil resources. It is also expected to lead to a reduction of carbon dioxide emission, reducing global
warming and promoting a sustainable global environment.
In the ISO 19984 series, biomass is the term used for the biological material from living or recently living
organisms such as wood and agricultural waste materials.
Industrial scale biomass is now readily being grown from numerous types of plant sources and a variety of
tree species. Biomass also includes plant or animal matter used for the production of fibres or chemicals. It
can also include biodegradable wastes. Biomass excludes organic materials which have been transformed
by geological processes into substances, such as petroleum or coal. Although fossil fuels have their origin in
ancient biomass, they are not considered biomass by the generally accepted definition because they contain
carbon that has been “out” of the modern carbon cycle.
The composition of biomass is mainly carbon, hydrogen and oxygen. Nitrogen and small quantities of other
elements can also be found.
The ISO 19984 series specifies methods for the determination of the biobased content of rubber and rubber
products. The results will give manufacturers and users a quantitative indication of their contribution to the
preservation of the environment.
ISO 19984-1 specifies how to categorize constituents of rubber and rubber products and how to calculate
the biobased content using the compound formulation and the chemical structure of each constituent.
ISO 19984-2 specifies how to determine the biobased carbon content by radio chemical analyses, i.e.
determination of C. It can be obtained from the fraction of carbon atoms derived from biomass against
the whole amount of carbon atoms in the rubber or rubber products. The methods specified in ISO 19984-2
allow consumers to determine the biobased carbon content even when the formulation of the rubber is
unavailable.
ISO 19984-3 specifies how to separate rubber compounds into constituents, how to obtain each constituent's
composition ratio and how to determine the biobased carbon content of each constituent by chemical
analyses. Thus, the biobased mass content for each constituent can be derived and the biobased mass content
for the whole rubber can be obtained by summing up all the constituent values.

v
International Standard ISO 19984-2:2025(en)
Rubber and rubber products — Determination of biobased
content —
Part 2:
Biobased carbon content
WARNING 1 — 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 determine the applicability of any other restrictions.
WARNING 2 — Certain procedures specified in this document can involve the use or generation
of substances, or the generation of waste, that can constitute a local environmental hazard. It is the
responsibility of the user to refer to appropriate documentation on safe handling and disposal after use.
1 Scope
This document specifies measuring methods for the determination of biobased carbon contents in rubber
and rubber products, including polyurethanes. The methods focus on carbon atoms in rubber or rubber
products, and determine whether the carbon-containing component is biobased or not, judging from the
concentration of C, radiocarbon isotope.
This document applies to rubber and rubber products such as raw materials, materials and final products.
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 1382, Rubber — Vocabulary
ISO 1795, Rubber, raw natural and raw synthetic — Sampling and further preparative procedures
ISO 1928, Coal and coke — Determination of gross calorific value
ISO 4661-2, Rubber, vulcanized — Preparation of samples and test pieces — Part 2: Chemical tests
ISO 15528, Paints, varnishes and raw materials for paints and varnishes — Sampling
ISO 19242, Rubber — Determination of total sulfur content by ion chromatography
ISO 19984-1, Rubber and rubber products — Determination of biobased content — Part 1: General principles
and calculation methods using the formulation of the rubber compound

3 Terms, definitions, and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1382 and ISO 19984-1 and the
following apply.
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/
3.1.1
percent modern carbon
pMC
normalized and standardized value for the amount of the C isotope in a sample, calculated relative to the
1)
standardized and normalized C isotope amount of oxalic acid standard reference material, SRM 4990c
Note 1 to entry: The reference value of 100 % biobased carbon is given in Table 2.
3.1.2
C activity
relative concentration of radiocarbon C expressed as a counting of β-irradiation from the decayed
radiocarbon atoms per minute
Note 1 to entry: The unit of C activity is “dpm” (decay per minute).
14 14
Note 2 to entry: The C activity is determined relatively using standard reference material (SRM 4990c) whose C
activity is set at 13,56 dpm.
3.2 Abbreviated terms
AMS accelerator mass spectroscopy
dpm disintegrations per minute
LSC liquid scintillation-counter or liquid scintillation-counting
pMC percent modern carbon
REF reference value
SRM standard reference materials
4 Principle
This document specifies those methods to determine the biobased carbon contents derived from biomass
resources.
1) SRM 4990c is an example of a suitable product supplied by the US National Institute of Standards and Technology.
This information is given for the convenience of users of this document and does not constitute an endorsement by ISO of
the product named. Equivalent products may be used if they can be shown to lead to the same results.

When the formulation of the rubber product is available, the biobased carbon content can be calculated (see
ISO 19984-1). The biobased carbon content is defined as the amount of biobased carbon to the total carbon
in rubber or rubber products as shown in Formula (1):
C
TC B
χ = ×100 (1)
B
++
CC C
BF NB
where
TC
is the biobased carbon content (%);
χ
B
C C and C are the mass of biobased, fossil-based and non-biobased carbon, respectively.
B, F NB
When there is no available information for the rubber or the rubber product, the biobased carbon content
14 14
can be determined by the C concentration. Due to its radioactive decay, C hardly exists in fossil products
older than 20 000 years to 30 000 years. Therefore, the C present in products is estimated to have come
from recent atmospheric carbon dioxide, and consequently, it can be considered as a tracer of recently
produced bio-products.
The biobased carbon content values determined in accordance with this document can also be compared to
the theoretical values calculated from the formulation, so that the reliability of the information about the
rubber in the rubber product is confirmed.
In order to determine the biobased mass content for raw rubber, organic ingredient, rubber products or
separated constituents, refer to ISO 19984-3.
5 Sampling
5.1 In the case of latex, carry out sampling in accordance with ISO 123 and dry the sample in accordance
with ISO 124.
5.2 In the case of raw material, carry out sampling in accordance with ISO 15528.
5.3 In the case of raw rubber, carry out sampling in accordance with ISO 1795.
5.4 In the case of vulcanized rubber, carry out sampling in accordance with ISO 4661-2.
NOTE The procedure of washing the surface of samples by acid and alkaline solution, which is a familiar
preparation process for carbon dating, is not necessary.
6 Measuring method of biobased carbon content by determination of C content
6.1 General
Sample preparation and two methods for the determination of the C content are described in this
document. With these modular approaches, it is possible for normally equipped laboratories to prepare
samples and choose either method to determine the C content with their own equipment or to outsource
the determination process to other laboratories that are specialized in this technique.
For the collection of the C from the sample, commonly accepted methods for the conversion of the carbon
present in the sample to carbon dioxide are adopted as indicated in Figure 1 (see also A.4.1 and B.4.1).
For the measurement of the C content, two methods are adopted that have been generally accepted as age
determination methods as indicated in Figure 1 (see also Annex A and Annex B).
NOTE: See Annex A for information regarding the accelerator mass spectrometry (AMS) method and
Annex B for information regarding the liquid scintillation counter (LSC) method.

Figure 1 — Outline for the determination of biobased carbon content
6.2 Sample preparation and two methods to determine C concentration
Carry out an oxidation of the sample as specified in A.4.1 and B.4.1. A complete oxidization of all the carbons
present in the sample shall be performed in order to obtain exact results. The measurement shall be made
according to one of the following two methods:
— Method A — Accelerator mass spectrometry (AMS): Direct determination of the isotope abundance of
C, specified in Annex A.
— Method B — Liquid scintillation counter (LSC): Indirect determination of the isotope abundance of C
through its emission of beta-particles (interaction with scintillation molecules), specified in Annex B.
The comparison between these test methods is given in Table 1.
Table 1 — Characteristics of the measurement methods of C
Relative standard
Method Determination Sample amount Measurement time
deviation
Method A Relative ratios between
1 mg to 10 mg 10 min to 30 min 0,2 % to 2,0 %
12 13 14
(AMS) isotope C, C and C
Method B
β counts of C decay 0,5 mg to 2,0 g 4 h to 24 h 0,2 % to 10 %
(LSC)
6.3 Calculation of the biobased carbon content
6.3.1 General
TC
The biobased carbon content as a fraction to the total carbon content, χ , using the C content value, is
B
determined by calculation from one of the test methods specified in 6.3.3 or 6.3.4, and applying the
correction factor in Table 2.
6.3.2 Correction factor
Before the above-ground hydrogen bomb testing (beginning approximately in 1955 and terminated in 1962),
the atmospheric C level was constant with a few percent range of change for the past millennium. Hence, a

sample grown before 1955 has a well-defined “modern” C activity, and the fossil contribution was able to
be determined in a straightforward way. After that, C generated during the bomb-testing era increased the
14 14
atmospheric C level up to 200 % (pMC) and 27,12 dpm ( C activity) in 1962. The values declined gradually,
however, to 100 % (pMC) and 13,56 dpm ( C activity), respectively by 2019, because the large emission of
14 12 14
fossil C during the last decades have contributed to the decrease of the atmospheric C/ C (the ratio of C
to C). The REF value of 100 % biobased carbon is indicated in Table 2 in accordance with ASTM D6866.
Table 2 — REF value of 100 % biobased carbon in determined year
Year REF (pMC, %)
2015 102,0
2016 101,5
2017 101,0
2018 100,5
2019 100,0
2020 100,0
2021 100,0
2022 100,0
2023 100,0
2024 99,7
2025 99,4
2026 99,1
2027 to be determined
For the calculation of the biobased carbon content, a REF value for harvest year of biomass in Table 2 is used
for Formula (2) and Formula (3).
NOTE A hundred (100) % pMC obtained by AMS measurement (Method A) corresponds to 13,56 dpm obtained by
LSC measurement (Method B).
If production or harvest year of resource biomass using in rubber product is unknown, 100,0 REF value is
used. This is reported in the test report.
TC
6.3.3 Calculation of χχ , the biobased carbon content by Method A (AMS)
B
TC
Calculate the biobased carbon content as a fraction of total carbon, χ , expressed as a percentage, using
B
Formula (2) (see Annex A):
p
TC S
χ =×100 (2)
B
R
where
p is the measured value, expressed in pMC, of the sample;
S
R is the reference value, expressed in pMC (see 6.3.2).

TC
6.3.4 Calculation of χχ , the biobased carbon content by Method B (LSC)
B
TC
Calculate the biobased carbon content as a fraction of total carbon, χ , expressed as a percentage, using
B
Formula (3) (see Annex B):
C
activity
TC
χ = ×100 (3)
B
R
13,56××m
where
14 14
C is the C activity, expressed in dpm, of the sample obtained by calculation when using
activity
Method B (see Annex B);
R is the reference value, expressed in pMC, of the sample (see 6.3.2);
m is the mass, expressed in grams, of the sample.
6.3.5 Examples
For examples of biobased carbon content determination, see Annexes C and D.
7 Precision
See Annex E.
8 Test report
The test report shall include at least the following information:
2)
a) a reference to this document, i.e. ISO 19984-2:— ;
b) all information necessary for complete identification of the rubber material or product tested, including
the origin of the biomass from which the material or product is constituted;
c) test method used for the determination of the C content (Method A or B);
d) information on whether δ C correction was applied or not (see A.5);
e) me
...