ISO/FDIS 24187

Principles for the analysis of microplastics present in the environment

Principes d'analyse des microplastiques présents dans l'environnement

General Information

• Status: Not Published
• ICS: 13.020.01 - Environment and environmental protection in general
• ICS: 83.080.01 - Plastics in general
• Technical Committee: ISO/TC 61/SC 14 - Environmental aspects
• Drafting Committee: ISO/TC 61/SC 14/WG 4 - Characterization of plastics leaked into the environment (including microplastics) and quality control criteria of respective methods
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 27-Apr-2023
• Completion Date: 27-Apr-2023

Standards Content (Sample)

ISO/DIS 24187:2021(E)
2022-12-0502-08
ISO/FDIS 24187:20222023
ISO TC 61/SC 14/WG 4
Secretariat: DIN
Principles for the analysis of microplastics present in the environment
---------------------- Page: 1 ----------------------
ISO/FDIS 24187:20222023(E)
© ISO 2022

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: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.orgwww.iso.org
Published in Switzerland
ii © ISO 2022 – All rights reserved
ii © ISO 2023 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 24187:2022(E)
Contents

Foreword .......................................................................................................................................................................... v

Introduction.................................................................................................................................................................... vi

1 Scope .................................................................................................................................................................... 1

2 Normative references .................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................... 1

4 General Aspects ................................................................................................................................................ 3

5 General requirements for all analytical steps ...................................................................................... 4

6 Identification of appropriate detection methods ................................................................................ 5

6.1 General ................................................................................................................................................................ 5

6.2 Classification of detection tools ................................................................................................................. 5

6.3 Identification of addressed objective ....................................................................................................... 6

7 Sampling of water ............................................................................................................................................ 7

7.1 General ................................................................................................................................................................ 7

7.2 Sampling volume ............................................................................................................................................. 7

7.3 Mesh sizes .......................................................................................................................................................... 7

7.4 Filter materials ................................................................................................................................................. 8

7.5 Sampling Devices ............................................................................................................................................. 8

8 Sampling of terrestric, semiterrestric and subhydric soils ............................................................. 8

8.1 General aspects ................................................................................................................................................ 8

8.2 Sampling of terrestrial soils ........................................................................................................................ 9

8.3 Sampling of semiterrestrial soils ............................................................................................................... 9

8.4 Sampling of subhydric soils (sediments) ................................................................................................ 9

9 Sampling of air .................................................................................................................................................. 9

9.1 Indoor Air ........................................................................................................................................................... 9

9.2 Outdoor Air ..................................................................................................................................................... 10

10 Sampling of sludges and other similar materials ............................................................................. 10

11 Sampling of mineral and other inorganic materials ........................................................................ 10

12 Sampling of biota .......................................................................................................................................... 10

13 Sample preparation ..................................................................................................................................... 11

13.1 General aspects ............................................................................................................................................. 11

13.2 Drying ............................................................................................................................................................... 11

13.3 Milling and grinding .................................................................................................................................... 12

13.4 Removal of inorganic matter .................................................................................................................... 12

13.5 Removal of organic matter ........................................................................................................................ 12

14 Data Processing ............................................................................................................................................. 12

14.1 General Aspects ............................................................................................................................................. 12

14.2 Single spectra / chromatogram interpretation ................................................................................. 13

14.3 Interpretation of large spectra / chromatogram datasets ............................................................ 13

Formatted: Font: 11 pt

15 Aspects of analytical quality assurance ................................................................................................ 13

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© ISO 2022 – All rights reserved iii
© ISO 2023 – All rights reserved iii
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ISO/FDIS 24187:20222023(E)

15.1 Reference Materials ..................................................................................................................................... 13

15.2 Performance of interlaboratory comparison tests .......................................................................... 15

Annex A (informative) Advanced Data Processing ......................................................................................... 17

A.1 Introduction to advanced data processing ......................................................................................... 17

A.2 Methods for determining particle number and sizes (Spectroscopic procedures) ............. 18

A.2.1 Chemical structure determination ......................................................................................................... 18

A.2.2 Spatial Analysis ............................................................................................................................................. 18

A.3 Methods for determining mass content (thermoanalytical and chemical methods) .......... 19

A.3.1 Chemical structure determination. ........................................................................................................ 19

A.3.2 Quantification of mass content ................................................................................................................ 19

A.3.3 General recommendations for evaluating databases and data processing approaches .... 20

A.3.4 Classification .................................................................................................................................................. 20

A.3.5 Regression ....................................................................................................................................................... 21

A.4 Data file formats ........................................................................................................................................... 21

A.5 A practical example for computing classification performance measures ............................. 21

Bibliography ................................................................................................................................................................. 23

Foreword .......................................................................................................................................................................... v

Introduction.................................................................................................................................................................... vi

1 Scope .................................................................................................................................................................... 1

2 Normative references .................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................... 1

4 General Aspects ................................................................................................................................................ 3

5 General requirements for all analytical steps ...................................................................................... 4

6 Identification of appropriate detection methods ................................................................................ 5

6.1 General ................................................................................................................................................................ 5

6.2 Classification of detection tools ................................................................................................................. 5

6.3 Identification of addressed objective ....................................................................................................... 6

7 Sampling of water ............................................................................................................................................ 7

7.1 General ................................................................................................................................................................ 7

7.2 Sampling volume ............................................................................................................................................. 7

7.3 Mesh sizes .......................................................................................................................................................... 7

7.4 Filter materials ................................................................................................................................................. 8

7.5 Sampling Devices ............................................................................................................................................. 8

8 Sampling of terrestric, semiterrestric and subhydric soils ............................................................. 8

8.1 General aspects ................................................................................................................................................ 8

8.2 Sampling of terrestrial soils ........................................................................................................................ 9

8.3 Sampling of semiterrestrial soils ............................................................................................................... 9

8.4 Sampling of subhydric soils (sediments) ................................................................................................ 9

iv © ISO 2022 – All rights reserved
iv © ISO 2023 – All rights reserved
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ISO/FDIS 24187:2022(E)

9 Sampling of air .................................................................................................................................................. 9

9.1 Indoor Air ........................................................................................................................................................... 9

9.2 Outdoor Air ..................................................................................................................................................... 10

10 Sampling of sludges and other similar materials ............................................................................. 10

11 Sampling of mineral and other inorganic materials ........................................................................ 10

12 Sampling of biota .......................................................................................................................................... 10

13 Sample preparation ..................................................................................................................................... 11

13.1 General aspects ............................................................................................................................................. 11

13.2 Drying ............................................................................................................................................................... 11

13.3 Milling and grinding .................................................................................................................................... 12

13.4 Removal of inorganic matter .................................................................................................................... 12

13.5 Removal of organic matter ........................................................................................................................ 12

14 Data Processing ............................................................................................................................................. 12

14.1 General Aspects ............................................................................................................................................. 12

14.2 Single spectra / chromatogram interpretation ................................................................................. 13

14.3 Interpretation of large spectra / chromatogram datasets ............................................................ 13

15 Aspects of analytical quality assurance ................................................................................................ 13

15.1 Reference Materials ..................................................................................................................................... 13

15.2 Performance of interlaboratory comparison tests .......................................................................... 15

Annex A (informative) Advanced Data Processing ......................................................................................... 17

A.1 Introduction to advanced data processing ......................................................................................... 17

A.2 Methods for determining particle number and sizes (Spectroscopic procedures) ............. 18

A.2.1 Chemical structure determination ......................................................................................................... 18

A.2.2 Spatial Analysis ............................................................................................................................................. 18

A.3 Methods for determining mass content (thermoanalytical and chemical methods) .......... 19

A.3.1 Chemical structure determination. ........................................................................................................ 19

A.3.2 Quantification of mass content ................................................................................................................ 19

A.3.3 General recommendations for evaluating databases and data processing approaches .... 20

A.3.4 Classification .................................................................................................................................................. 20

A.3.5 Regression ....................................................................................................................................................... 21

A.4 Data file formats ........................................................................................................................................... 21

A.5 A practical example for computing classification performance measures ............................. 21

Bibliography ................................................................................................................................................................. 23

Formatted: Font: 11 pt
Formatted: Line spacing: Exactly 11 pt
© ISO 2022 – All rights reserved v
© ISO 2023 – All rights reserved v
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ISO/FDIS 24187:20222023(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/directiveswww.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/patentswww.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.htmlwww.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 14,

Environmental aspects, in collaboration with the European Committee for Standardization (CEN)

Technical Committee CEN/TC 249, Plastics, in accordance with the Agreement on technical cooperation

between ISO and CEN (Vienna Agreement).

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.htmlwww.iso.org/members.html.
vi © ISO 2022 – All rights reserved
vi © ISO 2023 – All rights reserved
---------------------- Page: 6 ----------------------
ISO/FDIS 24187:2022(E)
Introduction

The analysis of plastics and microplastics is a new field in relation to other areas of environmental

analysis. A large number of scientific publications exist, but they do not apply a uniform analysis, which

makes it difficult to compare the results.

This document sets out key principles for the investigation of microplastics in the environment, which

should be taken into account in the subsequent development of specific procedures for sampling, sample

preparation and detection. A large number of the principles described in this document can be applied,

analogously, to other matrices and products, including foodstuffs and drinking water. The objective is to

present a pool of methods and notes that is as harmonized as possible and to make it available for use in

science, businesses and administrations.

What is true for analytics is also true for definitions in the same way. On the one hand, the terms used in

this document are based on existing definitions in the subject area, but on the other hand, analytical

requirements are also taken into account. This applies, for example, to the term “large microplastics”. The

particle size to be investigated is closely related to the detection method to be selected. In the course of

future specific work, it can be necessary to modify existing definitions slightly and adapt them to new

knowledge and requirements.

With regard to the definitions, including the ideas of size classes, it is pointed out, that the discussion is

ongoing in various technical committees in ISO and other standardization bodies. The definitions in this

document show the status in ISO TC 61/SC 14. The definitions chosen in this document are adapted from

the ISO report on plastics. The basis of the classification is based on the metric sizes and the associated

designations. Microplastics is thus derived from micrometres.

NOTE Microplastics can also stem from different sources not specifically mentioned in this document, such as

textiles, paints and tyres.
Formatted: Font: 11 pt
Formatted: Line spacing: Exactly 11 pt
© ISO 2022 – All rights reserved vii
© ISO 2023 – All rights reserved vii
---------------------- Page: 7 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/DISFDIS 24187:20222023(E)
Principles for the analysis of microplastics present in the
environment
1 Scope

This document describes the principles to be followed in the analysis of microplastics in various

environmental matrices. This includes the unique particle size classification of plastics, the use of certain

apparatus with regard to sampling, sample preparation, and the determination of representative sample

quantities.

The purpose of this document is to specify minimum requirements until specific standards for the

different case situations are available. This is important to ensure that the development of the specific

standards is done on a consistent basis to ensure that comparison or correlation of results is possible.

This document does not include requirements for monitoring actions.
2 Normative references
There are no normative references in this document.

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 472, Plastics — Vocabulary
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 472 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://www.iso.org/obphttps://www.iso.org/obp

— IEC Electropedia: available at https://www.electropedia.org/https://www.electropedia.org/

3.1
large microplastic

any solid plastic particle insoluble in water with any dimension between 1 mm and 5 mm

Note 1 to entry: Microplastics may show various shapes.

Note 2 to entry: Typically, a large microplastics object represents an item consisting of plastics or a part of an end-

Formatted: Font: 11 pt
user product or a fragment of the respective item.
Formatted: Line spacing: Exactly 11 pt
© ISO 2022 – All rights reserved 1
© ISO 2022 – All rights reserved 1
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ISO/FDIS 24187:20222023(E)

[SOURCE: ISO/TR 21960:2020, 3.10, modified — term number in Note 1 to entry was removed.]

3.2
microplastic

any solid plastic particle insoluble in water with dimension between 1 µm and 1 000 µm (= 1 mm)

Note 1 to entry: Primary microplastics object represents a particle intentionally added to end-user products for

example cosmetic means, coatings, paints etc. Secondary microplastics object can also result as a fragment of the

respective item.

Note 2 to entry: Microplastics have regular and irregular shapes (see ISO 9276-6:20172008).

Note 3 to entry: The defined dimension is related to the longest length of the particle.

[SOURCE: ISO/TR 21960:2020, 3.9, modified — Note 1 to entry was removed, all other Notes to entry

were changed.]
3.3
additives

substances which are used to process plastics or to modify end use properties of plastics

Note 1 to entry: Important additives such as fillers/reinforced materials, softeners and flame retardants are

referenced according to ISO 1043-2 to ISO 1043-4.
4 General aspects

Microplastics is a term that comes along with different physical and chemical properties, such as shape,

size (range), type of polymer(s), presence of additives, presence of fillers, state of degradation and so on.

The amount of microplastics in a given matrix can be measured in different ways, i.e. as number (of

particles) or mass content/fraction in relation to the sample’s quantity, which itself can be based on

various units (volume, weight, etc.). Hence, before selecting a suitable (set of) method(s), the question(s)

to be answered and properties to be measured need to be specified carefully. This applies not only to

detection methods but also to the sampling and processing/preparation methods associated with them,

right up to the statistical evaluation of results.

A schematic representation of the interdependencies of microplastics analysis is shown in Figure 1. As a

rule, the objective or objectives of a measurement or a measurement program is/ are based on a clear

question/task or on an evaluation concept involving necessary assessment parameters, respectively (for

example integration into an overall ecological context, thresholds for monitoring). A suitable detection

method is then selected, which generates the desired result parameters (such as polymer type, mass

content, number, shape, size, degradation status).
2 © ISO 2022 – All rights reserved
2 © ISO 2023 – All rights reserved
---------------------- Page: 9 ----------------------
ISO/FDIS 24187:20222023(E)

Figure 1 — Schematic representation of interdependencies during microplastics analysis in

environmental and related matrices
5 General requirements for all analytical steps

All analytical steps (sampling, sample preparation, detection) shall be undertaken in plastics-free or low-

plastics working conditions. These include the avoidance of standard plastics products (for example

tubes, vessels). Contamination, especially cross-contamination shall be avoided, the user should avoid

using plastics equipment wherever possible. Instead, alternatives made of metal, glass or ceramics should

be used. As an exception and after it was proved by experiments (for example by characterizing the

container), types of plastics that are not to be detected or evaluated can be used as well. Care should be

taken that also personal protective equipment (e.g. lab coats, gloves) are also made of non-synthetic

material or material that does not interfere with the analyses. Recovery tests should be performed for

each analytical step.

If feasible, samples should be handled in laminar flow boxes in the laboratory or clean rooms (class 3

according to ISO 14644-1, especially during the preparation process of samples and during the

determination of particle numbers.

It shall be determined beforehand, whether a hygienization of samples is necessary. Sterilization is a

Formatted: Font: 11 pt

standard recommendation for the analysis of dry samples from wastewater, sewage sludge and organic

Formatted: Line spacing: Exactly 11 pt
© ISO 2022 – All rights reserved 3
© ISO 2023 – All rights reserved 3
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ISO/F
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 24187
ISO/TC 61/SC 14
Principles for the analysis of
Secretariat: DIN
microplastics present in the
Voting begins on:
2023-02-23 environment
Voting terminates on:
Principes d'analyse des microplastiques présents dans
2023-04-20
l'environnement
ISO/CEN PARALLEL PROCESSING
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 24187:2023(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 2023
---------------------- Page: 1 ----------------------
ISO/FDIS 24187:2023(E)
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 24187
ISO/TC 61/SC 14
Principles for the analysis of
Secretariat: DIN
microplastics present in the
Voting begins on:
environment
Voting terminates on:
Principes d'analyse des microplastiques présents dans
l'environnement
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
ISO/CEN PARALLEL PROCESSING

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.
RECIPIENTS OF THIS DRAFT ARE INVITED TO
ISO copyright office
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
CP 401 • Ch. de Blandonnet 8
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
CH-1214 Vernier, Geneva
DOCUMENTATION.
Phone: [phone]
IN ADDITION TO THEIR EVALUATION AS
Reference number
Email: [e-mail]
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/FDIS 24187:2023(E)
Website: www.iso.org
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
Published in Switzerland
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
© ISO 2023 – All rights reserved
NATIONAL REGULATIONS. © ISO 2023
---------------------- Page: 2 ----------------------
ISO/FDIS 24187:2023(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction .................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ..................................................................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................................................................... 1

4 General aspects ..................................................................................................................................................................................................... 2

5 General requirements for all analytical steps ..................................................................................................................... 2

6 Identification of appropriate detection methods ............................................................................................................. 3

6.1 General ........................................................................................................................................................................................................... 3

6.2 Detection techniques ........................................................................................................................................................................ 4

6.3 Identification of objective to be addressed ................................................................................................................... 4

7 Sampling of water ............................................................................................................................................................................................... 5

7.1 General ........................................................................................................................................................................................................... 5

7.2 Sampling volume ................................................................................................................................................................................... 5

7.3 Mesh sizes ................................................................................................................................................................................................... 6

7.4 Filter materials ....................................................................................................................................................................................... 6

8 Sampling of terrestrial, semiterrestrial and subhydric soils .............................................................................. 6

8.1 General ........................................................................................................................................................................................................... 6

8.2 Sampling of terrestrial soils ....................................................................................................................................................... 6

8.3 Sampling of semiterrestrial soils ........................................................................................................................................... 7

8.4 Sampling of subhydric soils (sediments) ......................................................................................................................... 7

9 Sampling of air ....................................................................................................................................................................................................... 7

9.1 Indoor air ..................................................................................................................................................................................................... 7

9.2 Outdoor air ................................................................................................................................................................................................. 7

10 Sampling of sludges and other similar materials ............................................................................................................. 7

11 Sampling of mineral and other inorganic materials ..................................................................................................... 8

12 Sampling of biota ................................................................................................................................................................................................. 8

13 Sample preparation ..........................................................................................................................................................................................8

13.1 General aspects ...................................................................................................................................................................................... 8

13.2 Drying ............................................................................................................................................................................................................. 9

13.3 Milling and grinding .......................................................................................................................................................................... 9

13.4 Removal of inorganic matter ..................................................................................................................................................... 9

13.5 Removal of organic matter .......................................................................................................................................................... 9

14 Data processing ..................................................................................................................................................................................................10

14.1 General aspects ................................................................................................................................................................................... 10

14.2 Single spectra/chromatogram interpretation ........................................................................................................ 10

14.3 Interpretation of large spectra/chromatogram data sets ............................................................................ 10

15 Aspects of analytical quality assurance ..................................................................................................................................11

15.1 Reference materials ........................................................................................................................................................................ 11

15.2 Performance of interlaboratory comparison tests..............................................................................................12

Annex A (informative) Advanced Data Processing ............................................................................................................................14

Bibliography .............................................................................................................................................................................................................................20

iii
© ISO 2023 – All rights reserved
---------------------- Page: 3 ----------------------
ISO/FDIS 24187:2023(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 61, Plastics, Subcommittee SC 14,

Environmental aspects, in collaboration with the European Committee for Standardization (CEN)

Technical Committee CEN/TC 249, Plastics, in accordance with the Agreement on technical cooperation

between ISO and CEN (Vienna Agreement).

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.
© ISO 2023 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 24187:2023(E)
Introduction

The analysis of plastics and microplastics is a new field in relation to other areas of environmental

analysis. A large number of scientific publications exist, but they do not apply a uniform analysis, which

makes it difficult to compare the results.

This document sets out key principles for the investigation of microplastics in the environment, which

should be taken into account in the subsequent development of specific procedures for sampling, sample

preparation and detection. A large number of the principles described in this document can be applied,

analogously, to other matrices and products, including foodstuffs and drinking water. The objective is

to present a pool of methods and notes that is as harmonized as possible and to make it available for use

in science, businesses and administrations.

What is true for analytics is also true for definitions in the same way. On the one hand, the terms used

in this document are based on existing definitions in the subject area, but on the other hand, analytical

requirements are also taken into account. This applies, for example, to the term “large microplastics”.

The particle size to be investigated is closely related to the detection method to be selected. In the

course of future specific work, it can be necessary to modify existing definitions slightly and adapt

them to new knowledge and requirements.

With regard to the definitions, including the ideas of size classes, it is pointed out, that the discussion

is ongoing in various technical committees in ISO and other standardization bodies. The definitions in

this document show the status in ISO TC 61/SC 14. The definitions chosen in this document are adapted

from the ISO report on plastics. The basis of the classification is based on the metric sizes and the

associated designations. Microplastics is thus derived from micrometres.

NOTE Microplastics can also stem from different sources not specifically mentioned in this document, such

as textiles, paints and tyres.
© ISO 2023 – All rights reserved
---------------------- Page: 5 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 24187:2023(E)
Principles for the analysis of microplastics present in the
environment
1 Scope

This document describes the principles to be followed in the analysis of microplastics in various

environmental matrices. This includes the unique particle size classification of plastics, the use of

certain apparatus with regard to sampling, sample preparation, and the determination of representative

sample quantities.

The purpose of this document is to specify minimum requirements until specific standards for the

different case situations are available. This is important to ensure that the development of the specific

standards is done on a consistent basis to ensure that comparison or correlation of results is possible.

This document does not include requirements for monitoring actions.
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 472, Plastics — Vocabulary
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 472 and the following apply.

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 https:// www .electropedia .org/
3.1
large microplastic

any solid plastic particle insoluble in water with any dimension between 1 mm and 5 mm

Note 1 to entry: Microplastics may show various shapes.

Note 2 to entry: Typically, a large microplastics object represents an item consisting of plastics or a part of an

end­user product or a fragment of the respective item.

[SOURCE: ISO/TR 21960:2020, 3.10, modified — term number in Note 1 to entry was removed.]

3.2
microplastic

any solid plastic particle insoluble in water with dimension between 1 µm and 1 000 µm (= 1 mm)

Note 1 to entry: Primary microplastics object represents a particle intentionally added to end-user products for

example cosmetic means, coatings, paints etc. Secondary microplastics object can also result as a fragment of the

respective item.

Note 2 to entry: Microplastics have regular and irregular shapes (see ISO 9276-6:2008).

Note 3 to entry: The defined dimension is related to the longest length of the particle.

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ISO/FDIS 24187:2023(E)

[SOURCE: ISO/TR 21960:2020, 3.9, modified — Note 1 to entry was removed, all other Notes to entry

were changed.]
3.3
additives

substances which are used to process plastics or to modify end use properties of plastics

Note 1 to entry: Important additives such as fillers/reinforced materials, softeners and flame retardants are

referenced according to ISO 1043­2 to ISO 1043­4.
4 General aspects

Microplastics is a term that comes along with different physical and chemical properties, such as shape,

size (range), type of polymer(s), presence of additives, presence of fillers, state of degradation and so

on. The amount of microplastics in a given matrix can be measured in different ways, i.e. as number

(of particles) or mass content/fraction in relation to the sample’s quantity, which itself can be based on

various units (volume, weight, etc.). Hence, before selecting a suitable (set of) method(s), the question(s)

to be answered and properties to be measured need to be specified carefully. This applies not only

to detection methods but also to the sampling and processing/preparation methods associated with

them, right up to the statistical evaluation of results.

A schematic representation of the interdependencies of microplastics analysis is shown in Figure 1. As

a rule, the objective or objectives of a measurement or a measurement program is/ are based on a clear

question/task or on an evaluation concept involving necessary assessment parameters, respectively

(for example integration into an overall ecological context, thresholds for monitoring). A suitable

detection method is then selected, which generates the desired result parameters (such as polymer

type, mass content, number, shape, size, degradation status).

Figure 1 — Schematic representation of interdependencies during microplastics analysis in

environmental and related matrices
5 General requirements for all analytical steps

All analytical steps (sampling, sample preparation, detection) shall be undertaken in plastics-free

or low­plastics working conditions. These include the avoidance of standard plastics products (for

example tubes, vessels). Contamination, especially cross-contamination shall be avoided, the user

should avoid using plastics equipment wherever possible. Instead, alternatives made of metal, glass

or ceramics should be used. As an exception and after it was proved by experiments (for example by

characterizing the container), types of plastics that are not to be detected or evaluated can be used as

well. Care should be taken that personal protective equipment (e.g. lab coats, gloves) are also made of

non-synthetic material or material that does not interfere with the analyses. Recovery tests should be

performed for each analytical step.
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ISO/FDIS 24187:2023(E)

If feasible, samples should be handled in laminar flow boxes in the laboratory or clean rooms (class 3

according to ISO 14644-1, especially during the preparation process of samples and during the

determination of particle numbers.

It shall be determined beforehand whether hygienization of samples is necessary. Sterilization is a

standard recommendation for the analysis of dry samples from wastewater, sewage sludge and organic

wastes. Various methods can be applied, but each of them has specific impact on the integrity of

microplastics particles in the sample.
a) Steam sterilization: risk of melting microplastics (for example PE, PP).

b) Radiation sterilization (gamma, beta radiation, UV radiation): risk that the polymer structure is

degraded (cleavage of polymer chains and oxidation).

c) Chemical sterilization: risk that polymer structure or the particles’ surface is chemically modified.

Relevant information about the measurement conditions and control processes (quality assessment

and quality control/QAQC) shall be recorded, including all analytical steps. For general quality control

measures in laboratories, see ISO/IEC 17025:2017. For intercomparison tests, see ISO 13528.

Blank value determination for the applied detection methods is essential, since contamination

(for example by airborne particles) during sampling, preparation and detection can easily occur.

Determination of blank values is essential; the number of blanks depends on the concrete method to be

applied. More specific requirements have to be given in upcoming standards.

A classification of microplastics into size classes according to Table 1 is recommended. Small particles

that occur in higher quantities are grouped into narrower classification classes than the larger particles,

which are more relevant in terms of mass and classified into wider classes. This also enables a higher

methodological feasibility of processes (including feasibility of filtration, detection limits in analytics)

and a better integration of particle quantities/masses in impact analyses (i.e. for environmental

assessments). The proposed size classes are given in Table 1. The maximum dimension/diameter/

length of a particle defines the size class.
Table 1 — Particle size classification
Large mi-
Classification Microplastics
croplastics
particle size 100 to 500 to
μm 1 to < 5 5 to < 10 10 to < 50 50 to < 100 1 000 to 5 000
classes < 500 < 1 000
average par­
μm 3 7,5 30 75 300 750 3 000
ticle size
a −8 −7 −5 −4
mass mg 1,4 × 10 2,2 × 10 1,4 × 10 2,2 × 10 0,014 0,22 14
number of
9 7 6 4
particles in number 1,0 × 10 6,4 × 10 1,0 × 10 6,4 × 10 1 000 64 1
14,13 mg

Mass here is estimated from the average particle size (3 000 µm) assuming spherical particle with a density of 1.

6 Identification of appropriate detection methods
6.1 General

The selection of one or more quantitative or qualitative detection method(s) depends specifically on

the objectives and tasks of a project or an existing requirement. The various detection methods differ

regarding the generated result per measurement. These include identification of the polymer (type of

polymer) and other qualitative properties (i.e. presence of additives, chemical composition, molecular

weight and morphology of particle surface, particle size and shape) and quantitative properties

(particle number, particle mass fraction).
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Depending on the objective of the analysis, it can be sufficient to apply a (pre-)screening method

that may give limited information, but does not require sophisticated instrumentation. For (pre-)

screening purposes relatively simple and inexpensive techniques could be used. Like this, cost-effective

routine analyses can be carried out with a higher throughput than more performance but highly time

consuming and costly techniques.
6.2 Detection techniques

Different detection methods based on various measurement principles are available for microplastics

analysis.

Spectroscopic methods can capture and assign the characteristics of specific chemical structures of

polymers using reference spectra. Used methods are based on vibrational spectroscopy techniques

(including on microscopic level) including different measurement setups:
— Fourier transform infrared spectroscopy (FTIR);

— attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR);

— focal plan array detector Fourier transform infrared spectroscopy (FPA-FTIR);
— quantum cascade laser induced infrared spectroscopy (QCL-IR);
— near or short-wave infrared spectroscopy (NIR, SWIR);
— Raman spectroscopy.

In thermo-analytical methods, the sample is pyrolysed under inert conditions and specific

decomposition products of the individual polymers are detected. Currently well-established are gas

chromatography-mass spectrometry (GC-MS) methods. They differ regarding the heating procedure

(filament based, micro furnace, Curie point), the sample amounts or sample preparation of individual

selected or concentrated particles (pyrolysis - Py-GC-MS) as well as pyrolysis of complete filter residues

(thermal extraction desorption - TED-GC-MS). Further methods are suitable, an alternative is the use of

methods, which detect the specific melting process of semi-crystalline polymer materials (differential

scanning calorimetry, DSC).

Chemical methods are used to decompose the samples and detect specific fragments of polymers or

elements. Examples are inductively coupled plasma mass spectrometry (ICP-MS) for tyre and road

wear particles or liquid chromatography (LC) for PET, PC or PA, respectively.

Further methods are suitable, such as visual sorting of larger items using microscopy or hot needle test

Such visual sorting is subjective and depends on the expertise of the experimenter. An alternative is

also the detection of dyed particles by fluorescence microscopy and spectroscopy. These methods are

(partly) restricted regarding the analytical accuracy of polymeric particles but represent fast screening

solutions.

All the tools differ regarding the preparation of the samples, the maximum number and sizes of

measurable particles or sample mass, the measurement time and the lower detection level regarding

the lateral resolution or limit.
6.3 Identification of objective to be addressed

Mass content is a monitoring parameter used to estimate the occurrence of microplastics. They

are suitable when it comes to the regular, repeated determination of microplastics in the context of

monitoring and the control of the effectiveness of measures against plastics inputs. The nominal range

of particle size for which these detection analyses are to be made shall be defined in advance. This

grouping into size classes (Table 1) makes it possible to assign the total contents to a specific particle

size range. The contents of the different plastics can be measured in a consistent way, regardless of

particle shape, number and size. In principle, it should be taken into account that a few large particles

are more significant in terms of mass balance than many small particles.
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Determining the exact number, size and shape of particles provides a very comprehensive, detailed

picture of the occurrence of microplastics in environmental samples. This is important for toxicological

studies and assessment. The suitability of the measurement technique for the nominal particle size

range to be investigated shall be ensured in advance. For spectroscopic results it is possible to evaluate

the particle size during or after measurement. The particles of the different plastics can thereby be

measured in a consistent way according to particle shape, number and size. Classification into size

classes (see Table 1) allows for comparing the total contents for a specific particle size range. The

analysis of very small particles (<5 μm) is complex and partly limited for real samples. The evaluation

methods shall guarantee homogeneity of the analysed environmental sample aliquots, as often only a

fraction of the sample can be analysed.

The individual characterization of specific properties of identified plastics particles, for example the

state of degradation, the surface structure or condition, and the analysis of additives can be relevant for

evaluating the interaction with the environment, but also for assessing their sources, entry paths, and

fate. Such analyses may require prior, and in some cases very complex, isolation of individual particles.

7 Sampling of water
7.1 General

Determination of microplastics in the various environmental matrices are a relatively new field of

research. In the following, reference is made to
...