ISO/FDIS 16094-3

• Abstract:

  This document sets out key principles for the investigation of microplastics using thermo-analytical methods in water with low content of natural suspended solids. This document gives requirements for the standardisation of methods towards harmonized procedures for determination of microplastics contents.

• Status: Not Published
• ICS: 13.060.45 - Examination of water in general
• Technical Committee: ISO/TC 147/SC 2 - Physical, chemical and biochemical methods
• Drafting Committee: ISO/TC 147/SC 2 - Physical, chemical and biochemical methods
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 15-Sep-2026
• Completion Date: 15-Sep-2026

• Consolidates: FprEN ISO 16094-3 - Water quality - Analysis of microplastic in water - Part 3: Thermo-analytical methods for waters with low content of suspended solids including drinking water (ISO/FDIS 16094-3:2026)
• Effective Date: 12-Feb-2026

Overview

ISO/FDIS 16094-3:2026 defines key principles and standardized procedures for the analysis of microplastics in water, with an emphasis on waters with low natural suspended solids, including drinking water. This international standard, developed by ISO Technical Committee 147 (Water quality) in collaboration with related committees, focuses on thermo-analytical methods such as thermal extraction/desorption gas chromatography-mass spectrometry (TED-GC-MS) and pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) for detecting microplastics.

Standardizing analytical techniques for microplastic analysis is crucial for harmonized data collection, comparability, and reliable environmental and health risk assessments. This standard outlines procedures to identify and quantify the mass and types of microplastic polymers in water samples, promoting consistency and improved reproducibility in laboratory practice.

Key Topics

• Thermo-analytical Methods: Covers the application of TED-GC-MS and Py-GC-MS to identify the chemical nature and mass of microplastics in water samples, including the preparation, detection, and quantification steps.
• Sample Handling and Preparation: Stipulates filtration, drying, homogenization, and required cleaning protocols to prevent contamination and ensure data reliability.
• Laboratory Precautions: Recommends minimizing plastic use in the laboratory environment and details decontamination routines for equipment and materials.
• Contamination Control: Highlights the importance of field blanks and blank tests, ensuring contamination is detected and accounted for in results.
• Polymer Types Identifiable: Focus on industrially common and environmentally prevalent polymers such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and polystyrene (PS), with the inclusion of additional polymers based on method capabilities.
• Calibration Materials: Details the use of suitable polymer calibration materials and the role of internal standards in result validation.
• Limitations: This standard is not intended for determining microplastic particle size, shape, or number in samples.

Applications

ISO/FDIS 16094-3 is highly relevant in the following areas:

• Drinking Water Quality Monitoring: Ensures reliable microplastic detection in treated and natural drinking water supplies through harmonized analytical practice, supporting public health protection.
• Environmental Assessment: Supports regulatory agencies and environmental laboratories in routinely monitoring microplastic contamination in rivers, lakes, groundwater, and other low-turbidity water sources.
• Research & Development: Provides standardized methods for academic and industrial researchers investigating the prevalence and sources of microplastics in aquatic environments.
• Quality Assurance in Laboratories: Offers detailed protocols supporting quality management systems and accreditation for laboratories engaged in microplastic analysis.
• Policy and Compliance: Assists governmental bodies and private sector stakeholders in meeting environmental directives and reporting obligations concerning microplastic pollution.

Related Standards

For comprehensive assessment of microplastics and water quality, the following standards are particularly relevant:

• ISO 16094-2: Water quality – Analysis of microplastic in water – Part 2: Spectroscopic techniques. Complements this standard by covering other analytical methods.
• ISO 14644-1: Cleanrooms and associated controlled environments – Part 1: Cleanliness classification, referenced for laboratory environment specifications.
• ISO 6107 and ISO 5667-27: Provide guidance on sampling terminology and procedures in water quality contexts.
• ISO 11358-1: Details reference procedures for TED-GC-MS in polymer analysis.
• ISO 472 and ISO/TR 21960: Contain terminology and definitions related to plastics and microplastics.

In summary, ISO/FDIS 16094-3:2026 provides practical, standardized guidance for the reliable and consistent analysis of microplastics in water with low suspended solids, enhancing the capacity for meaningful water quality monitoring and environmental protection initiatives.

FINAL DRAFT
International
Standard
ISO/TC 147/SC 2
Water quality — Analysis of
Secretariat: DIN
microplastic in water —
Voting begins on:
2026-09-15
Part 3:
Thermo-analytical methods
Voting terminates on:
2026-11-10
for waters with low content
of suspended solids including
drinking water
Qualité de l'eau — Analyse des microplastiques dans l'eau —
Partie 3: Méthodes thermo-analytiques pour les eaux à faible
teneur en matières en suspension, y compris l'eau potable
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
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/CEN PARALLEL PROCESSING 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.
Reference number
FINAL DRAFT
International
Standard
ISO/TC 147/SC 2
Water quality — Analysis of
Secretariat: DIN
microplastic in water —
Voting begins on:
Part 3:
Thermo-analytical methods
Voting terminates on:
for waters with low content
of suspended solids including
drinking water
Qualité de l'eau — Analyse des microplastiques dans l'eau —
Partie 3: Méthodes thermo-analytiques pour les eaux à faible
teneur en matières en suspension, y compris l'eau potable
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.
© ISO 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/CEN PARALLEL PROCESSING
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be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 3
5 Principle of thermoanalytical techniques . 4
6 Materials . 5
6.1 Reagents and consumables .5
6.2 Plastic calibration material .5
7 Precautions for laboratory environment, apparatus and materials . 5
7.1 Operating precautions for laboratory environment .5
7.2 Cleaning protocol for materials and equipment .6
8 Handling of samples before analysis . 6
8.1 Filtration .6
8.2 Drying of filtration residues .6
8.3 Homogenization of filtration residues .7
9 Procedure . 7
9.1 General .7
9.2 Investigations of filtration residues from water using TED-GC-MS (method 1) .8
9.2.1 Procedure .8
9.2.2 Identification .8
9.2.3 Quantification .9
9.2.4 Quality assessment and control .10
9.2.5 Limitations and further aspects using this method .11
9.3 Investigations of filtration residues from water using Py-GC-MS (method 2) .11
9.3.1 Procedure .11
9.3.2 Identification . 12
9.3.3 Quantification . 13
9.3.4 Quality assessment and control .14
9.3.5 Limitations and further aspects using this method .14
9.4 Investigation of isolated particles using Py-GC-MS (method 3) .14
9.4.1 Procedure .14
9.4.2 Identification . 15
9.4.3 Quantification . 15
9.4.4 Limitations and further aspects using this method . 15
10 Test report .15
Annex A (informative) Exemplary LOD and LOQ values . 17
Annex B (informative) Performance data . 19
Annex C (informative) Overview about the conditions used in ILT .20
Bibliography .23

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 147, Water quality, Subcommittee SC 2,
Physical, chemical and biochemical methods, in collaboration with Technical Committee ISO/TC 61, Plastics,
Subcommittee SC 14, Environmental aspects, andin collaboration with the European Committee for
Standardization (CEN) Technical Committee CEN/TC 230, Water analysis, in accordance with the Agreement
on technical cooperation between ISO and CEN (Vienna Agreement).
A list of all parts in the ISO 16094 series can be found on the ISO website.
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
Pollution linked to microplastics is recognized as a global phenomenon. The standardization of the sampling,
quantification and identification protocols is required to ensure reliability and comparability of the data
produced for health and environmental risk assessments.
Microplastics in water can be identified and quantified using various methodological approaches.
Depending on the measurement objectives, several complementary approaches can be used to cover the
full spectrum of microplastics (size and chemical nature). Table 1 summarizes the characteristics and the
information obtained with the thermo-analytical technics. ISO 16094-2 is applicable for the determination
of microplastic with spectroscopic techniques.
Table 1 — Characteristics of the various analytical techniques and information obtained
TED-GC-MS Py-GC-MS
Characteristics and
Investigations of filtration Investigations of filtration Investigation of isolated particles
information obtained
residues from water (Method residues from water (Method (Method 3)
1) 2)
Type of sample Water filtration residue / particles Isolated particles
Chemical nature of the
Yes
polymer
Information provided
Thermal decomposition products
by analytical technique
Results expression Polymer type, mass Polymer type
Minimum measurable
NA Visual identification
size of particles
Minimum mass subject
to measurement after 0,1 mg up to 2 mg (absolute) 0,01 mg up to 1 mg (absolute) NA
preparation
Key
TED-GC-MS thermal extraction and desorption - gas chromatography - mass spectrometry
Py-GC-MS pyrolysis - gas chromatography - mass spectrometry
NA  not applicable
v
FINAL DRAFT International Standard ISO/FDIS 16094-3:2026(en)
Water quality — Analysis of microplastic in water —
Part 3:
Thermo-analytical methods for waters with low content of
suspended solids including drinking water
WARNING — 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.
IMPORTANT — Tests conducted according to this document shall be carried out by suitably trained
staff.
1 Scope
This document provides the key principles for the analysis of microplastics in drinking water and water
with low content of natural suspended solids using thermo-analytical methods.
This document covers the determination of polymer types and the mass of microplastics in the sample.
This document is not applicable for the determination of particle size, particle shape and particle numbers.
This document is applicable for the detection of microplastics in drinking water and waters with low content
1)
of natural total suspended solids (TSS) .
The described detection procedures are suitable for various types of samples.
NOTE In cases where this document is used for the detection of microplastics in water with TSS contents
higher than those defined here, laboratories commonly include additional quality assessment and control measures
(including preparation) to evaluate whether the detection methods perform adequately for increased amounts of TSS.
This document describes the detection of different types of polymers, [the most used ones in the industry
and the most abundant ones in the environment being polyethylene (PE), polypropylene (PP), polyethylene
terephthalate (PET) and polystyrene (PS), which are analysed by thermo-analytical methods]. Depending
on the used thermo-analytic methods, additional further polymer can be detected, such as polyvinylchloride
(PVC), polycarbonate (PC), poly-methylmethacrylate (PMMA) polyamides (PA), polyurethanes (PU), as well
2)
as signals from PS-co-polymers .
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.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
1) ISO 6107 or ISO 5667-27 (1 mg/l to 100 mg/l) or lower if they interfere with determination.
2) PS-co-polymers are polymers of styrene, acrylonitrile and butadiene (such as ABS). Signals from PS-co-polymers can
be derivate from tire wear (including SBR) and can be detect with the methods as well, but elastomers are outside the
scope of 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/
3.1
microplastic
solid plastic or synthetic polymer particle insoluble in water with the largest dimension between 1 μm and
5 mm
Note 1 to entry: Microplastics can have various shapes.
Note 2 to entry: This definition encompasses the ISO/TR 21960 definitions of large microplastics and microplastics.
Note 3 to entry: The term “microplastics” covers the sum of several individual microplastic particles.
3.2
pyrolysis
irreversible chemical decomposition of a material due to an increase in temperature without oxidation
[SOURCE: ISO 4880:1997, 53]
3.3
thermal decomposition
process whereby the action of heat or elevated temperature on an item causes changes in the chemical
composition
Note 1 to entry: “Thermal decomposition” is not the same as “thermal degradation”. Thermal degradation is an
irreversible process leading to a significant change in the structure of a material, typically characterized by a change
of properties (e.g. integrity, molecular mass or structure, mechanical strength) and/or by fragmentation, affected by
environmental conditions, proceeding over a period of time and comprising one or more steps [SOURCE: ISO 472:2013,
2.262].
Note 2 to entry: Pyrolysis is a specific type of thermal degradation which takes place in the absence of oxygen.
[SOURCE: ISO 472:2013, 2.1285, modified — Note 1 to entry has been modified and Note 2 to entry has been
added.]
3.4
matrix interference
change in analytical response for a specified analyte, caused by variations in matrix composition
[SOURCE: ISO 15796:2005, 2.10]
3.5
field sample
field condition sample, prepared by sampling personnel for sending to the laboratory, from which a test
sample can be prepared
[SOURCE: ISO 14388-1:2014, 3.22]
3.6
test sample
sample, prepared from the laboratory sample (sample or sub-sample(s) sent to or received by the laboratory),
from which test portions are removed for testing or analysis
[SOURCE: ISO 21268-1:2019, 3.8, modified — "(sample or sub-sample(s) sent to or received by the laboratory)"
has been added to the definition.]
3.7
field blank
test sample obtained according to the field blank procedure

[SOURCE: ISO 12141:2024, 3.13], modified — "sample" has been added to the definition.]
3.8
field blank procedure
procedure used to ensure that no significant contamination has occurred during all the steps of the
measurement
Note 1 to entry: This includes for instance the equipment preparation in laboratory, its transport and installation in
the field as well as the subsequent analytical work in the laboratory.
[SOURCE: ISO 12141:2024, 3.14]
3.9
blank test
test performed without sample in the same manner as, and parallel with, a test using an analytical sample
[SOURCE: ISO 11323:2010, 8.13]
Note 1 to entry: Analytical sample is used synonymous to test sample.
4 Abbreviated terms
ABS acrylonitrile butadiene styrene
CM calibration material
GC-MS gas chromatography – mass spectrometry
GFF glass fibres filters
ILT interlaboratory trial
LOD limit of detection
LOQ limit of quantification
ISTD internal standard
m/z mass-to-charge ratio
PA polyamide (polymer of caprolactam = PA6, polymer of hexamethylenediamine and adipic
acid = PA 66)
PC polycarbonate
PE polyethylene
PET poly(ethylene terephthalate)
PMMA poly(methyl methacrylate)
PP polypropylene
PS polystyrene
PUR-MDI polyurethane, based on methylene diphenyl diisocyanate
PVC poly(vinyl chloride)
Py-GC-MS pyrolysis-gas chromatography – mass spectrometry

SBR styrene butadiene rubber
S/N signal-to-noise ratio
TED-GC-MS thermal extraction and desorption - gas chromatography - mass spectrometry
TMAH tetramethylammonium hydroxide
TPU-MDI thermoplastic polyurethane, based on methylene diphenyl diisocyanate
5 Principle of thermoanalytical techniques
All thermo-analytical techniques described in this document consist of different steps: pyrolysis, transfer
and separation, and detection and quantification. In a first step, the samples are heated up in an inert
atmosphere until decomposition (pyrolysis). In a second step, the resulting decomposition products are
either directly separated on a gas chromatographic column or first selectively adsorbed or desorbed on a
solid-phase material before they are introduced into the chromatographic system. In a third step, polymer-
specific decomposition products are detected and quantified (detection and quantification) by mass
spectrometry. The various techniques available differ in how these three steps are utilized.
This document encompasses thermo-analytical techniques using GC-MS as separation and detection/
quantification step. For microplastics detection, there are mainly two GC-MS-based techniques available:
— TED-GC-MS;
— Py-GC-MS.
In TED-GC-MS, a sample is heated up in a thermobalance (e.g. according to ISO 11358-1) under a continuous
nitrogen gas flow. At the outlet of the oven, a solid phase sorbent is located, collecting a part of the
decomposition products of the sample. After this process the solid phase sorbent is transferred to a thermal
desorption unit, in which the collected decomposition products are remobilized, trapped, re-focused and
then transferred to the GC-MS system. A relatively large sample mass of filtration residues (5 mg to 100 mg)
can be analysed with TED-GC-MS.
In Py-GC-MS, a sample is thermally decomposed at defined temperatures and under inert conditions. The
volatile decomposition products are transferred via a high temperature split injector into a GC-MS system
with optional cryo-trapping.
Using Py-GC-MS, only lower sample masses of filtration residues (<1 mg) can be analysed. Therefore, when
Py-GC-MS is applied, the investigated volume should be adjusted accordingly.
Depending on the load of organic accompanying matrix, an additional sample preparation step can be
analytically useful. However, in case of water samples with very low content of natural organic solids, no
additional sample preparation is needed.
The total mass of microplastics captured on filters shall be related to the total sample mass (i.e. µg/g), when
reporting the microplastics content as a mass fraction. In case of water filtrate samples, the analysed (i.e.
filtered) volume can be used to express the microplastics concentration in terms of mass per volume (i.e.
µg/l).
More detailed descriptions of the techniques and measurement parameters are provided in Clause 9.
A validation ILT for the determination of microplastics particles and mass fraction in water was carried out
and the related performance data is provided in Annex B. The overview about the conditions used in the ILT
is given in Annex C.
6 Materials
6.1 Reagents and consumables
Filters with appropriate pore size according to the definition of microplastics (see 3.1), used for analysis
should be made of inorganic materials (e.g. glass fibre, alumina filters). When prefiltration is included, the
use of filters made of organic materials (e.g. cellulose) or stainless steel are possible. In case a cleaning or
purging detergent solution is needed, the following cleaning and purge solutions are available:
— ultrapure water: prefiltered using an inorganic < 1 μm pore size filter made of inorganic materials;
— ethanol with water in the above-described quality;
— pharmaceutical quality water or water for injections (water for the preparation of medicines for
parenteral administration when water is used as a vehicle and for dissolving or diluting substances or
preparations for parenteral administration).
6.2 Plastic calibration material
For all thermo-analytical methods, polymers (pure reference materials, solved polymers or polymer
powders with inorganic diluents), ideally without significant amounts of additives or fillers are suitable
as reference material (here named as calibration material, CM). Since thermo-analytical methods do not
measure particle size, generally CM can be used in any form. However, homogeneous polymer powders
(<100 µm) that are easy to dose are particularly suitable and prevent size related effects on heat transfer. In
some cases, aged polymers particles can be easier to handle (static charge, cryogenic grinding).
Such CMs are offered as commercial products in the chemical trade or by manufacturers.
However, dealing with environmental samples with a wide variety of possible and unknown polymer
sources, the same decomposition products from one analytical sample can originate from different types
of polymers (including copolymers) or combinations of polymers (including polymer blends, reinforced
materials). This type cannot be identified by further signals or additional sample preparation steps. In these
cases, the results can be used for identification and clustering purposes. Quantification can only be related
to the respective, defined basic pure polymer.
7 Precautions for laboratory environment, apparatus and materials
7.1 Operating precautions for laboratory environment
Since plastic particles are ubiquitous, contamination during sampling and analysis is likely to occur.
Therefore, the determination of field blank procedures and blank tests is of high importance. This is
especially important in the case of very low microplastics content of the sample.
It is recommended, that the space dedicated to the preparation of samples should be plastic-free or
the amount of plastic should be kept to a minimum (e.g. wall fabrics, flooring). Cleaning of the working
environment is essential (e.g. hood, bench) and shall be carried out regularly. Suitable purging detergent
(see 6.1) or wipes (that do not contaminate the working area with additional particles) shall be used. The
work should be carried out in a laminar flow hood (e.g. according to ISO 14644-1). It is recommended to
switch on the fume hood and to let it work for at least 30 min before starting the analysis. Then, the fume
hood shall be shut down before starting the analysis to prevent any particle loss.
In particular, operators shall
— wash hands (including gloves) before initiating the measurement procedure and at each critical step
thereof, particularly after the external washing of the containers and when entering the premises
dedicated to handling samples;
— wear a cotton laboratory coat or, if applicable, a clean antistatic laboratory coat, 100 % cotton textiles
shall be used;
— when possible, avoid wearing protective polypropylene face masks;
— avoid wearing clothing made of synthetic fibres (e.g. fleece jackets, scarfs), personal hygiene or cosmetic
products (e.g. abrasion of nail polish, presence of microplastics in foundations) liable to release
microplastics in the work environment;
— ensure that any equipment or part of the body placed inside the laminar flow hood has undergone a
decontamination step.
The laboratory shall ensure that the sample is protected from any contamination due to the working
environment, particularly during the transport of the sample between the sample preparation and the place
of measurement unit.
7.2 Cleaning protocol for materials and equipment
The use of plastic laboratory equipment in contact with the sample should be kept to a minimum. This
includes containers and covers for sample storage, tubes for filtrations, filter holders or sealings. Where
possible materials made of glass or metal shall be used. Containers where sampling and processing material
will be stored shall be decontaminated for microplastics to reduce cross-contamination.
Special care shall be taken not to contaminate glassware and metal items not to be in contact with samples,
including sample containers, vessels for pyrolysis experiments (i.e. crucibles, vials, quartz tubes or cups).
The following procedures or steps shall be applied to those materials:
— The glass elements should be immersed in a suitable detergent solution with sufficient contact time (e.g.
12 h). Then, rinse the elements with an appropriate product (e.g. 70 % ethanol) and finish the rinsing
with water filtrated using a filter made of inorganic materials with a pore size smaller than 1 µm.
— Utensils containers should be calcined in an oven at a minimum of 480 °C for 2 h or 450 °C for 6 h. This
includes GFF. Containers where sampling and processing material will be stored shall be decontaminated
for microplastics to reduce cross-contamination.
— Quartz wool, used in particular to maintain samples in pyrolysis supports, shall be conditioned
beforehand at a minimum temperature of 500 °C for at least 2 h. Unless the wool is guaranteed to be
plastic free, this shall serve to minimize microplastic contamination in the particularly critical pyrolysis
unit.
— A possibility is also the treatment with open flame (Bunsen burner or similar) for 10 s as a cleaning
protocol, especially when using tweezers in direct contact with microplastics.
— After cleaning, glassware and metal parts shall be stored in glass or metal containers or under a laminar
flow hood. Contamination of particles can be minimized by storing glassware covered with aluminium
foil or in glass Petri dishes.
8 Handling of samples before analysis
8.1 Filtration
Clause 8 describes sample preparation steps of thermo-analytical methods which are mandatory for the
detection of microplastics in drinking water and water with low suspended solids to avoid contamination.
The analysis of water samples usually includes a filtration step to separate solid matter (particles) from the
water. Alternatively, individual particles can be selected visually or under an optical microscope, separated
using tweezers and analysed individually.
8.2 Drying of filtration residues
Thermo-analytical methods analyse solid samples. In the case of microplastics analysis of water, a water
filtration residue using a meaningful sampling tool shall be analysed. Therefore, it is advisable to first dry

the sample to determine a dry weight. Drying is also advantageous to avoid biological growth during longer
storage. The drying process shall continue until the weight of the sample is constant. The duration until the
weight is constant (measured under room conditions at 20 °C, 1 013 hPa (1,013 bar), e.g. ISO 1) depends on
the source of the sample, the chemical composition and the temperature which is applied. Drying shall be
carried out at room temperature up to a maximum of 40 °C, a temperature over 60 °C should be avoided,
since above this temperature conventional plastic types (PE, PP, PS, PET, PA and PVC) exhibit specific
phase transitions (glass transition temperature and melting temperature) that are associated with altered
decomposition mechanisms. With respect to larger amounts of sample material, the use of freeze drying
helps to avoid agglomeration.
Samples or filters with samples shall be weighed using a suitable balance (i.e. analytical balance capable of
weight measurements down to 0,1 mg, accuracy 0,01 mg or better).
If during sample preparation the sample is turned into a very dry, powdery item, the effect of static charge
can become a problem. This can lead to the loss of microplastics. It shall be decided on a case-by-case basis
whether appropriate wetting with moisture or solvents or the use of appropriate anti-static devices reduces
the problem in the handling of samples.
8.3 Homogenization of filtration residues
The preparation of the dry field sample to a laboratory sample can initially include sufficient homogenization
of the sample. Given that thermo-analytical methods do not detect the particle size distribution, an additional
fragmentation during this step does not affect the result.
When cryogenic milling is performed, the following rules shall be considered:
— Inspection of the cell gasket: If it is damaged, there is a risk of losing a fraction of the sample during
grinding.
— Inspection of the cell gasket post-cryogenic milling to determine if small pieces of plastic material can
have been trapped in seams or sides of cell gasket during milling process.
— Heating of the cell before opening: The cell can be placed for 1 h in an oven at 50 °C. The cell may not be
opened if it is still at temperature below room temperature, as condensation phenomena can appear,
bringing moisture into the sample.
— Opening of the cell in a protected area and transfer of the powder into a new glass bottle (calcined
beforehand).
9 Procedure
9.1 General
Depending on the type of sample or the equipment available, there are three thermo-analytical approaches:
— method 1: investigation of solid filtration residues from water using gas chromatography-mass
spectrometry with TED-GC-MS (see 9.2);
— method 2: investigation of solid filtration residues from water using Py-GC-MS (see 9.3).
Alternatively, a selection of individual particles can be identified visually or under an optical microscope,
using tweezers and directly analysed individually and thermally decomposed under inert conditions in
Py-GC-MS. In this case, also an additional analysis of mass (weighing) and morphology or size (imaging) is
possible, but outside the scope of this document. The analysis of individual particles is also possible using
TED-GC-MS (method 3): investigation of solid filtration individual particles from water isolated particles
using Py-GC-MS (see 9.4).
Using different thermo-analytic methods, the detection of different type of polymers varies: PE, PP, PS
and PET can be analysed with all methods. Depending on the specific thermo-analytical methods used,

additional further polymer can be detected, such as PVC, PC, PMMA, different types of PA, PU and PS-co-
polymers, including SBR.
Internal standards can be added to the test, to validate the result of the method. They are substances that
are not present in the sample but have similar chemical and physical properties as the analytes and undergo
similar interactions with accompanying matrix or surfaces during the test.
EXAMPLE C labelled polymers, deuterated polymers or polymers such as polyfluorostyrene.
9.2 Investigations of filtration residues from water using TED-GC-MS (method 1)
9.2.1 Procedure
Solid samples from sampling (using i.e. fractionated filtration, passive sampling, flow centrifuge) can be
used as powder as received. A drying and homogenization of the samples is recommended. For water with
low content of natural suspended solids, no additional sample preparation is needed.
Solid samples of approximately 5 mg to 100 mg are weighed into the pyrolysis vessels. The exact mass
amount depends on the sample composition (organic or inorganic content) and the microplastics content in
the sample. Alternatively, small filters in the geometry of a pyrolysis vessels with filtration residues from
water can be used directly in agreement with the technical capabilities of the analytical equipment.
As per ISTD C labelled or deuterated polymers can be used. For example, 4 µl of dissolved deuterated
polystyrene (fivefold deuterated aromatic ring) is added to each sample in the pyrolysis vessel (1 mg to
2,5 mg/ml toluene).
9.2.2 Identification
Examples of polymer decomposition products and characteristic marker fragment ions are summarized
in Table 2. Deviations can also occur when microplastics are strongly aged or an interaction during
decomposition with matrix take place.
Table 2 — Examples of detectable polymers, pyrolysis products, characteristic marker fragment
ions using TED-GC-MS of solid water residues
Specific marker fragment ions Marker ion (qualifier) for
Polymer Polymer decomposition product
b
for identification quantification
m/z m/z
1,10-dodecadiene 81, 55, 95, 109
1,11-dodecadiene 81, 55, 95, 109
1,12-tridecadiene 81, 55, 95, 109
a
PE
1,13-tetradecadiene 81, 55, 95, 109 81
1,14-pentadecadiene 81, 55, 95, 109 81
1,15-hexadecadiene 81, 55, 95, 109 81
2,4,6,8-tetramethylundec-10-ene 111, 69, 154, 210 111
PP 2,4,6,8-tetramethylundec-10-ene 111, 69, 154, 210 111
2,4,6,8-tetramethylundec-10-ene 111, 69, 154, 210 111
styrene 104, 78, 51
PS 2,4-diphenyl-1-butene 91, 130, 104, 208 208
2,4,6-triphenyl-1-hexene 91, 117, 207, 194
2-phenylcyclohexene 104, 158, 129, 115 104
SBR
1-phenyl-3,4-divinylcyclohexane /
91, 104, 156, 212
phenyl-[4.4.0]bicyclodecene
a
Results should be cross-checked by use of at least one other diene as quantifier.
b
Results should be cross-checked by an average value of all identification ions.

TTabablele 2 2 ((ccoonnttiinnueuedd))
Specific marker fragment ions Marker ion (qualifier) for
Polymer Polymer decomposition product
b
for identification quantification
m/z m/z
vinyl benzoate 105, 77, 51, 148 105
ethyl benzoate 105, 77, 122, 150 105, 150
PET
benzoic acid 105, 122, 77, 51 105
1,1-biphenyl 154, 76 154
a
Results should be cross-checked by use of at least one other diene as quantifier.
b
Results should be cross-checked by an average value of all identification ions.
9.2.3 Quantification
9.2.3.1 General
The identified peak areas are normalized for the sample mass.
All quantification procedures shall be checked to minimize interferences from matrix by spiking
experiments.
CM shall be available for quantification.
Various methods can be used for determining the mass fraction in the samples. The selection of the different
methods leads to slightly different results and is chosen depending on the number of samples to be analysed
and the available amount of sample mass.
9.2.3.2 Response factors
Based on measurements of defined contents of CM (see 6.2) and their signal intensity, the polymer content in
the analysis sample (S) can be determined. For this certain amounts ( m ) of CM are measured and the peak
areas (A ) of decomposition product compared to those of the sample (A ). The mass m of polymer in the
1 S
S
original sample aliquot is then calculated according to Formula (1):
A
S
mm (1)
S 1
A
For the quantification using response factors, the measurements of CM shall be repeated three times. The
sample only has to be measured twice.
In this way, high number of samples with limited individual sample mass can be analysed, but influence of
the matrix on the analytical result is not considered. Errors can arise from matrix interference.
9.2.3.3 Standard addition
After identifying relevant markers in a test sample (S), defined contents of CM are added in a second
measurement and the signal intensity in the original sample is related to the mass fraction in the spiked
sample. For this, sample aliquots are spiked with a certain amount ( m ) of CM, measured again and the peak
areas ( A ) of decomposition product compared to those of the unspiked sample aliquots ( A ). The mass m
1 S S
of polymer in the original sample aliquot is then calculated according to Formula (2):
A
S
mm (2)
S 1
AA
1 S
For the quantification using standard addition, the neat sample and the spiked sample shall be measured
twice.
In this way, a low number of samples can be analysed and a sufficient amount of sample is necessary for
each. However, due to the inclusion of the matrix, a result with high analytical accuracy can be expected.
9.2.3.4 Matrix related response factors
For a set of samples (S1, S2, S3, etc.) with similar matrix composition, a solid compromise between measuring
effort and result accuracy can be achieved using the following protocol: after identification of relevant
markers, defined contents of CM are added for a second measurement to a single sample (S1) of the sample
set. For this sample aliquots are spiked with a certain amount ( m ) of CM, measured again and the peak
areas ( A ) of decomposition product compared to those of the unspiked sample aliquots (A ). The mass
1 S 1
m of polymer in the original sample aliquot is then calculated according to Formula (3):
S 1
A
S1
mm (3)
S1 1
AA
1 S1
The determined mass fraction m of the signal A can be related to further samples of this set (S2, S3,
S1 S1
etc.) according to Formula (4):
A
S2
mm (4)
S2 S1
A
S1
The selected sample S1 shall have very high homogeneity, be representative for the sample set and be used
in the same amount as in the first measurement. The measurement of the spiked sample shall be performed
shortly after the measurements of the raw samples.
For the quantification using matrix related response factors, the spiked sample (S1) shall be measured
twice, the sample of the sets (S2, S3, etc.) needs only to be measured once.
In this way, a high number of samples can be analysed and measurements also for small sample masses
are realizable (as long as there is enough of at least one sample). Due to the measurement of at least one
(representative) sample, a result with acceptable analytical accuracy can be expected.
For the weighing of CM an ultra-micro balance (readability 0,00 1 mg, repeatability 0,00 25 mg) shall be
used. The amount of added CM depends on the observed signals of samples and should range in the area of
0,01 mg to 0,4 mg. If possible, dissolved polymers in
...

ISO/TC 147/SC 2/JWG 1
Secretariat: DIN
Date: 2026-08-31
Water quality — Analysis of microplastic in water —
—
Part 3:
Thermo-analytical methods for waters with low content of
suspended solids including drinking water
First edition
2026-05-13
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ISO #####-#:####(X)
Qualité de l'eau — Analyse des microplastiques dans l'eau —
Partie 3: Méthodes thermo-analytiques pour les eaux à faible teneur en matières en suspension, y compris l'eau
potable
FDIS stage
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2 © ISO #### – All rights reserved

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
EmailE-mail: [e-mail]
Website: www.iso.org
Published in Switzerland
iii
ISO #####-#:####(X/FDIS 16094-3:2026(en)
Contents
Foreword . v
Introduction . vi
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
4 Abbreviated terms . 3
5 Principle of thermoanalytical techniques. 4
6 Materials . 5
6.1 Reagents and consumables . 5
6.2 Plastic calibration material . 5
7 Precautions for laboratory environment, apparatus and materials . 6
7.1 Operating precautions for laboratory environment . 6
7.2 Cleaning protocol for materials and equipment . 6
8 Handling of samples before analysis . 7
8.1 Filtration . 7
8.2 Drying of filtration residues . 7
8.3 Homogenization of filtration residues . 8
9 Procedure . 8
9.1 General. 8
9.2 Investigations of filtration residues from water using TED-GC-MS (method 1) . 9
9.3 Investigations of filtration residues from water using Py-GC-MS (method 2) . 12
9.4 Investigation of isolated particles using Py-GC-MS (method 3) . 16
10 Test report . 17
Annex A (informative) Exemplary LOD and LOQ values . 19
Annex B (informative) Performance data . 21
Annex C (informative) Overview about the conditions used in ILT . 23
Bibliography . 27

© ISO #### 2026 – All rights reserved
iv
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 documentsdocument 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 147, Water quality, Subcommittee SC 2,
Physical, chemical and biochemical methods., in collaboration with Technical Committee ISO/TC 61, Plastics,
Subcommittee SC 14, Environmental aspects, andin collaboration with the European Committee for
Standardization (CEN) Technical Committee CEN/TC 230, Water analysis, in accordance with the Agreement
on technical cooperation between ISO and CEN (Vienna Agreement).
A list of all parts in the ISO 16094 series can be found on the ISO website.
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.
v
ISO #####-#:####(X/FDIS 16094-3:2026(en)
Introduction
Pollution linked to microplastics is recognized as a global phenomenon. The standardization of the sampling,
quantification and identification protocols is required to ensure reliability and comparability of the data
produced for health and environmental risk assessments.
Microplastics in water can be identified and quantified using various methodological approaches. Depending
on the measurement objectives, several complementary approaches can be used to cover the full spectrum of
microplastics (size and chemical nature). Table 1 Table 1 summarizes the characteristics and the information
obtained with the thermo-analytical technics. ISO 16094-2 is applicable for the determination of microplastic
with spectroscopic techniques.
Table 1 — Characteristics of the various analytical techniques and information obtained
Thermal extraction and
desorption Pyrolysis
associated with gas associated with gas chromatography - mass
Characteristics
chromatography - mass spectrometryPy-GC-MS
and information
spectrometryTED-GC-MS
obtained
Investigations of filtration Investigations of filtration Investigation of isolated particles
residues from water using TED- residues from water using Py- using Py-GC-MS (Method 3)
GC-MS (Method 1) GC-MS (Method 2)
Type of sample Water filtration residue / particles Isolated particles
Chemical nature of the
Yes
polymer
Information provided by
Thermal decomposition products
analytical technique
Results expression Polymer type, mass Polymer type
Minimum measurable
Undefined / not applicableNA Visual identification
size of particles
Minimum mass subject
to measurement after 0,1 mg up to 2 mg (absolute) 0,01 mg up to 1 mg (absolute) N.A.NA
preparation
Key
TED-GC-MS thermal extraction and desorption - gas chromatography - mass spectrometry
Py-GC-MS pyrolysis - gas chromatography - mass spectrometry
NA  not applicable
© ISO #### 2026 – All rights reserved
vi
Water quality — Analysis of microplasticsmicroplastic in water —
—
Part 3:
Thermo-analytical methods for waters with low content of suspended
solids including drinking water
WARNING — 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.
IMPORTANT — It is absolutely essential that testsTests conducted in accordance withaccording to this
document shall be carried out by suitably qualifiedtrained staff.
1 Scope
This document provides the key principles for the analysis of microplastics in drinking water and water with
low content of natural suspended solids using thermo-analytical methods.
This document is applicable forcovers the determination of polymer types of polymers and the mass of
microplastics in the sample.
This document is not applicable for the determination of particle size, particle shape and particle numbers.
This document is applicable for the detection of microplastics in drinking water and waters with low content
1)
of natural total suspended solids (TSS). .
NOTE However, theThe described detection procedures can also be applied to other sorts of are
suitable for various types of samples. Whenever a laboratory applies
NOTE In cases where this document is used for the detection of microplastics in water with higherTSS contents of
TSShigher than those defined here, laboratories commonly include additional quality assessment and control measures
(including preparation) is recommended to be applied to verify thatevaluate whether the detection methods are also
applicableperform adequately for higherincreased amounts of TSS.
This document describes the detection of different typetypes of polymers, which are [the main ones (most
used ones in the industry and the most abundant ones in the environment) being: polyethylene (PE),
polypropylene (PP), polyethylene terephthalate (PET),) and polystyrene (PS). These types of polymers can be
analyzed), which are analysed by all thermo-analytical methods.]. Depending on the used thermo-analytic
methods, additional further polymer can be detected, such as polyvinylchloride (PVC), polycarbonate (PC),
poly-methylmethacrylate (PMMA) polyamides (PA), polyurethanes (PU) and), as well as signals from PS-co-
2)
polymers. .
1)
ISO 6107 or ISO 5667-27 (1 mg/l to 100 mg/l) or lower if they interfere with determination.

2)
PS-co-polymers are polymers of styrene, acrylonitrile and butadiene (such as ABS). Signals from PS-co-polymers can
be derivate from tire wear (including SBR) and can be detect with the methods as well, but elastomers are outside the
scope of this document.
ISO #####-#:####(X/FDIS 16094-3:2026(en)
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 14644-1, Cleanrooms and associated controlled environments — Part 1: Classification of air cleanliness by
particle concentration
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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 3.1
microplastic
solid plastic or synthetic polymer particle insoluble in water with the largest dimension between 1 μm and
5 mm
Note 1 to entry: Microplastics can showhave various shapes.
Note 2 to entry: This definition encompasses the ISO/TR 21960 [11] definitions of large microplastics and microplastics.
Note 3 to entry: The term “microplastics” covers the sum of several individual microplastic particles.
3.2 3.2
pyrolysis
irreversible chemical decomposition of a material due to an increase in temperature without oxidation
[SOURCE: ISO 4880:1997, 53]
3.3
thermal decomposition
process whereby the action of heat or elevated temperature on an item causes changes in the chemical
composition
3.3
Note 1 to entry: “Thermal decomposition” is not the same as “thermal degradation”. Thermal degradation is an
irreversible process leading to a significant change in the structure of a material, typically characterized by a change of
properties (e.g. integrity, molecular mass or structure, mechanical strength) and/or by fragmentation, affected by
environmental conditions, proceeding over a period of time and comprising one or more steps [SOURCE: ISO 472:2013,
2.262].
[SOURCE: ISO 472:2013, 2.262]
3.31.1 3.4
thermal decomposition
process whereby the action of heat or elevated temperature on an item causes changes in the chemical
composition
Note 1 2 to entry: “Thermal decomposition” is not the same as “thermal degradation”.
© ISO #### 2026 – All rights reserved
Note 2 to entry: Pyrolysis is a specific type of thermal degradation which takes place in the absence of oxygen.
[SOURCE: ISO 472:2013, 2.1285], modified — Note 1 to entry has been modified and Note 2 to entry has been
added.]
3.4 3.5
matrix interference
change in analytical response for a specified analyte, caused by variations in matrix composition
[SOURCE: ISO 15796:2005, 2.10]
3.5 3.6
field sample
field condition sample, prepared by sampling personnel for sending to the laboratory, from which a test
sample can be prepared
[SOURCE: ISO 14388-1:2014(en),, 3.22]
3.6 3.7
test sample
sample, prepared from the laboratory sample (sample or sub-sample(s) sent to or received by the laboratory),
from which test portions are removed for testing or analysis
[SOURCE: ISO 21268-1:2019(en), 3.8], 3.8, modified — "(sample or sub-sample(s) sent to or received by the
laboratory)" has been added to the definition.]
3.7 3.8
field blank
test sample obtained according to the field blank procedure
[SOURCE: ISO 12141:2024(en), 3.8]13], modified — "sample" has been added to the definition.]
3.8 3.9
field blank procedure
procedure used to ensure that no significant contamination has occurred during all the steps of the
measurement
Note 1 to entry: This includes for instance the equipment preparation in laboratory, its transport and installation in the
field as well as the subsequent analytical work in the laboratory.
[SOURCE: ISO 12141:2024(en), 3.14]
3.9 3.10
blank test
test performed without sample in the same manner as, and parallel with, a test using an analytical sample
[SOURCE: ISO 11323:2010(en),, 8.13]
Note 1 to entry: Analytical sample is used synonymous to test sample.
4 Abbreviated terms
ABS acrylonitrile butadiene styrene
CM calibration material
ISO #####-#:####(X/FDIS 16094-3:2026(en)
GC-MS gas chromatography – mass spectrometry
GFF glass fibres filters
ILT interlaboratory trial
LOD limit of detection
LOQ limit of quantification
ISTD internal standard
m/z mass-to-charge ratio
PA polyamide (polymer of caprolactam = = PA6, polymer of hexamethylenediamine and adipic
acid = = PA 66)
PC polycarbonate
PE polyethylene
PET poly(ethylene terephthalate)
PMMA poly(methyl methacrylate)
PP polypropylene
PS polystyrene
PUR-MDI polyurethane, based on methylene diphenyl diisocyanate
PVC poly(vinyl chloride)
Py-GC-MS pyrolysis-gas chromatography – mass spectrometry
SBR styrene butadiene rubber
S/N signal-to-noise ratio
TED-GC-MS thermal extraction and desorption- - gas chromatography –- mass spectrometry
TMAH tetramethylammonium hydroxide
TPU-MDI thermoplastic polyurethane, based on methylene diphenyl diisocyanate
5 Principle of thermoanalytical techniques
All thermo-analytical techniques described in this document consist of different steps: pyrolysis, transfer/ and
separation, and detection/ and quantification. In a first step, the samples are heated up in an inert atmosphere
until decomposition (pyrolysis). In a second step, the resulting decomposition products are either directly
separated on a gas chromatographic column or first selectively adsorbed/ or desorbed on a solid-phase
material before they are introduced into the chromatographic system. In a third step, polymer-specific
decomposition products are detected and quantified (detection/ and quantification) by mass spectrometry.
The various techniques available differ in how these three steps are utilized.
This document encompasses thermo-analytical techniques using gas chromatography/mass spectrometry
(GC-MS)GC-MS as separation and detection/quantification step. For microplastics detection, there are mainly
two GC-MS-based techniques available:
— — thermal extraction and desorption gas chromatography/mass spectrometry (TED-GC-MS).
— — pyrolysis gas chromatography/mass spectrometry (Py-GC-MS).
— TED-GC-MS;
© ISO #### 2026 – All rights reserved
— Py-GC-MS.
In TED-GC-MS, a sample is heated up in a thermobalance (e.g. according to ISO 11358-1) under a continuous
nitrogen gas flow. At the outlet of the oven, a solid phase sorbent is located, collecting a part of the
decomposition products of the sample. After this process the solid phase sorbent is transferred to a thermal
desorption unit, in which the collected decomposition products are remobilized, trapped, re-focused and then
transferred to the GC-MS system. A relatively large sample mass of filtration residues (5 mg to 100 mg) can be
analyzedanalysed with TED-GC-MS.
In Py-GC-MS, a sample is thermally decomposed at defined temperatures and under inert conditions. The
volatile decomposition products are transferred via a high temperature split injector into a GC-MS system with
optional cryo-trapping.
Using Py-GC-MS, only lower sample masses of filtration residues (<1 mg) can be analyzedanalysed. Therefore,
when Py-GC-MS is applied, the investigated volume should be adjusted accordingly.
Depending on the load of organic accompanying matrix, an additional sample preparation step can be
analytically useful. However, in case of water samples with very low content of natural organic solids, no
additional sample preparation is needed.
The total mass of microplastics captured on filters shall be related to the total sample mass (i.e. µg/g), when
reporting the microplastics content as a mass fraction. In case of water filtrate samples, the analyzedanalysed
(i.e. filtered) volume can be used to express the microplastics concentration in terms of mass per volume (i.e.
µg/l).
More detailed descriptions of the techniques and measurement parameters are provided in 9Clause 9.
A validation ILT for the determination of microplastics particles and mass fraction in water was carried out
and the related performance data is provided in Annex B. The overview about the conditions used in the ILT
is given in Annex C.
6 Materials
6.1 Reagents/Consumables and consumables
Filters with appropriate pore size according to the definition of microplastics (see 3.13.1),), used for analysis
should be made of inorganic materials (e.g. glass fibre, alumina filters, etc.).). When prefiltration is included,
the use of filters made of organic materials (e.g. cellulose) or stainless steel are possible. In case a cleaning or
purging detergent solution is needed, the following cleaning and purge solutions are available:
— — Ultrapureultrapure water: prefiltered using an inorganic < < 1 μm pore size filter made of inorganic
materials;
— — Ethanolethanol with water in the above-described quality;
— — Pharmaceuticalpharmaceutical quality water /or water for injections (water for the preparation of
medicines for parenteral administration when water is used as a vehicle and for dissolving or diluting
substances or preparations for parenteral administration).
6.2 Plastic calibration material
For all thermo-analytical methods, polymers (pure reference materials, solved polymers or polymer powders
with inorganic diluents), ideally without significant amounts of additives or fillers are suitable as reference
material (here named as calibration material, CM). Since thermo-analytical methods do not measure particle
size, generally CM can be used in any form. However, homogeneous polymer powders (<100 µm) that are easy
ISO #####-#:####(X/FDIS 16094-3:2026(en)
to dose are particularly suitable and prevent size related effects on heat transfer. In some cases, aged polymers
particles can be easier to handle (static charge, cryogenic grinding).
Such CMs are offered as commercial products in the chemical trade or by manufacturers.
However, dealing with environmental samples with a wide variety of possible and unknown polymer sources,
the same decomposition products from one analytical sample can originate from different types of polymers
(including copolymers) or combinations of polymers (including polymer blends, reinforced materials). This
type cannot be identified by further signals or additional sample preparation steps. In these cases, the results
can be used for identification and clustering purposes. Quantification can only be related to the respective,
defined basic pure polymer.
7 Precautions for laboratory environment, apparatus and materials
7.1 Operating precautions for laboratory environment
Since plastic particles are ubiquitous, contamination during sampling and analysis is likely to occur. Therefore,
the determination of field blank procedures and blank tests is of high importance. This is especially important
in the case of very low microplastics content of the sample.
It is recommended, that the space dedicated to the preparation of samples shallshould be plastic-free or the
amount of plastic should be kept to a minimum (e.g. wall fabrics, flooring). Regular cleaningCleaning of the
working environment is essential (for examplee.g. hood, bench).) and shall be carried out regularly. Suitable
purging detergent (see 6.16.1)) or wipes (that do not contaminate the working area with additional particles)
shall be used. Ideally, theThe work willshould be donecarried out in a laminar flow hood (e.g. according to
ISO 14644-1.). It is recommended to switch on the fume hood and to let it work for at least 30 min before
starting the analysis. Then, the fume hood shall be shut down before starting the analysis to prevent any
particle loss.
In particular, operators shall
— — wash hands (including gloves) before initiating the measurement procedure and at each critical step
thereof, particularly after the external washing of the containers and when entering the premises
dedicated to handling samples.;
— — wear a cotton laboratory coat or, if applicable, a clean antistatic laboratory coat, 100 % cotton textiles
shall be used.;
— — when possible, avoid wearing protective polypropylene face masks.;
— — avoid wearing clothing made of synthetic fibres (e.g. fleece jackets, scarfs), personal hygiene or
cosmetic products (e.g. abrasion of nail polish, presence of microplastics in foundations) liable to release
microplastics in the work environment.;
— — ensure that any equipment or part of the body placed inside the laminar flow hood has undergone a
decontamination step.
The laboratory shall ensure that the sample is protected from any contamination due to the working
environment, particularly during the transport of the sample between the sample preparation and the place
of measurement unit.
7.2 Cleaning protocol for materials and equipment
The use of plastic laboratory equipment in contact with the sample should be kept to a minimum. This includes
containers and covers for sample storage, tubes for filtrations, filter holders or sealings. Where possible
© ISO #### 2026 – All rights reserved
materials made of glass or metal shall be used. Containers where sampling and processing material will be
stored are also required toshall be decontaminated for microplastics to reduce cross-contamination.
Special care shall be taken not to contaminate glassware and metal items not to be in contact with samples,
including sample containers, vessels for pyrolysis experiments (i.e. crucibles, vials, quartz tubes or cups).
The following procedures or steps shall be applied to those materials:
— — The glass elements should be immersed in a suitable detergent solution with sufficient contact time
(e.g. 12 h). Then, rinse the elements with an appropriate product (e.g. 70 % ethanol) and finish the rinsing
with water filtrated using a filter made of inorganic materials with a pore size smaller than 1 µm.
— — Utensils containers should be calcined in an oven at a minimum of 480 °C for 2 h or 450 °C for 6 h. This
includes glass fibre filters (GFF). Containers where sampling and processing material will be stored are
also required toshall be decontaminated for microplastics to reduce cross-contamination.
— — Quartz wool, used in particular to maintain samples in pyrolysis supports, shall be conditioned
beforehand at a minimum temperature of 500 °C for at least 2 h. Unless the wool is guaranteed to be plastic
free, this shall serve to minimize microplastic contamination in the particularly critical pyrolysis unit.
— — A possibility is also the treatment with open flame (Bunsen burner or similar) for 10 seconds s as a
cleaning protocol, especially when using tweezers in direct contact with microplastics.
— — After cleaning, glassware and metal parts shall be stored in glass or metal containers or under a
laminar flow hood. Contamination of particles can be minimized by storing glassware covered with
aluminumaluminium foil or in glass Petri dishes.
8 Handling of samples before analysis
8.1 Filtration
8This clause describes sample preparation steps of thermo-analytical methods which are mandatory for the
detection of microplastics in drinking water and water with low suspended solids to avoid contamination.
The analysis of water samples usually includes a filtration step to separate solid matter (particles) from the
water. Alternatively, individual particles can be selected visually or under an optical microscope, separated
using tweezers and analyzedanalysed individually.
8.2 Drying of filtration residues
Thermo-analytical methods analyzeanalyse solid samples. In the case of microplastics analysis of water, a
water filtration residue using a meaningful sampling tool willshall be analyzedanalysed. Therefore, it is
advisable to first dry the sample to determine a dry weight. Drying is also advantageous to avoid biological
growth during longer storage. The drying process shall continue until the weight of the sample is constant.
The duration until the weight is constant (measured under room conditions at 20 °C, 1013 1 013 hPa
(1,013 bar), e.g. ISO 1) depends on the source of the sample, the chemical composition and the temperature
which is applied. Drying shall be carried out at room temperature up to a maximum of 40 °C, a temperature
over 60 °C should be avoided, since above this temperature conventional plastic types (PE, PP, PS, PET, PA,
and PVC) exhibit specific phase transitions (glass transition temperature, and melting temperature) that are
associated with altered decomposition mechanisms. With respect to larger amounts of sample material, the
use of freeze drying helps to avoid agglomeration.
Samples or filters with samples shall be weighed using a suitable balance (i.e. analytical balance capable of
weight measurements down to 0,1 mg, accuracy 0,01 mg or better).
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If during sample preparation the sample is turned into a very dry, powdery item, the effect of static charge can
become a problem. This can lead to the loss of microplastics. It shall be decided on a case-by-case basis
whether appropriate wetting with moisture or solvents or the use of appropriate anti-static devices reduces
the problem in the handling of samples.
8.3 Homogenization of filtration residues
The preparation of the dry field sample to a laboratory sample can initially include sufficient homogenization
of the sample. BecauseGiven that thermo--analytical methods do not detect the particle size distribution, an
additional fragmentation during this step does not affect the result.
When cryogenic milling is performed, the following rules shall be considered:
— — Inspection of the cell gasket: it is essential to check the condition of the gasket. If it is damaged, there
is a risk of losing a fraction of the sample during grinding.
— — Inspection of the cell gasket post-cryogenic milling to determine if small pieces of plastic material can
have been trapped in seams or sides of cell gasket during milling process.
— — Heating of the cell before opening.: The cell can be placed for 1 h in an oven at 50 °C. The cell may not
be opened if it is still at temperature below room temperature, as condensation phenomena can appear,
bringing moisture into the sample.
— — Opening of the cell in a protected area and transfer of the powder into a new glass bottle (calcined
beforehand).
9 Procedure
9.1 General
Depending on the type of sample or the equipment available, there are three thermo-analytical approaches:
— — Methodmethod 1: Investigationinvestigation of solid filtration residues from water using gas
chromatography-mass spectrometry with thermal extraction and desorption (TED-GC-MS), (see 9.29.2.);
— — Methodmethod 2: Investigationinvestigation of solid filtration residues from water using pyrolysis gas
chromatography-mass spectrometry (Py--GC--MS), (see 9.39.3.).
Alternatively, a selection of individual particles can be identified visually or under an optical microscope, using
tweezers and directly analyzedanalysed individually and thermally decomposed under inert conditions in Py-
GC-MS. In this case, also an additional analysis of mass (weighing) and morphology or size (imaging) is
possible, but outside the scope of this document. The analysis of individual particles is also possible using
TED-GC-MS (method 3): investigation of solid filtration individual particles from water isolated particles using
Py-GC-MS (see 9.4.).
— — Method 3: Investigation of solid filtration individual particles from water isolated particles using
pyrolysis gas chromatography-mass spectrometry (Py-GC-MS), see 9.4.
Using different thermo-analytic methods, the detection of different type of polymers varies: PE, PP, PS, and
PET can be analyzedanalysed with all methods. Depending on the specific thermo-analytical methods used,
additional further polymer can be detected, such as PVC, PC, PMMA, different types of PA, PU and PS-co-
polymers, including SBR.
© ISO #### 2026 – All rights reserved
Internal standards (ISTDs) can be added to the test, to validate the result of the method. They are substances
that are not present in the sample but have similar chemical and physical properties as the analytes, and
undergo similar interactions with accompanying matrix/ or surfaces during the test. Examples of ISTDs are
EXAMPLE C labelled polymers, deuterated polymers, or polymers such as polyfluorostyrene.
9.2 Investigations of filtration residues from water using TED-GC-MS (method 1)
9.2.1 Procedure
Solid samples from sampling (using i.e. fractionated filtration, passive sampling, flow centrifuge) can be used
as powder as received. A drying and homogenization of the samples is recommended. For water with low
content of natural suspended solids, no additional sample preparation is needed.
Solid samples of approximately 5 mg to 100 mg are weighed into the pyrolysis vessels. The exact mass amount
depends on the sample composition (organic/ or inorganic content) and the microplastics content in the
sample. Alternatively, small filters in the geometry of a pyrolysis vessels with filtration residues from water
can be used directly in agreement with the technical capabilities of the analytical equipment.
As per ISTD C labelled or deuterated polymers can be used. For example, 4 µl of dissolved deuterated
polystyrene (fivefold deuterated aromatic ring) is added to each sample in the pyrolysis vessel (1 mg to
2,5 mg/ml toluene).
9.2.2 Identification
Examples of polymer decomposition products and characteristic marker fragment ions are summarized in
Table 2 Table 3. Deviations can also occur when microplastics are strongly aged or an interaction during
decomposition with matrix take place.
Table 32 — Examples of detectable polymers, pyrolysis products, characteristic marker fragment
ions using TED-GC-MS of solid water residues
Polymer decomposition Specific marker fragment Marker ion (qualifier)
Polymer
b
productsproduct ions for identification for quantification
m/z m/z
1,10-dodecadiene 81, 55, 95, 109
1,11-dodecadiene 81, 55, 95, 109
1,12-tridecadiene 81, 55, 95, 109
a
PE
1,13-tetradecadiene 81, 55, 95, 109 81
1,14-pentadecadiene 81, 55, 95, 109 81
1,15-hexadecadiene 81, 55, 95, 109 81
2,4,6,8-tetramethylundec-10-ene 111, 69, 154, 210 111
PP 2,4,6,8-tetramethylundec-10-ene 111, 69, 154, 210 111
2,4,6,8-tetramethylundec-10-ene 111, 69, 154, 210 111
styrene 104, 78, 51
PS 2,4-diphenyl-1-butene 91, 130, 104, 208 208
2,4,6-triphenyl-1-hexene 91, 117, 207, 194
SBR 2-phenylcyclohexene 104, 158, 129, 115 104
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Polymer decomposition Specific marker fragment Marker ion (qualifier)
Polymer
b
productsproduct ions for identification for quantification
m/z m/z
1-phenyl-3,4-divinylcyclohexane /
91, 104, 156, 212
phenyl-[4.4.0]bicyclodecene
vinyl benzoate 105, 77, 51, 148 105
ethyl benzoate 105, 77, 122, 150 105, 150
PET
benzoic acid 105, 122, 77, 51 105
1,1-biphenyl 154, 76 154
a Results should be cross-checked by use of at least one other diene as quantifier.
b Results should be cross-checked by an average value of all identification ions.
9.2.3 Quantification
9.2.3.1 General
The identified peak areas are normalized for the sample mass.
All quantification procedures shall be checked to minimize interferences from matrix by spiking experiments.
CM shall be available for quantification.
Various methods can be used for determining the mass fraction in the samples. The selection of the different
methods leads to slightly different results and is chosen depending on the number of samples to be
analyzed,analysed and the available amount of sample mass.
9.2.3.19.2.3.2 Response factors
Based on measurements of defined contents of CM (see Error! Reference source not found.6.2)) and their
signal intensity, the polymer content in the analysis sample (S) can be determined. For this certain amounts
()(𝑚 ) of CM are measured and the peak areas (A ) of decomposition product compared to those of the sample
(AS). The mass 𝑚 of polymer in the original sample aliquot is then calculated according to Error! Reference
S
source not found.Formula (1)::
𝐴
S
𝑚 =𝑚 ⋅ (1)
S 1
𝐴
For the quantification using response factors, the measurements of CM shall be repeated three times. The
sample only needshas to be measured twice.
In this way, high number of samples with limited individual sample mass can be analyzedanalysed, but
influence of the matrix on the analytical result is not considered. Errors can arise from matrix interference.
9.2.3.29.2.3.3 Standard addition
After identifying relevant markers in ana test sample (S), defined contents of CM are added in a second
measurement and the signal intensity in the original sample is related to the mass fraction in the spiked
sample. For this, sample aliquots are spiked with a certain amount ()(𝑚 ) of CM, measured again and the peak
areas ()(𝐴 ) of decomposition product compared to those of the unspiked sample aliquots ().(𝐴 ). The mass
1 S
𝑚 of polymer in the original sample aliquot is then calculated according to Error! Reference source not
S
found.Formula (2)::
© ISO #### 2026 – All rights reserved
𝐴
S
𝑚 =𝑚 ⋅ (2)
S 1
𝐴 −𝐴
1 S
For the quantification using standard addition, the neat sample and the spiked sample needs toshall be
measured twice.
In this way, a low number of samples can be analyzedanalysed and a sufficient amount of sample is
needednecessary for each. However, due to the inclusion of the matrix, a result with high analytical accuracy
can be expected.
9.2.3.39.2.3.4 Matrix related response factors
For a set of samples (S1, S2, S3, etc.) with similar matrix composition, a solid compromise between measuring
effort and result accuracy can be achieved using the following protocol:
After after identification of relevant markers, defined contents of CM are added for a second measurement to
a single sample (S1) of the sample set. For this sample aliquots are spiked with a certain amount ()(𝑚 ) of CM,
measured again and the peak areas ()(𝐴 ) of decomposition product compared to those of the unspiked
sample aliquots ().(𝐴 ). The mass 𝑚 of polymer in the original sample aliquot is then calculated according
𝑆1 𝑆1
to Error! Reference source not found.Formula (3)::
(3)
𝐴
S1
𝑚 =𝑚 ⋅ (3)
S1 1
𝐴 −𝐴
1 S1
The determined mass fraction 𝑚 of the signal 𝐴 can be related to further samples of this set (S2, S3, etc).)
S1 S1
according to Error! Reference source not found.Formula (4)::
𝐴
S2
𝑚 =𝑚 ⋅ (4)
S2 S1
𝐴
S1
The selected sample S1 shall have very high homogeneity, be representative for the sample set and be used in
the same amount as in the first measurement. The measurement of the spiked sample shall be performed
shortly after the measurements of the raw samples.
For the quantification using matrix related response factors, the spiked sample (S1) needs toshall be measured
twice, the sample of the sets (S2, S3, etc.) needs only to be measured once.
In this way, a high number of samples can be analyzedanalysed and measurements also for small sample
masses are realizable (as long as there is enough of at least one sample). Due to the measurement of at least
one (representative) sample, a result with acceptable analytical accuracy can be expected.
For the weighing of CM an ultra-micro balance (readability 0,00 1 mg, repeatability 0,00 25 mg) shall be used.
The amount of added CM depends on the observed signals of samples and should range in the area of 0,01 mg
to 0,4 mg. If possible, dissolved polymers in dilution series can be used as an alternative.
9.2.4 Quality assessment and control
Blank test determination of the complete systems shall be carried out before each measurement. This includes
the measurement with an empty pyrolysis vessel, a clean solid phase sorbent and complete GC-MS run.
Determination of recovery rates with at least one CM of the complete analysis system before a series of
analyzes, and in practice performed daily.
Additionally, field blanks with pure water or defined polymer mass fractions in water are requiredshall be
used that mimic the external sampling procedure, e.g. pumping water or spiked waters through the sampling
ISO #####-#:####(X/FDIS 16094-3:2026(en)
set. These field blanks areshall be subsequently processed like a sample, including sample drying and
homogenization.
If larger sample amounts are available, duplicate determination for all original samples is recommended.
Limit of detection (LOD) is the lowest possible concentration at which the method can detect the analyte
within the matrix. LOD describes the lowest concentration that stands out from background noise with a
certain reliability. Using TED-GC-MS for microplastics analysis the LOD values can be calculated based on a
quintuple signal-to-noise (S/N) ratio, or based on the standard deviation results of a sample with low
concentration via LOD = is equal to three times standard deviation (see ISO/TS 13530 [1]).). For TED-GC-MS
the LOQ is calculated as three times the LOD. The LOD can be dependentdepend on the sample matrix, and
should also be determined in the presence of matrix.
Examples of LOD and LOQ for the CM are summarized in Annex AAnnex A.
The evaluation of signals from ISTD can be used for quality control of the measurement. The peak areas of the
identified characteristic sample compound and the internal standard are normalized for their sample masses.
9.2.5 Limitations and further aspects using this method
The determination of PVC is not possible with the use of TED-GC-MS, as no specific decomposition product
(inclusive marker ions) couldcan be identified for this polymer to date that could notcannot also come from
other sample components.
The method cannot be different from pure polymer, copolymer, or polymer blends. Quantification can only be
related
...