ASTM D8402-23

Standard Practice for Development of Microplastic Reference Samples for Calibration and Proficiency Evaluation in All Types of Water Matrices with High to Low Levels of Suspended Solids

SIGNIFICANCE AND USE
5.1 These procedures can be used to generate microplastic particles as a simulation of microplastic particles found in the natural environment. Suitable uses may include evaluation of microplastic detection and imaging methods. Use of reference samples will support estimation of ambient and flux concentrations in drinking water, wastewater and natural environments, investigations of microplastic particle degradation, and ingestion of microplastics by animals in the contexts of food safety and human health risk assessment.
SCOPE
1.1 This practice describes manufacturing methods to create microplastic particles from pellets of common polymers and the preparation of microplastic reference samples for calibration and proficiency evaluation of microplastic collection practices, preparation practices, and identification methods.  
1.2 This practice does not describe methods for controlling or characterizing the shapes of particles. The procedures have been observed to yield irregularly shaped particles, the use of which in many cases will serve to remove the analytical bias inherent with using distinctive manufactured spherical beads. Other procedures should be used if spheres or elongated fibers are desired.  
1.3 This practice does not describe handling procedures for waste generated when executing the procedures described herein. It is the responsibility of the user of this practice to follow applicable laws and regulations when manufacturing and disposing of microplastic particles, and to establish appropriate procedures to minimize the amount of waste generated.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Mar-2023
• ICS: 83.080.01 - Plastics in general
• Technical Committee: D19 - Water
• Drafting Committee: D19.06 - Methods for Analysis for Organic Substances in Water

Relations

• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM D8333-20 - Standard Practice for Preparation of Water Samples with High, Medium, or Low Suspended Solids for Identification and Quantification of Microplastic Particles and Fibers Using Raman Spectroscopy, IR Spectroscopy, or Pyrolysis-GC/MS
• Effective Date: 15-Jul-2020
• Refers: ASTM D883-20 - Standard Terminology Relating to Plastics
• Effective Date: 01-Jan-2020
• Refers: ASTM D883-19c - Standard Terminology Relating to Plastics
• Effective Date: 01-Aug-2019
• Refers: ASTM D883-19a - Standard Terminology Relating to Plastics
• Effective Date: 15-Apr-2019
• Refers: ASTM D883-19 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2019
• Refers: ASTM D883-18a - Standard Terminology Relating to Plastics
• Effective Date: 01-Dec-2018
• Refers: ASTM D883-18 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2018
• Refers: ASTM D883-17 - Standard Terminology Relating to Plastics
• Effective Date: 15-Aug-2017
• Refers: ASTM D5905-98(2013) - Standard Practice for the Preparation of Substitute Wastewater
• Effective Date: 01-Jan-2013
• Refers: ASTM D883-12e1 - Standard Terminology Relating to Plastics
• Effective Date: 15-Nov-2012
• Refers: ASTM D1921-12 - Standard Test Methods for Particle Size (Sieve Analysis) of Plastic Materials
• Effective Date: 01-Aug-2012
• Refers: ASTM D883-11 - Standard Terminology Relating to Plastics
• Effective Date: 15-May-2011
• Refers: ASTM D5905-98(2008) - Standard Practice for the Preparation of Substitute Wastewater
• Effective Date: 15-Jul-2008

Overview

ASTM D8402-23 is an international standard developed by ASTM International, titled “Standard Practice for Development of Microplastic Reference Samples for Calibration and Proficiency Evaluation in All Types of Water Matrices with High to Low Levels of Suspended Solids.” This standard outlines laboratory procedures for generating microplastic particles from common polymers and preparing microplastic reference samples. These reference materials are significant for calibrating analytical methods, supporting proficiency testing, and providing quality assurance in microplastic detection and quantification, especially in water samples containing varying concentrations of suspended solids.

ASTM D8402-23 plays a critical role in strengthening the reliability of environmental monitoring for microplastics in drinking water, wastewater, and natural aquatic environments.

Key Topics

• Generation of Microplastic Particles: The document specifies methods to grind polymer pellets such as PVC, PE, PP, PS, and PET into irregularly-shaped microplastic particles of various sizes, simulating particles found in natural environments.
• Sample Preparation for Calibration: Guidance covers preparing both count-based and mass-based microplastic reference samples to calibrate and assess performance of collection, preparation, and identification methods.
• Applicable Polymer Types: Utilizes common, dye-free, and additive-free polymers to minimize analytical biases.
• Quality Control: Details best practices for documenting reference samples, ensuring transfer efficiency, and addressing sample homogeneity and measurement variability.
• Waste Management and Safety: Emphasizes compliance with local regulations for manufacturing and disposal, and establishing safety and environmental protocols for handling microplastics and laboratory waste.
• Analytical Instrumentation: References equipment and procedures including grinders, sonicators, microscopes, and analytical balances for producing and analyzing microplastic samples.

Applications

ASTM D8402-23 delivers practical value for organizations and laboratories involved in microplastic analysis in water and environmental samples:

• Method Validation and Calibration: Enables laboratories to evaluate and calibrate detection instruments, such as spectroscopy or mass-based analysis systems (e.g., IR, Raman, Pyr-GC/MS), under realistic environmental conditions.
• Proficiency Testing: Facilitates interlaboratory comparisons and proficiency evaluations, thereby supporting harmonized data quality in microplastic monitoring.
• Environmental Monitoring: Supports estimation of microplastic concentrations in varied water matrices-including low to high turbidity environments-by providing standardized reference samples.
• Risk and Degradation Assessments: Assists in investigating microplastic particle degradation, ingestion, and associated food safety and human health risks.
• Regulatory Compliance and Research: Assists compliance with international standards and quality control expectations in research, policy development, and environmental reporting related to microplastics.

Related Standards

ASTM D8402-23 references several key standards essential for microplastics analysis and sample preparation:

• ASTM D883: Terminology Relating to Plastics
• ASTM D1193: Specification for Reagent Water
• ASTM D1921: Test Methods for Particle Size (Sieve Analysis) of Plastic Materials
• ASTM D5905: Practice for Preparation of Substitute Wastewater
• ASTM D8333: Practice for Preparation of Water Samples for Identification and Quantification of Microplastic Particles and Fibers
• ISO 8573-1:2010: Compressed Air - Part 1: Contaminants and Purity Classes

Summary

Deploying ASTM D8402-23 ensures reliable, harmonized, and reproducible production of microplastic reference samples for environmental laboratories worldwide. With increasing attention on microplastic contamination in water, this standard is foundational for supporting regulatory compliance, interlaboratory calibration, and advancing microplastic research across all water matrices.

Relevant keywords: microplastic reference samples, calibration, proficiency testing, environmental water analysis, microplastic contamination, water matrices, laboratory standards, particle preparation, analytical quality assurance, method validation, suspended solids, drinking water, wastewater, polymers, environmental monitoring, quality control, standardization.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D8402 − 23
Standard Practice for
Development of Microplastic Reference Samples for
Calibration and Proficiency Evaluation in All Types of Water
Matrices with High to Low Levels of Suspended Solids
This standard is issued under the fixed designation D8402; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This practice describes manufacturing methods to create
D883 Terminology Relating to Plastics
microplastic particles from pellets of common polymers and
D1193 Specification for Reagent Water
the preparation of microplastic reference samples for calibra-
D1921 Test Methods for Particle Size (Sieve Analysis) of
tion and proficiency evaluation of microplastic collection
Plastic Materials
practices, preparation practices, and identification methods.
D5905 Practice for the Preparation of Substitute Wastewater
1.2 This practice does not describe methods for controlling
D8333 Practice for Preparation of Water Samples with High,
or characterizing the shapes of particles. The procedures have
Medium, or Low Suspended Solids for Identification and
been observed to yield irregularly shaped particles, the use of
Quantification of Microplastic Particles and Fibers Using
which in many cases will serve to remove the analytical bias
Raman Spectroscopy, IR Spectroscopy, or Pyrolysis-
inherent with using distinctive manufactured spherical beads.
GC/MS
Other procedures should be used if spheres or elongated fibers
2.2 ISO Standards:
are desired.
ISO 8573-1:2010 Compressed air — Part 1: Contaminants
1.3 This practice does not describe handling procedures for
and purity classes
waste generated when executing the procedures described
3. Terminology
herein. It is the responsibility of the user of this practice to
3.1 For definitions of terms used in this practice, refer to
follow applicable laws and regulations when manufacturing
Terminology D883.
and disposing of microplastic particles, and to establish appro-
priate procedures to minimize the amount of waste generated.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 glass transition temperature, n—a temperature above
1.4 The values stated in SI units are to be regarded as
which an amorphous material transitions from a relatively
standard. No other units of measurement are included in this
brittle material to a viscous, supercooled liquid.
standard.
3.2.2 microplastic, n—any solid, synthetic organic poly-
1.5 This standard does not purport to address all of the
meric material to which chemical additives or other substances
safety concerns, if any, associated with its use. It is the
may have been added, which are particles <5 mm in their
responsibility of the user of this standard to establish appro-
largest dimension, and fibers no longer than 15 mm in length,
priate safety, health, and environmental practices and deter-
with an aspect ratio of at least 30:1 and <500 μm in its smallest
mine the applicability of regulatory limitations prior to use.
dimension.
1.6 This international standard was developed in accor-
3.2.3 suspended solids, n—includes all matter that is re-
dance with internationally recognized principles on standard-
moved by a 0.45 μm pore size filter.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
4. Summary of Practice
mendations issued by the World Trade Organization Technical
4.1 Polymer pellets are processed in a laboratory grinder
Barriers to Trade (TBT) Committee.
that utilizes a spinning blade to fragment the pellets into
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This practice is under the jurisdiction of ASTM Committee D19 on Water and contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
is the direct responsibility of Subcommittee D19.06 on Methods for Analysis for Standards volume information, refer to the standard’s Document Summary page on
Organic Substances in Water. the ASTM website.
Current edition approved April 1, 2023. Published June 2023. DOI: 10.1520/ Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
D8402-23. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D8402 − 23
powders containing particles of various sizes. This practice plastics are measured in terms of mass on a balance and added
does not describe methods of separation of the mixed-size to a simulated water matrix substitute, for example, Practice
powder into fractions based on size ranges. Test Methods D5905. Measurable amounts of microplastic (>1 mg) are
D1921 describes methods for dry sieve separation of polymers diluted into several liters of simulated water matrices, then split
that could be used to separate the powders described in this into several 1 L reference samples. This approach is typically
practice. If particle fractions under approximately 20 μm in used to prepare reference or proficiency samples for other
diameter are desired, suspension of the particles in liquid common environmental analytes such as organic solvents or
followed by filtration or sedimentation methods may be more asbestos. Even with the homogenization step described in 12.6,
effective than dry sieve separation. uniform microplastic counts may be more difficult to achieve in
split samples compared to other analytes, so assessments of the
4.2 Polymers with a glass transition temperature (T ) below
g
standard deviations of both the microplastic mass/sample
room temperature require a different grinding procedure than
within the batch, as well as the equivalent number of particles
polymers with T above room temperature. Polymers with high
g
per sample, are critical for quality control. Depending on the
T tend to undergo brittle fracture during grinding, while
g
standard deviation, this approach may only be suitable for
polymers with low T tend to be stretched into very elongated
g
order of magnitude assessments of accuracy. In addition, the
structures, and special steps must be taken to grind them
completed reference samples should be analyzed by one or
effectively.
more reference laboratories to determine the true mean value of
4.3 Two grinding procedures are described:
the reference samples. Alternatively, the mean count may be
4.3.1 Procedure A—This method uses a blunt-edged blade determined from all participant labs. Despite the inherent
variability, this approach is capable of generating many more
to fragment brittle polymers with a T above room temperature,
g
such as polystyrene (PS), polyvinyl chloride (PVC), and reference microplastics per batch. As such, it may be a
desirable when creating samples for large numbers of
polyethylene terephthalate (PET).
laboratories, or if environmentally realistic microplastic con-
4.3.2 Procedure B—This method uses liquid nitrogen to
centrations are required in very large water volumes. If
embrittle polymers with T below room temperature, such as
g
shipping 1 L vessels of non-DI water, the procedure must
polyethylene (LDPE, HDPE) and polypropylene (PP). Cryo-
include packing safely with ice and providing any needed
milling or cryo-crushing is the process of cooling or chilling a
shipping documentation. This approach will also yield a more
material and then reducing it into a smaller particle size. While
direct comparison to the results of mass-based methods such as
the use of a specialized cryo-mill may be considered to ensure
Pyr-GC/MS.
production of a wide size distribution of particles in this
procedure, the cooled polymers are coarsely fragmented with a
5. Significance and Use
blunt-edged blade and then fragmented into smaller particles
with a sharp cutting blade.
5.1 These procedures can be used to generate microplastic
particles as a simulation of microplastic particles found in the
4.4 Microplastic reference sample preparation includes two
natural environment. Suitable uses may include evaluation of
approaches, (1) count-based reference samples for % recovery
microplastic detection and imaging methods. Use of reference
and (2) mass-based proficiency samples, which possess some
samples will support estimation of ambient and flux concen-
inherent variability between samples.
trations in drinking water, wastewater and natural
4.4.1 Count-based Microplastics Reference—40 mL vials of
environments, investigations of microplastic particle
DI H O containing 20 to 40 microplastic particles are shipped
degradation, and ingestion of microplastics by animals in the
at room temperature to recipient laboratories to spike their own
contexts of food safety and human health risk assessment.
water matrix samples. Because a lab’s water samples may
already contain microplastics, the reference microplastics for
6. Apparatus
each vial should be documented with saved microscopy
6.1 Glass Sample Jars—Clean glass jars to store polymer
images, so their morphologies can be checked against the
powder. If polymer lids are used, lid composition should be
particles identified by the recipient lab. A 100 % transfer
recorded in case potential contamination is discovered; lids
efficiency of particles to vials should be demonstrated. This
with polymer foam liners should be avoided.
method is best suited to low numbers of reference samples due
to the effort of documenting and transferring individual par-
6.2 Timer—A timer with a resolution of 1 s or less to
ticles. As such, this approach is most applicable to generating
measure time intervals during grinding.
reference samples for one’s own laboratory or partner labora-
6.3 Laboratory Grinder—A spinning blade grinder with
tories. In addition, due to the relatively low numbers of
interchangeable blades and a maximum speed of 20 000 rpm to
microplastics per sample, it will yield the most environmen-
30 000 rpm and output power of approximately 100 W. The
tally realistic concentrations when spiking already collected
blade height within the grinding chamber should be adjustable
samples such as filters or subsamples for analysis, rather than
during grinding. Coffee grinders or other consumer-grade
the original water volumes, which can be orders of magnitude
larger.
4.4.2 Mass-based (Gravimetric) Microplastic Standards—
Cooling times described in this standard were established by tests performed
Gravimetric reference samples are prepared in large batches of
with a specific make and model of grinder – thus, cooling times as stated may vary
simulated water matrices. Bulk quantities of reference micro- with other devices.
D8402 − 23
grinders or mills should be avoided. The following grinder 7.2 Liquid Nitrogen—For causing low T polymers to be-
g
accessories are required: come brittle, which facilitates efficient grinding.
6.3.1 Impact Blade—A blunt-edged blade to break apart
particles by impact. 8. Interferences
6.3.2 Cutting Blade—A blade with sharpened edges.
8.1 The cooling times specified in Procedures A and B
6.3.3 Liquid Nitrogen-tolerant Grinding Chamber—A
depend on the particular grinder used and should be increased
chamber that is specified by the manufacturer to be safe for use
if particles become heated above 40 °C, as measured with the
with liquid nitrogen.
infrared thermometer. Clumped or charred particles indicate
6.3.4 Stainless Steel Spatulas—For dispensing polymer ma-
that longer cooling times are needed.
terials into the grinder, and for transporting powder from the
grinder bowl to glass sample jars.
9. Grinding Procedure A
6.4 Vacuum Cleaner—A vacuum cleaner with a high-
9.1 Install the impact blade on the grinder.
efficiency particulate air (HEPA) filter to remove particle dust
9.2 Fill the grind chamber with approximately 40 mL of
from the grinder and workbench.
pellets of a single polymer type.
6.5 Compressed Air—A source of Class 0 compressed air as
9.3 Grind for 10 s, then pause for 10 s to allow cooling.
defined by ISO 8573-1:2010.
Repeat this cycle five times. While grinding, traverse the blade
6.6 Sonicator—A bath-type ultrasonic cleaner that applies
up and down through the vertical extent of the grind chamber,
frequency of 40 kHz 6 10 kHz. The sonicator is used to clean
applying 8 to 10 traversals per 10 s grind period.
polymer dust from grinder parts and spatulas.
9.4 Before opening the grinder, retract the blade as far as
6.7 Type I Reagent Grade Water—Water conforming to
possible from the bottom of the mixing chamber. Briefly turn
Specification D1193 for use as sonicator bath water.
on the grinder once or twice in this position to dislodge
6.8 Infrared Thermometer—Non-contact thermometer to
particles from blade.
monitor the temperature of polymers during manufacturing.
9.5 Pause for 1 min to allow particles suspended in the air to
6.9 Bin with Tight-fitting Lid—A container to store jars of
settle, then open the grinding chamber.
manufactured microplastics and prevent inadvertent release of
9.6 If an undesirable quantity of large pellets remain, wait
particles.
approximately 10 min for the grinder bowl to cool to within
6.10 Certified clean 40 mL glass vials with sealed caps. If
1 °C of room temperature as measured with the infrared
caps contain polymer seals, the polymer type should be
thermometer, then repeat 9.3 and 9.4.
recorded.
9.7 Use a metal spatula to slowly transfer the ground plastic
6.11 Aluminum foil.
to a glass sample jar.
6.12 Stereo-zoom microscope, with camera and image stor-
9.8 Store the glass sample jar in a sealed containment bin
age capability.
with a tight-fitting lid.
6.13 Fine-tipped, stainless steel tweezers, probe, pin, or
9.9 Remove the grinder blade and grinding bowl from the
equivalent micro-tool.
grinder body.
6.14 Ultrapure H O.
9.10 Use the vacuum to thoroughly remove visible polymer
6.15 Clean glass petri dish bottom.
powder, and optionally use a jet of compressed air to remove
remaining particles that were not removed by vacuuming.
6.16 Analytical balance, with precision and calibration
weights appropriate for the microplastic masses to be weighed
9.11 Ultrasonically clean the blade, bowl, and other detach-
(not required for c
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