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ISO 24187 — Microplastics in Drinking Water Standard

Water quality — Analysis of microplastic in water — Part 2: Vibrational spectroscopy methods for waters with low content of suspended solids including drinking water

ISO
https://www.iso.org/standard/84460.html
  • Open Data: No
  • Access: Read Only

Description

ISO 24187 – Plastics — Determination of microplastics in drinking water and low-turbidity waters

ISO 24187 is an international standard that establishes core principles for the investigation of microplastics in drinking water and other waters with low suspended-solids content, using microscopy coupled with vibrational spectroscopy. The standard is designed to support harmonized identification, sizing, and counting of microplastic particles under controlled analytical conditions.

Access and availability

The ISO 24187 standard is behind a paywall and must be purchased through ISO or accessed via institutional subscriptions. While high-level metadata and summaries are publicly visible, full procedural details, requirements, and figures are not freely accessible, which may limit transparency for users without access.

⚠️ As with all ISO standards, the document emphasizes that:

  • Tests must be conducted by suitably qualified personnel
  • The standard does not cover all safety considerations, and users are responsible for establishing appropriate laboratory safety and health practices

Scope of the protocol

ISO 24187 applies specifically to waters with low organic and suspended solids, as defined in ISO 6107, typically in the range of ~1–100 mg/L or lower where interference occurs. Applicable matrices include:

  • Ultrapure water
  • Water intended for human consumption (drinking water)
  • Raw groundwater

Given the typically very low concentrations of microplastics in these waters, the standard places strong emphasis on contamination control during sample preparation.

Intended analytical objectives

The method is designed to:

  • Determine microplastic particle size, spanning 1 µm to 5,000 µm
  • Count microplastic particles and classify them into size ranges
  • Identify polymer composition, focusing on common industrial polymers, including:
    • Polyethylene (PE)
    • Polypropylene (PP)
    • Polyethylene terephthalate (PET)
    • Polycarbonate (PC)
    • Polystyrene (PS)
    • Polytetrafluoroethylene (PTFE)
    • Polyvinyl chloride (PVC)
    • Polyamide (PA)
    • Polymethyl methacrylate (PMMA)
    • Polyurethane (PU)

The method is optimized for automatic or semi-automatic analysis of large numbers of particles, rather than manual particle-by-particle characterization.

Analytical techniques specific in ISO 24187

ISO 24187 recognizes two primary vibrational spectroscopy approaches applied to water filtrate residues:

Raman micro-spectroscopy

  • Chemical identification: Yes
  • Information provided: Functional groups
  • Results expressed as: Polymer type, particle count, particle size
  • Minimum measurable particle size: ~1–5 µm
  • Sample impact: Non-destructive
  • Key interferences:
    Mineral particles, colored particles, pigments, fluorescence, fatty acids, fatty amides, proteins, biofilm or weathering alterations, carbohydrates produced by microbes

Infrared (FTIR) micro-spectroscopy

  • Chemical identification: Yes
  • Information provided: Functional groups
  • Results expressed as: Polymer type, particle count, particle size
  • Minimum measurable particle size: ~20 µm
  • Sample impact: Non-destructive
  • Key interferences:
    Mineral particles, proteins, biofilms or weathering effects, carbon-black-loaded particles, water presence, carbohydrates generated by microbes

⚠️ The standard does not define a minimum measurable mass after sample preparation.

What the standard does not cover

ISO 24187 explicitly does not apply to:

  • Characterization of substances intentionally added to or adsorbed onto microplastics
  • Determination of microplastic particle shape
  • Detailed assessment of additives, sorbed contaminants, or surface chemistry
  • Nanoplastics outside the optical detection limits of the described techniques

Strengths of ISO 24187

Key strengths of ISO 24187 include:

  • International harmonization of microplastics measurement in drinking water contexts
  • Clear analytical scope, with defined size ranges and polymer targets
  • Compatibility with FTIR and Raman spectroscopy
  • Non-destructive measurement, enabling further analyses if needed
  • Strong QA/QC emphasis, particularly for contamination prevention
  • Regulatory relevance, especially for drinking water monitoring programs

Limitations and considerations of ISO 24187

Important limitations to consider:

  • Narrow matrix applicability: Designed only for low-turbidity waters; not suitable for wastewater, sediments, or biota
  • Limited procedural prescriptiveness: Provides principles rather than an end-to-end operational workflow
  • Paywall access: Full technical detail is not openly available
  • No particle shape characterization, which may be important for ecological or health assessments
  • Detection limits depend on technique, with FTIR generally missing smaller particles detectable by Raman
  • Interference-sensitive, particularly in waters with biofilms, pigments, or mineral particulates

Practical context

ISO 24187 is best viewed as a foundational standard for drinking water and low-solid water monitoring, offering an internationally recognized framework for microplastic identification, counting, and sizing. In practice, it is often most effective when combined with matrix-specific sampling protocols, ASTM methods, and program-level QA/QC guidance, especially for broader environmental or risk-assessment applications.

Official ISO page:
https://www.iso.org/standard/84460.html

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