Overview
ISO/TR 20489:2018 - Nanotechnologies - Sample preparation for the characterization of metal and metal-oxide nano-objects in water samples - is a technical report that provides an overview of sample preparation approaches for analytical measurements of metal and metal-oxide nano-objects in surface water and drinking water. It covers stages from sample collection and storage through pre-concentration and size-fractionation, with the goal of supporting reliable characterization of nano-objects such as titanium dioxide (TiO2), zinc oxide (ZnO), silver (Ag) and gold (Au).
Key topics and technical content
- Scope and terms: Definitions for manufactured nanomaterials, nano-objects and relevant measurands; focus on surface water and drinking water matrices.
- Sample collection & storage: Practical guidance referencing ISO 5667 series for sampling design, preservation and handling. Typical container materials include HDPE and borosilicate glass; samples are usually stored at ambient or sub-ambient temperatures (not frozen) and may require stabilizers or antimicrobials.
- Pre-treatment methods: Rationale for removing large particulates and/or concentrating nano-objects prior to analysis. Important caution: pre-treatment can remove nano-objects through adsorption to larger particulates.
- Sedimentation and centrifugation: Use of gravitational sedimentation (simple, suitable for bulk removal of particles > ~5 µm) and centrifugation for differential separation and concentration. Notes on operational parameters (RPM vs g-force) and how settling depends on particle size and density.
- Filtration and size-fractionation: Techniques described include membrane filtration, ultrafiltration (UF), size exclusion chromatography (SEC/GPC) and field-flow fractionation (FFF/Flow FFF) - with summaries of advantages and limitations for each approach.
- Annex and references: Informative annex listing relevant characterization techniques and bibliography referencing ISO/TR 18196:2016 and other literature.
Practical applications and intended users
ISO/TR 20489:2018 is designed to help:
- Environmental laboratories and analytical chemists preparing water samples for nanoparticle characterization.
- Water utilities and drinking-water laboratories assessing potential nano-objects after treatment.
- Regulatory bodies and environmental monitoring programs developing sampling protocols for nanoparticle occurrence and fate.
- Researchers and industry stakeholders (nanomaterial manufacturers, product testing labs) seeking harmonized pre-analysis practices prior to techniques like DLS, TEM, ICP-MS or FFF-coupled analysis.
Related standards and guidance
- ISO 5667 series (water sampling design, preservation and handling)
- ISO/TR 18196:2016 (detection/characterization methods for nano-objects in water)
- ISO/TS 80004 series (nanotechnology terminology)
ISO/TR 20489:2018 is a pragmatic reference to improve comparability of nanoparticle measurements in aquatic matrices and to inform development of future standardized methods for metal and metal-oxide nano-object analysis.