Overview
ISO/TS 14411-1:2017 specifies how to prepare polydisperse particulate reference materials built from a “picket fence” of quasi‑monodisperse spherical particles. The Technical Specification sets out the technical specifics for selecting, characterizing and combining monodisperse fractions and for estimating the uncertainty of the resulting mixtures. These picket‑fence materials are intended to support comparability across particle sizing methods within the applicable limits of each technique.
Key topics and requirements
- Material requirements for individual monodisperse fractions (sphericity, homogeneity and general properties).
- Characterization of monodisperse components:
- Particle size distribution (number- and mass-/volume-based)
- Aspect ratio (shape considerations)
- Density (pycnometry, hydrostatic balance references)
- Refractive index
- Preparation procedures for picket‑fence distributions:
- Preparation from dry powders and from suspensions
- Preparation of individual “pickets” and controlled mixing to form polydisperse samples
- Determination of particle mass fractions and sample handling considerations
- Uncertainty estimation for mixtures:
- Uncertainty contributions for count-based and mass-based size distributions
- Effects of limited particle counts, mixture fractions and sampling
- Uncertainty in microscopic measurements (including neighbouring particles)
- Combining multiple uncertainty components into a combined uncertainty
- Informative annexes providing worked examples such as reliability calculations for mass-based cumulative size distribution and multiple‑picket cases.
Applications and who uses it
ISO/TS 14411-1:2017 is directly relevant for:
- Reference material producers preparing certified and non‑certified particulate RMs
- Metrology institutes and calibration laboratories establishing traceability for particle size
- Analytical laboratories validating and verifying particle sizing methods (laser diffraction, microscopy, particle counters, sedimentation techniques)
- Instrument manufacturers seeking benchmark materials to demonstrate method performance and comparability
- Regulatory and quality assurance teams that require robust uncertainty budgets and inter‑method comparability for particle characterization.
Practical uses include method validation, interlaboratory comparisons, instrument performance verification and developing measurement uncertainty estimates for particle size distributions.
Related standards
This TS complements general guidance for reference materials and certification such as ISO Guide 30, ISO Guide 31, ISO Guide 35 and ISO 17034 and references particle‑specific standards (e.g., density and aspect ratio definitions). For full preparation protocols, characterization methods and worked uncertainty examples refer to the full ISO/TS 14411-1:2017 document.