Overview
ISO 13319-2:2023 - "Determination of particle size distribution - Electrical sensing zone method - Part 2: Tunable resistive pulse sensing method" defines how to measure particle size distribution, particle concentration, and zeta potential of particles suspended in liquid using Tunable Resistive Pulse Sensing (TRPS). The standard covers TRPS measurements for particles from 40 nm to 100 µm, describes the underlying principles (electrical sensing zone), and provides methodology, calibration guidance, best practices, common pitfalls and troubleshooting to ensure reproducible and accurate results.
Key technical topics and requirements
- Measurement principle: Particles passing through an aperture cause resistive pulses as conductive electrolyte is displaced; pulse height, width and frequency are used to derive size, concentration and zeta potential.
- Instrumentation: Use of electrodes (Ag/AgCl), voltage source, pressure module, amplifier, ADC and data acquisition software.
- Apertures: Support for both fixed and tunable apertures (notably TPU membranes that can be mechanically stretched) and guidance on aperture preparation, wetting and coating.
- Calibration: Use of calibration standards (or fixed aperture geometries) to achieve traceable and accurate particle diameter and concentration measurements.
- Operational parameters: Control and optimization of pressure, voltage and stretch to manage convective vs electrokinetic transport, dynamic/detection ranges, and to minimize coincidence events and off-axis transport.
- Electrokinetic effects: Consideration of electrophoresis, electroosmosis, polarization, dielectrophoresis, and drag forces that influence single-particle translocation and measurement accuracy.
- Sample preparation and handling: Suspension requirements, contamination prevention, removal of proteins/solutes, and strategies to maintain particle integrity and stability.
- Quality and troubleshooting: Best practice annex, troubleshooting factors, method development guidance and illustrative annexes (e.g., nano-/micro-bubble measurement).
Practical applications and intended users
ISO 13319-2:2023 is relevant for laboratories and organizations that require rigorous nanoparticle and microparticle characterization, including:
- Academic and industrial researchers working on nanomedicine, extracellular vesicles (EVs), liposomes and nano-pharmaceuticals.
- Quality control and R&D teams in pharmaceuticals, biotechnology, materials science, and environmental monitoring.
- Instrument manufacturers and calibration service providers developing or validating TRPS systems and TPS apertures.
- Labs performing particle concentration and size distribution assays that require traceability and reproducibility.
Implementing this standard helps improve measurement consistency, reduce artefacts from electrokinetic effects and provide defensible data for research, regulatory submissions and quality assurance.
Related standards
- ISO 13319-1 (electrical sensing zone fundamentals and schematic reference)
- ISO 13099 (zeta potential / electrophoretic mobility terminology)
- ISO 26824 (electrokinetics terminology)
Keywords: ISO 13319-2:2023, Tunable Resistive Pulse Sensing, TRPS, particle size distribution, particle concentration, zeta potential, electrical sensing zone, TPU aperture, calibration, nanoparticle characterization.