Overview - ISO 13099-3:2014 (Acoustic methods)
ISO 13099-3:2014 is part of the ISO 13099 series on colloidal systems and methods for zeta potential determination. This part focuses on electroacoustic (high‑frequency electrokinetic) phenomena and acoustic methods for measuring electrophoretic mobility in concentrated suspensions (typically > 1 % v/v). The standard describes the principles and instrumentation elements for two primary acoustic techniques: colloid vibration current (CVI) and electric sonic amplitude (ESA). Measured electrophoretic mobility can be converted to zeta potential or used to estimate surface charge using theoretical models detailed in ISO 13099‑1.
Key technical topics and requirements
- Scope and terminology: Definitions for electric double layer, Debye length, Dukhin number, surface conductivity, electrophoretic mobility and other electroacoustic terms (CVI, CVU, ESA, IVI, SEI).
- Principle of measurement: Electroacoustic coupling at MHz frequencies; how ultrasonic fields and electric fields generate measurable currents or pressure amplitudes in dispersions.
- Probe and instrument design elements: Considerations for acoustic probe geometry and electrode layout required for reproducible CVI/ESA measurements.
- Determination of dynamic electrophoretic mobility: Measurement procedures, including methods to subtract ion-generated background electroacoustic signals (ion vibration current).
- Theoretical treatment and zeta calculation: Use of established theories (e.g., O’Brien, Smoluchowski and electroacoustic models) to calculate zeta potential for isolated vs. overlapped double layers, polydisperse concentrates and systems with surface conductivity.
- Operational procedures and quality requirements: Instrument location, sample handling and preparation, sample volume fraction limits, verification protocols (reference materials, repeatability, intermediate precision, trueness) and identification of likely sources of measurement error.
- Informative annexes: Background on electroacoustics and verification of electroacoustic theories.
Practical applications
- Predicting long‑term stability of suspensions and emulsions
- Characterizing surface charge, adsorption and surface morphology of particles in concentrated formulations
- Non‑dilutive analysis of concentrated industrial dispersions used in paints & coatings, ceramics, pharmaceuticals, personal care, nanomaterials and wastewater treatment
- Development and validation of electroacoustic zeta potential instrumentation and internal QC procedures
Who should use this standard
- Analytical and formulation scientists, R&D labs and QC teams working with concentrated colloids
- Instrument manufacturers and test labs implementing electroacoustic zeta potential measurements
- Standards bodies and regulatory assessors referencing robust methods for concentrated dispersions
Related standards
Keywords: ISO 13099-3, zeta potential, electroacoustic methods, colloid vibration current (CVI), electric sonic amplitude (ESA), electrophoretic mobility, concentrated suspensions, acoustic zeta potential.