Foreword

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This document was prepared by Technical Committee ISO/TC 24, Particle characterization including sieving, Subcommittee SC 4, Particle characterization.

This second edition cancels and replaces the first edition ( ISO 13099-2:2012 ), which has been technically revised.

The main changes are as follows:

addition of new terms and definitions;
revision of Figure 3, illustrating instrument configuration;
removal of section on cross-beam optics;
revision of the description of phase analysis light scattering (PALS);
addition of information on cell constant.

A list of all parts in the ISO 13099 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Introduction

Zeta-potential is a parameter that can be used to predict the long-term stability of suspensions and emulsions and to study surface morphology and adsorption on particles and other surfaces in contact with a liquid. Zeta-potential is not a directly measurable parameter. It can be determined using appropriate theoretical models from experimentally determined parameters, such as electrophoretic mobility.

Optical methods, especially electrophoretic light scattering, have been widely used to determine electrophoretic mobility of particles or macromolecules in suspension or in solution. The purpose of this document is to provide methods for measuring electrophoretic mobility using optical means and for calculating zeta-potential.

1 Scope

This document specifies two methods of measurement of the electrophoretic mobility of particles suspended in a liquid: video microscopy and electrophoretic light-scattering.

NOTE Estimation of surface charge and determination of zeta-potential can be achieved from measured electrophoretic mobility using proper theoretical models, which are described in detail in ISO 13099-1 .

2 Normative references

3 Terms, definitions and symbols

3.1 Terms and definitions

3.2 Symbols

4 Principles

5 Microscopic methods

6 Electrophoretic light-scattering (ELS) method

6.1 General

6.2 Cell design

6.3 Reference beam optical arrangement

6.4 Signal processing

6.5 Determination of electrophoretic mobility

7 Calculation of zeta-potential

8 Operational procedures

8.1 Requirements

8.2 Verification

8.3 Sources of measurement error

8.4 Test report

Bibliography