Introduction

Particle1) sizing in the submicrometer size range is nowadays performed on a routine basis using the dynamic light scattering (DLS) method. The success of the technique is mainly based on the fact that it provides estimates of average size and its distribution in a measurement time of a few minutes, and user-friendly commercial instruments are available. Nevertheless, proper use of the instrument and interpretation of the result require certain precautions.

To this end, ISO 13321 was developed. ISO 13321 provides the procedures necessary to allow determination of the correct particle size using the photon correlation technique. The instruments specified in ISO 13321 are restricted to low particle concentrations in order to avoid disturbances due to multiple scattering. Instruments that seek to minimize this restriction are now available. Therefore, there is a need for an International Standard for the determination of particle size by DLS suitable for a wide concentration range of dispersions that will enable users to obtain good interlaboratory agreement on accuracy and reproducibility.

Several techniques have been developed for DLS2). These techniques can be classified in two ways:

a) by the difference in data analysis (correlation method and frequency analysis method);
b) by the difference in optical set-up (homodyne and heterodyne detection optics).

Instruments are now available with a range of fixed and movable cell options.

Although DLS allows the determination of particle-size distribution, this International Standard is limited to the description of size distribution by means of only two robust descriptors: an average size and a polydispersity index. Many different methods for the calculation of full size distributions are used. However, reproducibility of the different methods of calculation for full distributions is, at present, not good enough to include in an International Standard. Therefore, today, there is no standardized algorithm that may be included in an International Standard.

BS ISO 22412:2008

Particle size analysis. Dynamic light scattering (DLS)

Published:

30 Jun 2008

Withdrawn:

28 Feb 2017