Techniques for Electro- and Magnetokinetic Particle Characterization

The applicability of magnetic particles is strongly dependent on the electric surface charge and the magnetic susceptibility of the individual particles. Particle electrophoresis is a common method to control the production process and to assess the final colloidal solution. Particles within a wide size range are used and different measuring principles must therefore be applied. Laser based techniques using the Doppler or image transduction effect are very useful for the estimation of the mean electrophoretic mobility of particles within the size range below 500 nm. Automated techniques with image analysis are preferred for the analysis of mixtures of particles with sizes larger than 500 nm and with a broad variation of the surface charge. Electrophoretic fingerprints representing the mean electrophoretic mobility of a given particle suspension versus pH and ionic strength of the media are a helpful method for the assessment of the production and modification procedure of particles.