Observation of Field-Dependent Electrophoretic Mobility with Phase Analysis Light Scattering (PALS)

Abstract

The measurement of electrophoretic mobility is commonly done by laser Doppler electrophoresis (LDE). Recently, a more sensitive technique, phase analysis light scattering (PALS), has been developed with particular benefits for application to nonpolar systems. We have carried out PALS measurements of the electrophoretic mobility (μ) of modified silica particles as a function of applied electric field. Our results are in poor agreement with LDE measurements on the same system. We show that this difference might result from the way in which PALS measurements are performed and suggest that, in this case, the known field-dependent mobility will cause artifacts in the PALS data. When the mobility is field-dependent, this factor must be accounted for appropriately in PALS data analysis.

Surfactants with colloids: Adsorption or absorption?

“…Different surfactants have been used to disperse silica nanoparticles, depending on the nature of the solvent and the particle surface chemistry [15]. Several groups have recently studied charges of silica nanoparticles dispersed in alkanes in the presence of AOT [37][38][39][40][41], but only very small concentrations of silica can be dispersed due to the lack of Coulombic attraction between AOT anions and the negatively charged silica surfaces. Alumina nanoparticles can also be charged in alkanes in the presence of AOT [40].…”

Electrophoretic mobility of concentrated carbon black dispersions in a low-permittivity solvent by optical coherence tomography

“…In PALS, changes in the phase angle are used to determine the velocity of the particle in an electric field, making it 1000Â more sensitive than LDE. However, given the large electrode spacing (1-4 mm) [25], the small mobilities in nonpolar media require large potentials [26][27][28], which can produce undesired chemical reactions [24] and electrohydrodynamic instabilities [29]. Much smaller electric potentials may be used in differential-phase optical coherence tomography (DP-OCT) given the very narrow electrode spacing of 0.18 mm [25,30].…”

Behavior of yeast cells in aqueous suspension affected by pulsed electric field

“…The external electric field polarizes the dispersed particles, enhances their attraction and aggregation [7][8][9], increases migration of the particles and the surrounding ions [10] and may cause deformation of the fluid particles [11].…”