  We characterize the electro-phoretic motion of charged sphere suspensions in
the presence of substantial electro-osmotic flow using a recently introduced
small angle super-heterodyne dynamic light scattering instrument (ISASH-LDV).
Operation in integral mode gives access to the particle velocity distribution
over the complete cell cross-section. Obtained Doppler spectra are evaluated
for electro-phoretic mobility, wall electro-osmotic mobility and particle
diffusion coefficient. Simultaneous measurements of differing electro-osmotic
mobilities leading to asymmetric solvent flow are demonstrated in a custom made
electro-kinetic cell fitting standard microscopy slides as exchangeable
sidewalls. Scope and range of our approach are discussed demonstrating the
possibility of an internal calibration standard and using the simultaneously
measured electro-kinetic mobilities in the interpretation of microfluidic
pumping experiment involving an inhomogeneous electric field and a complex
solvent flow pattern.
