Much more precise and reliable than PALS based zeta measurement
Phase analysis light scattering (PALS), an ensemble technique based on laser doppler velocimetry, is the best known technology for the determination of zeta potential of nanoparticle suspensions. Although readily available, ensemble techniques (e.g. PALS), as opposed to single particle measurement techniques, such as TRPS, can only measure and calculate the average particle mobility and hence detailed single particle information is lost, in particular when measuring polydisperse samples. TRPS is the only available technology that provides simultaneous in-suspension information about particle size and zeta potential on a particle-by-particle basis, guaranteeing accurate analysis of multi-modal and polydisperse samples (see figure). Whilst a mixed sample of bare and carboxylated polystyrene spheres with equivalent sizes (~400 nm) but different zeta potentials was perfectly resolved with TRPS, the two particle populations could not be distinguished with PALS.