Comparison of potential of capillary zone electrophoresis and Malvern's improved laser Doppler velocimetry for characterisation of silica nanomaterials in aqueous media

Two silica certified reference nanomaterials containing 50- and 100-nm particles were used for comparing electrophoretic mobility measurements by capillary zone electrophoresis and Malvern's improved laser Doppler velocimetry under the same experimental conditions. Phosphate buffer solutions with concentrations of 2.5 and 5.0 mM, at pH 8.5 and 6.2 were used for preparation of dispersions. These dispersions were stable sufficiently to perform measurements. The values of absolute electrophoretic mobility determined by a Malvern's improved laser Doppler velocimetry were found to be lower than those determined by a capillary zone electrophoresis. In addition, the results of size measurements by dynamic light scattering and scanning electronic microscopy were compared. The reasons for differences in measured values are discussed.