Capillary Electrophoretic Characterization of Platinum and Silver Nanoparticles in Aqueous Solution Prepared by a Solution Plasma Process

Aqueous solutions of platinum nanoparticles (PtNP) and silver nanoparticles (AgNP) were prepared by a solution plasma process in the presence of hydrogen peroxide. Both nanoparticle solutions did not show visible-range photo-absorption by surface plasmon resonance, and capillary zone electrophoresis (CZE) was utilized for the characterization of the nanoparticles. An anionic broad peak was detected with the PtNP by the CZE analysis, whereas both an anionic and an electrically neutral peaks were detected with the AgNP. Serious shot signals attributed to the agglomerate of the nanoparticles were not detected with either the PtNP or the AgNP, and the nanoparticles were stably dispersed in an aqueous solution for at least a few tens of week. Dispersion stability of the nanoparticles was also evaluated in salt solutions, as well as with ethanol co-solvent.