Abstract
The feasibility of separation of nanoscale metal particles either by size or shape with capillary electrophoresis (CE) is demonstrated. This dissertation is composed of two main parts (i) size separation of gold nanoparticles and (ii) shape separation of silver nanoparticles. In the first part, a separation method by adding anionic surfactant and polymer was established. The separation mechanism of surfactant and polymer was probed. In the second part, a dynamic pH gradient sweeping on-line concentration was build up and separation of different shaped silver nanoparticles can be achieved. The separation can be confirmed with fraction collection to take TEM images. CE with anionic surfactant, sodium dodecyl sulfate (SDS), and linear polymer, poly (ethylene oxide) (PEO), can successfully separate gold nanoparticles with different sizes. This work demonstrates the feasibility of employing CE to separate gold particles in nanoscale regimes. After addition of SDS and PEO to the buffer, particles with different sizes were separated simultaneously. Parameters including buffer concentration, SDS concentration, percentage of PEO, pH value, and applied voltage are investigated to obtain the optimized separation resolution. The separation mechanism of PEO and the effect of SDS are also discussed here. Most important of all, a linear relationship between the migration time and particle size is obtained in the particle diameters range of 5 – 40 nm. The coefficient of variation of migration time for 5 nm and 20nm gold nanoparticles are 3.5 and 4.1 %, respectively. Real samples made by microwave heating method have been analyzed and the analytical results of CE show a good fit with the statistical size distribution from SEM images. This study provides an alternative method for rapid separation and characterization of nanoscale gold with different particle sizes. This study also demonstrated the feasibility of CE use to separate silver nanoparticles with different shapes. Herein, a dynamic pH gradient-sweeping on-line concentration method had been established and employed to separate silver nanoparticles. The concentration of SDS and pH difference between leading and terminal buffer were optimized. More than 12 runs showed a very similar（CV＜1.8 % in migration time）on-line concentration effect. Besides, the mechanism of the dynamic pH gradient-sweeping is proposed in this study. To confirm the effect of this separation method, a fraction collection is used to collect the separated silver nanoparticles and observe by TEM. From TEM images, spherical nanoparticles are successfully separated by CE and the particles of 2nd peak in electropherogram were collected.