Influence of buffer composition on the capillary electrophoretic separation of carbon nanoparticles

Carbon nanoparticles obtained from the flame of an oil lamp were examined by means of capillary electrophoresis. The influence of buffer composition on the separation of the mixture of negatively charged carbon nanoparticles was studied by varying buffer selection, pH, and concentration. The electrophoretic pattern was affected by both the co- and counter-ion in the buffer solution, influencing selectivity and peak shape. The capillary electrophoretic separations at different pH revealed species with large electrophoretic mobilities under a wide range of pH. The mobility of selected species in the mixture of nanoparticles showed a strong dependence upon the solution ionic strength. The mobility of these nanoparticles as a function of ionic strength was compared to classical electrokinetic theory, suggesting that under the experimental conditions utilized, the species are small, highly charged particles with appreciable zeta potentials, even at low pH.