Abstract
Capillary electrophoresis (CE) is a powerful technique that is simple to perform, provides rapid results, has high efficiency and resolution, and involves low sample consumption. However, the benefits provided by the high number of theoretical plates obtained with CE can be overshadowed by the low sensitivity of UV-Vis detection system. We describe a rapid, simple, and highly efficient CE based method for the analysis of nanoparticles (NPs). In this study, we used the reversed electrode polarity stacking mode (REPSM) of CE to assess the feasibility of enhancing the detection of Au NPs and Au/Ag NPs. We tried to find the optimum parameters such as the length of time for which the REPSM was applied, the concentrations of the buffer and the sodium dodecylsulfate (SDS) surfactant, and the pH. Under the optimized on-line enhancement conditions [buffer: 3-cyclohexylamino-1-propanesulfonic acid (CAPS; 10 mM) and SDS (40 mM) at pH 10.0; applied voltage: 20 kV; REPSM applied for 24 s], the detection limits of the Au NPs and Au/Ag NPs increased by ca. 30- and 140-fold, respectively. These two NP samples could be resolved within 4 minutes. In addition, when the NPs were subjected to on-line enhancement and separation by CE using diode array detection (DAD), this approach allowed chemical characterization of the NP species. Our results suggest that such CE analyses will be useful for accelerating the rates of fabrication and characterization of future nanomaterials.