Nanoparticles (NPs) have a broad range of applications in the chemical industry including paints, home & personal care products, and various plastic products. The physical and chemical properties (i.e. size, shape, and surface composition and charge) are critical to understanding their behavior in product development and application. Although numerous techniques have been explored for particle characterization, most of these focus on size and shape. Capillary electrophoresis (CE) separates particles based on electrophoretic mobility, which is related to both surface charge and particle size. Although CE is a highly efficient separation technique, particle peaks are typically broad and unresolved due to the convoluted distributions of size and charge. Therefore, we apply a two-dimensional off-line coupling of asymmetrical flow field-flow fractionation (AF4) and CE to separate and characterize NPs. The AF4 in the first dimension separates particles according to hydrodynamic diameter and hence reduces the impact of size distribution in CE separation, allowing sharper peaks in the second dimension CE electropherogram and improved resolution of the 2D contour plot as compared to either 1D separation. One major challenge in the application of this 2D technique is the large sample dilution after the AF4 fractionation leading to poor sensitivity for the CE. Multiple approaches have been explored in our research in order to bridge this gap, including ultracentrifugation and large volume sample stacking (LVSS). Also, we have developed Java code to extract and align CE data and perform baseline subtraction in order to obtain 2D contour plots. The improved separation and data processing platform is reproducible and robust, and holds great potential for characterization of a variety of industrial products with NPs components.

Development of two-dimensional offline coupling of asymmetrical flow field-flow fractionation (AF4) and capillary electrophoresis

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.