Professor Robert C. Dunn named May 2023 Sutton Family Research Impact Award recipient

The Department of Chemistry congratulates Professor Robert C. Dunn on receiving the May 2023 Sutton Family Research Impact Award!

The Sutton Award is a monthly competition among chemistry faculty. Every month, the Chemistry Department Chair and Associate Chairs review the peer-reviewed papers published by chemistry faculty from the three previous months to select a winner. The recipient receives a $500 cash prize and is featured on the departmental website.

For a full list of winners, visit our Sutton Family Research Impact Award webpage.

Sample Plug Induced Peak Splitting in Capillary Electrophoresis Studied Using Dual Backscatter-Interferometry and Fluorescence Detection

By Miyuru De Silva and Robert C. Dunn^*

Published in Electrophoresis 2023, 44, 549-557

Capillary electrophoresis (CE) uses a small-bore, fused silica capillary to separate analytes under the influence of a strong electric field.  Species are separated based on their charge and size, and CE enables the rapid analysis of everything from inorganic ions to large proteins.  Given its high efficiency, flexibility, and low cost, CE has become ubiquitous in both research and industrial settings.  The appearance of unexpected peaks in CE, however, is common and creates significant problems.  Their appearance can lead to peak misassignments or lengthen the time of method development, as assay conditions and experimental parameters are varied to understand and mitigate the effects of the additional peaks.  Additional peaks can arise when a single analyte zone is split into multiple zones.  Understanding the underlying mechanism of this phenomena, recognizing conditions that favor its presence, and knowing how to confirm and eliminate the effect are important for efficient method optimization.  Recently, we combined back scatter interferometry (BSI) for refractive index detection with fluorescence detection to measure two orthogonal signal channels during a CE separation.  In this study, this approach was used to directly track and measure the location of the sample plug (refractive index) relative to the fluorescently active analyte zone.  Since the same laser excitation beam is used to generate both signals from the same detection volume, the resulting electropherograms are perfectly aligned for precise analysis.  We showed that analyte peak splitting can occur at the boundary between the sample plug and analyte peak.  We explore this effect by comparing a simplified diffusion-less model with systematic experimental studies to show that peak splitting can arise for both large and small molecules.  Comparison of simulations and experiments confirm the origin of the effect and the role that key parameters like length-to-detector, electroosmotic flow, and analyte mobility play.  These studies also reveal simple strategies to confirm the origin of the peak splitting and reduce its influence on separations.