Effect of Laminar Flow in Capillary Electrophoresis: Model and Experimental Results on Controlling Analysis Time and Resolution with Inductively Coupled Plasma Mass Spectrometry Detection

Abstract

A capillary electrophoresis model was modified to include the effect of laminar flow. Experimental results using inorganic ions with a wide range of mobilities were compared to model predictions. The effect of laminar flow rate on analysis time, peak widths, peak asymmetry, and electrophoretic resolution is discussed. The laminar flow rate in the electrophoresis capillary was controlled by regulating the sheath flow rate in a concentric nebulizer interface. Laminar flow in the direction of the detector allows the analysis of positive, neutral, and negative species, all in one electrophoretic run, in less than 2 min. By increasing the sheath electrolyte flow rate, laminar flow in the electrophoresis capillary can be eliminated, resulting in increased resolution at the expense of an increase in analysis time. At higher sheath flow rates, laminar flow is generated in the electrophoresis capillary in the direction away from the detector to further retard the migration of charged species. When concentration ov...