EFFECT OF LAMINAR-FLOW IN CAPILLARY ELECTROPHORESIS - MODEL AND EXPERIMENTAL RESULTS ON CONTROLLING ANALYSIS TIME AND RESOLUTION WITH INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY DETECTION

A capillary electrophoresis model was modified to include the effect o f laminar now. Experimental results using inorganic ions with a wide r ange of mobilities were compared to model predictions. The effect of l aminar now rate on analysis time, peak widths, peak asymmetry, and ele ctrophoretic resolution is discussed, The laminar now rate in the elec trophoresis capillary was controlled by regulating the sheath flow rat e in a concentric nebulizer interface. Laminar now in the direction of the detector allows the analysis of positive, neutral, and negative s pecies, all in one electrophoretic run, in less than 2 min, By increas ing the sheath electrolyte now rate, laminar how in the electrophoresi s capillary can be eliminated, resulting in increased resolution at th e expense of an increase in analysis time. At higher sheath flow rates , laminar now is generated in the electrophoresis capillary in the dir ection away from the detector to further retard the migration of charg ed species. When concentration overload contributes significantly to b and broadening, resolution may be enhanced by inducing a laminar how a way from the detector.