Evaluation of an Ultrasonic Nebulizer Interface for Capillary Electrophoresis and Inductively Coupled Plasma Mass Spectrometry

Abstract

An interface for capillary electrophoresis (CE) and inductively coupled plasma mass spectrometry (ICP-MS) is developed with a commercial ultrasonic nebulizer. The CE ground path was provided through a coaxial liquid electrolyte flow surrounding the CE capillary. To accommodate this dual capillary arrangement, the ultrasonic nebulizer spray chamber sample uptake tube inner diameter was enlarged. Metallothioneins were separated and detected to characterize the interface and to compare it with a concentric-glass nebulizer interface. Capillary electrophoresis resolution was unaffected by the ultrasonic nebulizer interface. Signal intensity was improved 3.6- to 8.4-fold compared to the concentric nebulizer arrangement, while signal-to-noise ratio improvement was only 1.3- to 2.8-fold. Concentration detection limits for114Cd,111Cd,64Zn, and66Zn are 0.082, 0.039, 1.18, and 1.15 ppm in metallothionein, while the corresponding absolute detection limits are 2.5, 1.2, 37, and 36 fg, respectively.