A new interface for combining capillary electrophoresis with inductively coupled plasma-mass spectrometry

This paper describes the development and design of a new, efficient, simple and robust interface for coupling capillary electrophoresis (CE) with inductively coupled plasma-mass spectrometry. The interface is based on a modified microconcentric nebulizer which permits a low flow rate of about 6 μL/min in the free aspiration mode. This interface construction provides an electrical connection for stable electrophoretic separations and adapts the flow rate of the electro-osmotic flow inside the CE capillary to the flow rate of the nebulizer for efficient transport of the analytes into the plasma. By optimization of the fluid mechanical properties the interface prevents the nebulizer from causing any laminar flow in the CE capillary and thus the high resolution power of CE can be preserved. Furthermore, this new device permits independent optimization of the nebulization from the CE whereby exact positioning of the CE capillary is not necessary, thus enabling fast exchange. A low dead volume spraychamber has been constructed which circumvents any band broadening of the sharp CE signals. Peak widths down to 3.5 s comparable to CE with UV detection are possible. Received: 5 February 1999 / Revised: 21 April 1999 / Accepted: 23 April 1999