Evaluation of an atmospheric pressure chemical ionization interface for capillary electrophoresis–mass spectrometry

Abstract

A simple and inexpensive approach to modify a commercial atmospheric pressure chemical ionization (APCI) interface was proposed for capillary electrophoresis–mass spectrometry (CE–MS). In order to accommodate lower flow rates in the range 1–10 μl/min, both sheath liquid and nebulizing gas were coaxially supplied to the nebulizer as an arrangement of pneumatically assisted electrospray interface. Since this paper focused on the primary study of the modified APCI interface, the performance of the interface was first evaluated by the direct infusion of a reserpine solution. Optimization of several APCI parameters, such as temperature of APCI vaporizer, nebulizing gas flow and APCI corona discharge current, were accomplished. The orifice dimension for the nebulizing gas flow was largely independent of the MS sensitivity when the nebulizing gas flow rate was ca. 0.4 l/min. A successful CE–APCI–MS separation is obtained using the modified APCI interface.