Generation of electrospray from a solution predeposited on optical fibers coiled with a platinum wire

This study examines the feasibility of generating electrospray directly from the tip of two optical fibers bound together with Teflon tape. This approach does not require a capillary and syringe pump. The electrospray source is simply constructed by coiling the two optical fibers with a platinum (Pt) wire. The optical fibers extend beyond the Pt coil for approximately 1 cm. The sample solution is predeposited on the Pt coil by a micropipette. As the high voltage required for electrospray is applied to the coil, the sample solution moves along the grooves between the two optical fibers. A stable electrospray is subsequently generated at the tip of the fibers. The mass spectra of insulin, lysozyme, and ubiquitin are exactly the same as those obtained by conventional electrospray using a capillary and syringe pump. Rapid determination of the active ingredient in a tablet by this technique is demonstrated.