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In this study, a new method is described for integrating an electrospray ionization interface to a mass spectrometer with a capillary electrophoresis channel. We have fabricated the ESI-MS device composed of the metal emitter tip, allowing the generation of an efficient nanospray for protein detection, and CE separation channel monolithically in a glass microchip. A triangular-shaped gold emitter tip was formed by electroplating at the end of the separation channel. As an ESI source, this emitter structure aided the formation of a stable Taylor cone. It is easily fabricated by MEMS technology and more robust than that of silica or polymer recently reported. Moreover, this approach is less involved than applying a conductive coating to the exit end to establish electrical contact. As such, the interface is less dependent upon the longevity or durability of such coating, factors that have been consideration in the sheathless interfaces. The spraying stability was evaluated and the ESI-MS experiment was performed by spraying standard peptides for mass spectrometric analysis. The spraying was stable, with a relative standard deviation of 2.9%. The CE/ESI-MS analysis was performed by separating and spraying standard peptide mixture of Bradykinin 1-5, Bradykinin 1-8, and Angiotensin I. Each peptide was separated successfully and singly-charged peaks and doubly-charged peaks of each peptide were detected, respectively. Direct comparisons with conventional ESI-MS system using glass or fused silica emitters showed very similar performance with respect to signal intensity and stability.
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