Preparation of Durable Emitter of Electrospray Mass Spectrometry by Covalently Coating the Fused-Silica Capillary Tip with Carbon-Nanotube Sol-Gel Composite Material

A simple approach for the preparation of emitter of electrospray ionization mass spectrometry by covalently coating the fused-silica capillary tip with the conductive carbon-nanotube sol-gel composite material(CNTSCM)is described.The CNTSCM was prepared by dispersing single-walled carbon nanotubes in the sol composed of a mixture of 3-glycidoxypropyltrimethoxysilane and 3-aminopropyltrimethoxysilane,and ethanol.The long-term sta-bility of the prepared ESI emitters was demonstrated by at least 180 h of continuous use.Signal intensity obtained by the prepared emitter was mass-flux sensitive when the flow rate was lower than 500 nL/min,while the signal in-tensity performed a concentration dependence when the flow rate was in the range of 500-800 nL/min.The use-fulness of such a prepared emitter was demonstrated by the analysis of various types of samples such as organic small molecular drugs,oligosaccharide,peptide,and protein.