This invention relates to an electrospray emitter which comprises an emitter body comprising an inlet orifice, an outlet orifice and a channel connecting the inlet orifice and the outlet orifice; and a coating formed at least on the outer surface of the exit end of the emitter body with a material of low surface energy. The emitters can produce stable electrospray without the aid of any nebulizing gas in the flow rate range of micro-to nano-liters, depending on the surface tension of solvent including distilled water with a high surface tension. The electrically non-conductive nature of their tips virtually eliminates electrical discharge and allows stable electrospray in the negative ion mode. To prevent loss of analytes during delivery between the emitter and analytical devices, e.g., liquid chromatography, a method of coating the inner surface of the connecting line with chemically inert material of low surface energy is also described.