DEVELOPMENT OF A NANO-ELECTROSPRAY MASS-SPECTROMETRY SOURCE FOR NANOSCALE LIQUID-CHROMATOGRAPHY AND SHEATHLESS CAPILLARY-ELECTROPHORESIS

A Fisons Quattro I electrospray ionization (ESI) source has been modif ied to produce stable electrospray ion currents at flow rates as low a s 50 nL/min, The original counter electrode and skimmer cone lens of t he Fisons ESI source have been replaced with a spherical cone lens. Th is improved source provides a greater range of x,y,z positioning of a stainless steel tip resulting in a stable ion signal for flow rates of 50 nL/min to 2 mu L/min, A tapered stainless steel electrospray tip ( 50 mu m i,d,) was evaluated for mass spectrometry using nano-liquid ch romatography (50 pm i,d,, flow rate = 120 nL/min) and sheathless capil lary electrophoresis, The analysis of a nonionic surfactant, octylphen ol ethoxylate, was accomplished with both nanoscale separation techniq ues. (C) 1998 John Wiley & Sons, Ltd.