Synchronized Dual-Polarity Electrospray Ionization Mass Spectrometry

This work describes the synchronized dual-polarity (DP) electrospray ionization (EST) method and demonstrates the first DP EST mass spectra obtained using two mass spectrometers. Stable double Taylor cones were produced by applying two counter electric voltages with opposite polarities to one electrosprayer. The development of double Taylor cones required higher extraction voltages than conventional EST, but DP EST worked effectively at liquid flow rate range three times wider than conventional EST. Using pure methanol, the emission currents of the two cones were neutralized and no current was drawn from the sprayer. Synchronized DP mass spectra were obtained using electrospray calibrants dissolved in methanol solution of low water content. For bovine insulin with conventional electrospray solution, the gas-assisted electrospray delivered satisfactory sensitivity and stability for routine mass analyses. (J Am Soc Mass Spectrom 2009, 20, 2254-2257) (C) 2009 American Society for Mass Spectrometry