ELECTROSPRAY-IONIZATION ION MOBILITY SPECTROMETRY

An improved electrospray ionization source for ion mobility spectromet ry was developed by making three salient modifications to the electros pray needle, First, the needle was removed from the ion drift region, reducing neutralization of charged drops and ions on the walls of the ion mobility drift tube. Second, the tip of the spray needle was elect rically insulated, extending the voltage range with which a stable ele ctrospray could be achieved. Third, the needle was cooled, eliminating problems associated with solvent volatilization in the spray needle. Ion mobility spectra of cytochrome c and Triton X-100 were compared wi th those obtained by electrospray ionization mass spectrometry. While direct mass/charge comparison with ion mobility was not possible, simi lar electrospray ion patterns between the IMS and MS data suggest that the electrospray ionization source for IMS behaved in a manner consis tent with that of other electrospray ionization sources. In addition, mass assignments of IMS ion peaks, made by matching patterns from mass spectra, fit well with those expected from IMS theory.