Initial implementation of an electrodynamic ion funnel with Fourier transform ion cyclotron resonance mass spectrometry

Fourier transform ion cyclotron resonance (FTICR) mass spectrometry has bec ome a widely used method to study biopolymers. The method, in combination w ith an electrospray ionization (ESI) source has demonstrated the highest re solution and accuracy yet achieved for characterization of biomolecules and their noncovalent complexes. The most common design for the ESI interface includes a heated capillary inlet followed by a skimmer having a small orif ice to limit gas conductance between a higher pressure (1 to 5 torr) source region and the lower pressure ion guide. The ion losses in the capillary-s kimmer interface are large (estimated to be more than 90%) and thus reduce achievable sensitivity. Ln this work, we report on the initial implementati on of a newly developed electrodynamic ion funnel in a 3.5 tesla ESI-FTICR mass spectrometer. The initial results show dramatically improved ion trans mission as compared to the conventional capillary-skimmer arrangement. An e stimated detection limit of 30 zeptomoles (similar to 18,000 molecules) has been achieved for the analysis of the proteins with molecular weights rang ing from 8 to 20 kDa. (J Am Soc Mass Spectrom 2000, 11, 19-23) (C) 2000 Ame rican Society for Mass Spectrometry.