FOURIER-TRANSFORM ELECTROSPRAY INSTRUMENTATION FOR TANDEM HIGH-RESOLUTION MASS-SPECTROMETRY OF LARGE MOLECULES

Mass spectrometry instrumentation providing unit resolution and 10-ppm mass accuracy for molecules larger than 10 kDa was first reported in 1991. This instrumentation has now been improved with a 6.2-T magnet r eplacing that of 2.8 T, a more efficient vacuum system, ion injection with controlled ion kinetic energies, accumulated ion trapping with an open-cylindrical ion cell, acquisition of 2M data points, and updated electrospray apparatus. The resulting capabilities include resolving power of 5 x 10(5) for a 29-kDa protein, less than 1-ppm mass measurin g error, and dissociation of protein molecular ions to produce dozens of fragment ions whose exact masses can be identified from their mass- to-charge ratio values and isotopic peak spacing.