FOURIER-TRANSFORM ION-CYCLOTRON RESONANCE MASS-SPECTROMETRY IN A 20 TRESISTIVE MAGNET

We present Fourier transform ion cyclotron resonance (FTICR) mass spec tra at a magnetic field of 20 T; more than twice the highest field pre viously used for FTICR, Our instrument is based on a resistive magnet installed at the National High Magnetic Field Laboratory, The magnet h as a 50 mm diameter bore and spatial inhomogeneity of similar to 1000 ppm over a 1 cm diameter spherical volume, However, FTICR mass resolvi ng power far in excess of magnet homogeneity is achieved routinely for ions produced by either electron ionization (EI) or matrix-assisted l aser desorption/ionization (MALDI), As examples, we show a MALDI mass spectrum of [M+H](+) quasimolecular ions of the peptide, human luteini zing hormone-releasing hormone (monoisotopic molecular weight, 1181.6 Da) at mass resolving power, m/Delta m>10 000; and an EI mass spectrum of molecular ions of the platinum cluster compound, Pt-4(PF3)(8) (ave rage molecular weight, 1484 Da at mass resolving power, m/Delta m appr oximate to 20 000, Much better FTICR MS performance is predicted for f uture NHMFL resistive magnets of higher spatial and temporal homogenei ty.