Plasma Desorption Mas Spectrometry: Coming i f Age Robert J. Cotter Middle Atlantic Mass Spectrometry Facility Department of Pharmacology and Molecular Sciences The Johns Hopkins University Baltimore, MD 21205
Plasma desorption mass spectrometry (PDMS) uses the high-energy fragments emitted from the spontaneous fission of || 2 Cf to desorb and ionize large and nonvolatile molecules for mass analysis. The method is also known as fission fragment induced desorption (FFID). Much of the development of PDMS has occurred in nuclear laboratories, where accelerators have been used to generate heavy particles with energies (about 1 MeV/nucleon) similar to those of fission fragments. Thus the term heavy ion induced desorption (HIID) is often used to distinguish PDMS from the lighter and less energetic primary particle methods used in secondary ion mass spectrometry (SIMS) and fast atom bombardment mass spectrometry (FAB-MS). Since plasma desorption was introduced by Macfarlane and Torgerson in 1974 (i), the size of molecules successfully mass analyzed by the technique has steadily increased and now includes a large number of peptide hormones, growth factors, and other small proteins (2) in the mass range of 5,00025,000 amu. Particularly impressive is the recent recording of the PDMS spectrum of porcine pepsin (Figure 1) with a molecular weight close to 35 kDa 0003-2700/88/0360-781 A/$01.50/0 © 1988 American Chemical Society
INSTRUMENTATION
Figure 1. Plasma desorption mass spectrum of porcine pepsin obtained on a BIOION 20 (Uppsala, Sweden). The sample is a mixture of residues 1-42 and 1-44 (34,504 and 34,688 amu, respectively, calculated from the sequence), which are unresolved in the spectrum. (Adapted with permission from Reference 3.)
ANALYTICAL CHEMISTRY, VOL. 60, NO. 13, JULY 1, 1988 · 781 A
