578
Anal. Chem. 1984. 56.578-581
Registry No. Carbon, 7440-44-0;ferrocyanide, 13408-63-4.
LITERATURE CITED Van der Llnden, W. E.; Dieker, J. W. Anal. Chlm. Acta 1980, 119. 1-24. Laser, D.; Ariel, M. J . Elecfroanal. Chem. 1974, 52, 291-303. Randln, J. P.; Yeager E. J. Elecfroanal. Chem. 1975, 5 8 , 313-322. Taylor, R. J.; Humfray, A. A. J. Elecfroanal. Chem. 1973, 42, 347-354. Evans, J. F.; Kuwana, T. Anal. Chem. 1979, 5 1 , 358-365. Engstrom, R. C. Anal. Chem. 1982. 5 4 , 2310-2314. Gunasingham, H.; Fleet, B. Analyst (London) 1982, 107, 896-902. Gunasingham, H.; Fleet, B. Analyst (London) 1982, 108, 316-321. Dieker, J. W.; Van der Linden, W. E.; Poppe, H. Talanfa 1978, 2 5 , 151-155. Jordan, J. Pennsylvania State Unhwsity, University Park, PA, personal communication, 1979, Robbat, A. Ph.D. Thesis, Pennsylvanla State University, University Park, PA, 1980. Amatore, C.; Saveant, J. M.; Tessier, D. J. Elecfroanal. Chem. 1983, 146, 37-45. Zak, J.; Kuwana, T. J. Am. Chem. SOC. 1982, 104, 5514-5515. Rusilng, J. F. Anal. Chem. 1983, 5 5 , 1719-1723. Kulkarni, C. L.; Scheer, B. J.; Rusiing, J. F. J. Elecfroanal. Chem. 1982, 140, 57-74. Rusiing, J. F. Anal. Chem. 1983, 5 5 , 1713-1718. MeRes, L. CRCCrif. Rev. Anal. Chem. 1979, 8 , 1-53. Kuwana, T.; Bublitz, D. E.; Hoh, G. J. Am. Chem. Soc. 1980. 82, 5811-5817.
Bard, A. J.; Faulkner. L. R. "Electrochemical Methods"; Wlley: New York, 1960. Jordan, J. AnalChem. 1955, 2 7 , 1708-1711. Blaedel, W. J.; Engstrom, R. C. Anal. Chem. 1978, 5 0 , 476-479. Kawlak, J.; Jerdral, T.; Galus, 2. J . Elecfroanal. Chem. 1983, 145, 163-1 7 1. Siegbahn, K.; Nording, C.; Fahlman, A; Nordberg, R., Hamrin, K.; Hedman, J.; Johansson, 0.; Bergmark, T.; Karlsson, S.; Llndgren, I.; Lindberg, B. "ESCA: Atomic Molecular, and Solid State Structure Studied by Means of Electron Spectroscopy"; Almqulst and Wlksells: Uppsab, 1967. Proctor, A.; Sherwood, P. M. A. Carbon 1983, 21, 53-59. Stutts, K. J.; Korach, P. M.; Kuhr, W. G.; Wightman, R. M. Anal. Chem. 1983, 5 5 , 1632-1634.
Department of Chemistry, U-60 University of Connecticut Storrs, Connecticut 06268
James F. Ruslina-
RECEIVED for review June 20,1983. Accepted November 23, 1983. This work was partially supported by the National Cancer Institute and the National Institute of Environmental Health Sciences through Public Health Service Grants No. lR01CA33195 and No. lROlES03154, respectively.
Cesium Ion Desorption Ionization with Fourier Transform Mass Spectrometry Sir: We report the combined use of particle-induced desorption ionization (DI) (Cs+ ion 2-3 keV) and Fourier transform mass spectrometry to produce mass spectra of nonvolatile/thermally labile biomolecules. Several authors have discussed the rather unique capabilities of FTMS for analyzing large biomolecules (1-6); however, the intrinsic limitations of FTMS place some restrictions on the ionization methods employed (5). Specifically, the large volumes of residual gases required for operating discharge ionization sources, e.g., Ar, Xe, etc., preclude the use of these sources, and the residual background from liquid matrices used with fast-atom bombardment (FAB) represent a similar limitation. The instrument background from discharge ionization sources and liquid matrices are incompatible with FTMS due to pressure limitations on mass resolution and limitations on dynamic range (7). In order to utilize the novel features of FTMS for analysis of biomolecules it is essential that the high vacuum conditions (
