Current methodology instrumental variations

High-resolution MS has considerable merit in sequence analysis of peptides, since the technique allows the atomic composition of parent and fragment ions to be 

Chemical ionisation mass spectra (CIMS NHJ as ionisation reactant) can yield satisfactory spectra from underivatised peptides and field-desorption ionisation has been shown to give intense [M+ 1]+ ions from otherwise involatile peptide derivatives (for example, CH3—CO—Gly—Arg—Arg—Gly—OCH3 Buehler el al., 1974), but less sequence information is gained in these mild ionisation procedures because less fragmentation occurs and there are relatively few peaks in the mass spectrum. MALDF - matrix-assisted laser desorption ionisation MS - is an acronym that is encountered in recent literature for this ionisation technique. 

Biemann, K. (1989) in Protein Sequencing A Practical Approach, eds Findlay, J. B. C. and Geisow, M. I, IRL Press, Oxford, p. 99. 

and Lederer, E. (1971) in New Techniques in Amino Acid, Peptide, and Protein Research, Eds. Niederweiser, A. and Pataki, G., Ann Arbor Science Publishers, Michigan, p. 175. 

Desiderio, D. M. (1991) Mass Spectra of Peptides, CRC Press, Boca Raton, Florida. Edman, P. and Begg, G. (1967) Ear. J. Biochem., 1, 80. 

---