Appendix B Overview of Isotopes

M+

(M+1)+

(M+2)+

B

Figure B-3 Mass Spectrum of Angiotensin I at

Resolution 3,000

Isotope-limited resolution

In compounds with more than 100 carbon atoms, the height of the first 13C isotope peak exceeds the height of the 12C peak.

The mass range you analyze and the resolving power of the analyzer determine if you observe resolved isotope peaks in a mass spectrum.

Figure B-3represents angiotensin I at a resolution of 3,000. Isotopes are fully resolved, and sharp peaks are observed in the mass spectrum.

At lower resolutions, the shape of the individual peaks becomes less pronounced, or may not be differentiated at all. Figure B-4represents angiotensin I at a theoretical resolution of 1,000.

B-4 Applied Biosystems