Appendix B Overview of Isotopes
B.1 IsotopesB
Overview Many elements in their natural state exist as one of several isotopes. An isotope is one of two or more atoms with the same atomic number but a different mass. The most abundant isotope of carbon is 12C, but natural carbon also contains 13C and 14C.
Because a mass spectrometer measures
The mass spectrum of methane (Figure
16Da (12CH4) and a peak representing the isotope at 17 Da (13CH4). The relative abundance of the ions is about 99:1.
12C
13C
Figure
1. Meth. Enzymol., McCloskey, J.A, ed., 1990, 193, 869.