A Strategy for the Determination of the Elemental Composition by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Based on Isotopic Peak Ratios

We propose a novel strategy for determining the elemental composition of organic compounds using the peak ratio of isotopic fine structure observed by high-magnetic field Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Using 3'-phosphoadenosine 5'-phosphosulfate and CTU guanamine as standard organic compounds, isotopic peaks derived from (15)N-, (34)S-, and (18)O-substituted forms were separated from (13)C-substituted species. Furthermore, these isotopic peaks were quantitatively detected and closely matched the natural abundance of each element. These data successfully led us to determine the one elemental composition in a standard independent manner. The approach should be particularly amenable to the metabolomics research field.