Schematic illustrating conceptual and experimental approaches to representing and searching through chemical space. As shown in (A), the monoisotopic mass of folate (M0) is projected into the range of possible chemical species in chemical space. Many distinct points in chemical space are nearly indistinguishable in this projection (“degeneracy”). In (B), the points are projected into 3 dimensional space where the number of nitrogen and carbon atoms in each chemical formula is known, and in (C), the isotopic intensities of M1 and M2 peaks relative to the M0 peak form other axes along which formulae can be projected.
Bowen et al. BMC Genomics 2011 12(Suppl 1):S6 doi:10.1186/1471-2164-12-S1-S6