Fig. 10.

Elucidating mass spectra of complex materials requires advanced means of data analysis, such as van Krevelen diagrams, which are based upon assigned molecular formulae, and fragment- or molecule-specific Kendrick mass defect analyses [73]. Any dot in the van Krevelen diagram of a complex material represents a projection of the elemental ratios derived from assigned molecular formulae, irrespective of molecular mass. Accordingly, any of these dots could represent an intrinsic superposition of all feasible isomers from possibly different molecular compositions, sharing only their respective elemental ratios. The numbers of chemically reasonable isomers easily account for many millions of isomers seen for moderately sized molecules (a few hundred Daltons), even when only a few double bond equivalents and heteroatoms (e.g. oxygen) are present (see Fig. 11)