Structure selection, parent

All evidence of isotope patterns in the product ion spectrum of the m/z 304 parent (Fig. 19, bottom panel) disappears because the selected parent is monoisotopic—CiqHisNOF Cli. Justification for the absence of isotope patterns is identical to that of interpretation of the m/z 300 product ion spectrum. The detailed explanation of this excellent example serves to illustrate the care one needs to exercise in interpreting isotope patterns (or the lack thereof) in MS-MS spectra. At the same time, it demonstrates the structure-indicating power of careful interpretation. 

The structural objects which cannot be assigned the status of parent automatically become substituents on the selected parent unit. 

It is worth noting here that except for the atoms belonging to substituent chains (and only those chains not being considered as potential parent candidates) all other atoms of the input structure, on leaving the parent structure selection phase, are hierarchically distributed among nameable structural units. 

The above eight general principles of parent structure selection are the most important criteria in the determination of the seniority relations in the input structure by AutoNom. They do not represent all the rules implemented in the system, but they are the most relevant. 

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