10.1 Required Information to Confirm and Identity

1. The molecular mass should generally be verified experimentally. In the absence of running CI experiments, the absence of an MI signal in the mass spectrum for a compound for which the MI is reasonably expected to be absent may taken as confirmatory. However, if an EI molecular ion is not observed, a chemical derivative can be synthesized and the molecular mass of the derivative measured by EI mass spectrometry. This technique uses a combination of chemical and physical properties to determine molecular mass.
2. Reasonable reactions should be proposed for the formation ions corresponding to the major signals in the mass spectrum. There is no set minimum number of ions to 'work,' though six or more are often addressed. Major ions are those that most strongly correlate with structure, not necessarily the largest in the spectrum. Ion that differentiate a structure from isomers, analogues and homologues are very important, as are those that discriminate between functional classes.
3. Isotope peaks should be present on the molecular ion signal and all significant product ion signals. Some small ions not considered significant that have missing isotope peaks may not be of great concern, but it must be remembered that sometimes very important signals (to correlate to structure) are of low intensity.
4. The isotopic distributions for both molecular ion and significant product ion signals must be consistent with the proposed structure correlating with those signals.