If the MS registers ions with a mass greater than that of PEA that you could attribute to a certain ionized fragment of the PEA-NBOMe structure I guess it works pretty well in this case, the same could be said for counting C's and/or H's using NMR integral areas. Also, a spectrum of an existing NBOMe compound could serve as a good example of what kind of ionized fragments would be created, unless I am mistaken.
With NMR, you can generate a software approximation to compare.
In general I would be inclined to use the measurement method there are existing spectra for, it would depend on the NMR resolution available (some old machines could be a pain in the ass for complex results), and the more complex a compound is the less inclined I would be to use NMR because of elucidation. Ibogaine or salvinorin would seem like a lot of work for example.
Then again, I flunked a lot of this stuff so that could explain one thing or another.
With NMR, you can generate a software approximation to compare.
In general I would be inclined to use the measurement method there are existing spectra for, it would depend on the NMR resolution available (some old machines could be a pain in the ass for complex results), and the more complex a compound is the less inclined I would be to use NMR because of elucidation. Ibogaine or salvinorin would seem like a lot of work for example.
Then again, I flunked a lot of this stuff so that could explain one thing or another.
(I wish I had now)