Lophophora cacti which contain mescaline also contain: tyramine, N-methyltyramine, hordenine, candicine, anhalamine, lophophorine, pellotine, O-methyl-pellotine, N,N-dimethyl-3-methoxytyramine, dopamine, epinine, 3-methoxytyramine, N-methyl-mescaline, N-formylmescaline, N-acetylmescaline, N-formylanhalamine, N-acetylanahalamine, isoanhalamine, anhalinine, anhalidine, anhalotine, isoanhaladine and anhalonidine.
While not all of these compounds are active, they can affect the experience produced.
Pure mescaline is simply 3,4,5-trimethoxy-phenethylamine.
Total alkaloid extracts contain these other alkaloids, while a mescaline extract will contain only 3,4,5-trimethoxy-phenethylamine.
When dealing with the salts of mescaline one must take weight into consideration as well, when the acids protonate the freebase it adds weight, depending on the acid the weights will vary, so when it comes to dosing mescaline salts one must remember this.
If you could be a little more specific it would be much easier to respond.
These links should help:https://erowid.org/chemicals/mescaline/http://troutsnotes.com/trouts-notes-library/