I wouldn't call it synth discussion if it doesn't go into how to make it. AFAIK discussion of purification procedures not including actual synthesis are permitted, as is discussion of byproducts created by certain synthetic routes without going into 'how do I make xxx?' or 'where do I get xxx chemical and how do I use it' type stuff, blatant instructions or questions surrounding how to make drugs, or where to buy them.
I don't know the route of synthesis used here. But just a wondering, is if it was produced as distrbuted in this case, via the nitroalkene and reduction to the drug. The nitroalkenes formed as intermediates in the Henry/Knoevanagel condensation route are quite physically irritant, at least some are, no idea if its universal, but given the nitro functional group is generally an oxidizing agent, its very likely to irritate mucous membranes. Which is why i wonder if it was used to produce this batch of camphetamine...perhaps some of the nitro intermediate may have been unreduced, and made its way into the product if this route was used for synthesis.
As an example, exposure to the nitropropene that is the immediate intermediate precursor to 2C-D on the fingertips was slightly irritating although given the thickened skin on the hands, not actually painful, just irritant and unpleasant. Getting a trace in the eye....or touching the mucous membranes of the mouth, the tongue, or scratching one's nose and exposing the nasal epithelia to (2,5-dimethoxy-4-methyl)-1-phenyl-2-nitroethene resulted in quite substantial irritation.
I cannot imagine how much snorting a line of that, if say, a chemist intended to make 2C-D, and thought the nitrostyrene may be active as well, and tried insufflating some (not this was not done by the person who observed the irritant properties, it would be a stupid mistake, and an obvious one at that, and should most certainly not be made by a chemist with half a brain
but snorting a line, would hurt like blazes, the nitro-norbornene condensation product with benzaldehyde would almost certainly be equally irritant.
Nitro group-containing substances generally aren't good for the body, especially aromatic nitros, although these intermediates in question are not substituted with a nitro group on the aromatic ring, but on the alkyl/alkenyl sidechain instead, but still likely not exactly health food. However I don't believe there is going to be any real damage done by testing a bit of this stuff.
If it IS present, its quite likely to be colored brightly in the pure state, or when there is a concentrated bit to be viewed. The nitro group on a phenyl-aminoalkane or aminoalkene often gives a yellow color (as apparently, does the aromatic nitro to 2C-N, and probably by extension DON. The nitroalkene intermediate is very likely, if it follows the pattern for the other phenethylamines, going to be insoluable in water, and highly soluable in methanol (toxic), with most likely, low but existant soluability in isopropanol.
Recrystallization from ice-cold water, and filtering the solution through fine filter paper, preferably a layer or two, washing the filter after the main bulk of compound has been filtered to obtain the traces of camphetamine that get soaked into the paper would exclude the nitronorbornene if the Henry rxn was used.
If so, the drug will be in the water fraction, rather than any crap remaining in the filter. Evaporation of the water, or addition of a nonpolar solvent, such as toluene, xylene to a solution of camphetamine (as a salt) basified with NaOH to yield the freebase, which should have an oily, water insoluable character, as does meth, MDxx or amphetamine base, will take it up into the nonpolar fraction, which could be washed with water, to remove water soluable but nonpolar-insoluable byproducts if any such byproducts exist, the tolene, naptha, xylene etc, can either be evaporated, or have dry hydrochloric acid gas passed through to reform a crystalline salt (this could then be dissolved in a minimum of boiling alcohol, then allowed to crystallise via first freezing (lowers soluability of the soluable product, allowing some, but not all, to precipitate out, this will likely be quite pure, if the above has been performed, and then evaporating to yield the rest.
None of this is synthesis, you won't create anything new, just remove byproducts.
Additional data-the hydrochloride salts of many amphetamines, including 2,5-dimethoxy, and ring-unsubstituted amphetamines, are soluable in the nonpolar chlorinated solvents DCM and chloroform.