I'd say one test you didn't mention is inhaling some of it's vapour. However if it is suspect to you that is a risk.
Get hold of some light naphtha and warm it in a water bath to to roughly 40°c. Add your substance at a ratio of around 1000mg 'DMT' to 50ml of naptha. This is probably too much nps at that temperature but it wont really hurt.
Chemical Guide to classic Psychedelics (DMT, 5-MeO-", Mescaline, Harmalas, Salvinorin A, ...) - Advanced/Enhanced chemistry - Welcome to the DMT-Nexus this thread will give you a more comprehensive understanding of DMT solubility in all well known np solvents.
Stir gently. Anything that does not disolve after a few minutes can be saved for later experimentation.
Syphon off the NPS/dmt solution allow to cool to room temp. Seal container and place in freezer below -6°c for minimum 24 hours. After time elapsed remove and follow the recovery process of a freeze precip that can be found well documented on the forum many times over.
If nothing crashes out in the freezer the saturation may be too low. Attempt a partial evap and freeze again.
Your product may well still not be DMT. But at the least your secondary waste solid that you saved for later is most likely not dmt.
If I'm missing any of the marks hopefully someone will correct me here. But this should get you started.