That's why we are strongly opposed to anything related to buying DMT and/or getting from unknown sources. Who knows what you have there? Maybe flour, maybe some RC, maybe some toxic substance, maybe DMT, maybe a mix of these things ?
If you know the person who extracted it and its someone close, why dont you ask exactly how they extracted, using what chemicals, etc? Write it down and ask us here. If you dont know the person, I suggest you forget about this, start reading our forum, the FAQ, the different extraction teks, and do it yourself. You dont have to be a chemist, it's not harder than, say, cooking a meal. Just read and you'll get it. Feel free to ask any questions you cant find the answer to in the FAQ or elsewhere here.
Lastly, DMT can be powder, but certainly not with the consistency of flour. What vitalstatistix said, specially the first option, would clean up DMT if it was impure, but the thing is we dont even know if you have DMT in the first place, maybe it's something else, soem other active alkaloid that might come across in this clean up step... So ask the person, or extract it yourself.
If you insist on trying this out no matter what, please at least buy some reagent like ehrlich, marquis, or similar, and check the color reactions in the sticky thread in the testing subforum linked in my signature, to help identifying it.
Be safe!