Thizz_Machine_138 and Swerlz pretty much hit the nail on the head here OP and I'm going to close this before you get flamed too harshly.
We are definitely not going to have any better idea of what you have purchased than you will, and MD Powder could be slang or a brand name for literally anything. Generally people like to have a solid assumption of what they are purchasing when they buy it and preferably have that backed up with the actual name of the chemical.
Whether the substance you obtain is the one you believe you have purchased is a whole other ballgame requiring reagent testing as the above poster noted, but you have to know which chemical you think you have first.
So yeah please talk to your supplier and confirm what drug md-powder is referring to before you go any farther in this transaction.
Feel free to PM me with any questions or concerns.