There are test kits available that can show you what you have, including tests for fentanyl. It requires a bunch of different reagent tests if you bought a Myst

There are test kits available that can show you what you have, including tests for fentanyl. It requires a bunch of different reagent tests if you bought a Mystery Powder that you want to ID. But if you were after MDMA, for example, and bought what’s claimed to be MDMA, you can test it with a specific reagent to confirm whether it is that or not, then test it with a fentanyl test strip to show if it’s free of that contaminant. Dance Safe sets up tents at big festivals to do this kind of testing as a harm reduction service. They (and others) are trying to normalize the step of testing what you have before using it, and I think that’s a wise choice especially with fentanyl in the mix. I’d expect that with decriminalized use of “white powder” drugs, you’d see these kits become more readily available from smoke shops, maybe even pharmacies, instead of being something you have to search for online.