[alessandru]

you would go to where trustworthy people are selling it. you would have your friend try it first if purchased from random street dealer. i think many of these get confused in the street, like how would you know it is true lsd and not some other research chemical?

in america there are pockets of psychadelic support that would provide clean sources, you'd maybe network with them through campus norml groups, or that cool chemistry TA. these people have zero incentive to sell you something different or contaminate it with anything (more work).

when it is dosed correctly, you can take a small dose of lsd and see if it is the effect you recognize or something else. definitely just do some homework to make sure that it can be trusted.