With any luck an actual chemist will be able to answer your question with more certainty, but until they get here, I'll take a stab at it: if it's pure alprazolam (as pure as you're going to get without a molecular sieve or something), and it's soluble in the solute you dumped it in, then my understanding is that the only way you'd end up with clumps on the bottom is if you supersaturated the solution. But I think it's obvious when that's the case because it doesn't dissolve at all, it just acts as though it weren't even soluble in the substance to begin with.So if I'm right -- and I hope I am, but it's a big if -- your clumps have to be propylene glycol and not alprazolam.