The problem with a simple cold water extraction is that the portion of the bead husks that does dissolve will cause the Adderall
to form a sticky pile of gunk when everything dries out. There's a data sheet on Adderall XR that provides its composition, but if I recall correctly it didn't mention the composition of the beads. If you can find anything on that, I'm sure an extraction can be worked out. I'll look when I get home.
Anyway, you could do an acid/base extraction to get a pretty pure amphetamine
salt, but that's more complex than a simple purification using only solvents.