We're talking millionths of a gram here. As I understand it, most of that has been metabolized even before the first trails appear. Certainly thirty years ago there wasn't any test to detect it apart from the dilated pupils during the, ah, episode.
Oddly enough I do know a reliable source, although I'm not disposed to avail myself of it: that's a younger person's game (or so I conclude on the basis of my cousin Ernie's accounts, lacking as I do, of course, any firsthand experience of these exotic indole compounds whatsoever).
The video was kinda crude, but hearing Atom Heart Mother again after so many years brought a smile to my craggy features.
cordially,