Hmm I've been thinking about this a lot lately, specifically about the synthesis of LSD and what possible impurities could result from it. Most people who have at some point in their lives worked with pure crystal (not just chinacat, but older folks I know irl) confirm that there are different grades based on quality which were differentiated by color. So there was Amber and Lavender and all of that. It seems like the main impurity in all of these was something black-colored, as the range of crystal-quality follows the color line from darker to lighter shades.
I think one thing that'd be worth investigating is the other byproduct of Ergotamine hydrolysis. For the non-chemistry literate (and I'm not a chemist by any means, I just have a bit of interest in it and knowledge somewhere above a layperson but undoubtedly below a college grad):
Most of the LSD in the US is produced from diverted Ergotamine tartrate (see:
http://www.fas.org/irp/agency/doj/dea/product/lsd/lsd-5.htm). The molecular diagram of ergotamine looks like this:
while D-(+)-Lysergic acid looks like this:
Notice that the Lysergic acid is part of the Ergotamine molecule. Ergotamine is like lysergic acid + a lot of other stuff added on. When you perform an alkaline
hydrolysis on Ergotamine, the lysergic acid part is essentially separated from
the "other" part. I'm thinking that this mysterious "other" part could be the
contaminant, as I can't think of any other chemicals used that would form the
"nasty black stuff" which ex-LSD printers and hippies alike claim is the source
of LSD impurity.
I'm gonna post back later tonight or maybe tomorrow. I need to do a little pen-and-paper work to see exactly what this "other" part is, and whether it could be present in the clandestine lysergic acid, how it would react, and what
the final product would look like.
This whole thing will also be interesting because it can give some insight into
what method underground LSD cooks use specifically for coupling the lysergic
acid with diethylamine. I've always wondered if they use the method described (though not invented) by Shulgin using POCl3 as a dehydrating reagent, or the
higher-yielding Peptide-coupling reagents (PyBOP, DCC, etc.), or the original Hofmann method. I could see arguments for all of them from a clandestine perspective (from a legitimate perspective, i.e. in an ideal world, the peptide coupling method is by far the best, both in terms of simplicity and yield).
For example, POCl3 isn't easy to order or prepare, but I suppose a clandestine
chemist would likely have the connections to procure all the chemicals he needs. With the Hofmann method, while it's far lower-yielding, it's a bit more OTC (i.e. forming anhydrous hydrazine is easier than cooking up a batch of Phosphoryl chloride).