I've never myself tried alchem's nicselect (yet!), but I've been looking at a bunch of their coas, and as Kurt previously mentioned, then they're "crazy pure"!
About 10 times better than usp requirements for many of the contaniments, and about 8 times better than ph.eur standards(EP).
I think its really strange that such exceptionally clean nic can have such alkaloid or kerosene taste still, but oh well, I of course believe the observations many of you posted previously in this thread. Allthough it seems to have been a little better recently, according to e.g. Jimi, but still not "neutral" like chemnovatic, which sorta should be expected from such coa's.