LSD does not have a vapor pressure high enough to be detectable by dogs. even the most sensitive gas sensing instruments cannot detect large chemicals (LSD is a large molecule by illicit drug standards) like LSD.
Morphine itself is pretty difficult to detect. Heroin is extremely easy, because heroin continuosly releases acetic acid (vinegar) and makes it incredibly easy to smell. Cannabis is detected by the smell of the terpenoids (which are the compounds responsible for the smell). THC itself is not detectable by dogs.
I am not 100% sure if morphine, by itself, could be detected. This would only be relevant to someone who was smuggling pharmaceutical pills, because any other sample of illicit morphine (Opium or heroin or poppy pods) will come along with OTHER STUFF that CAN be detected.
in general, most illicit drugs are detectable by dogs inherently (by this I mean the dog actually smells the drug itself). the rest are detected by smelling by products, typical impurities, or some other form of "extra chemical" that is not necessarily present in pure samples (which are exceedingly rare).
Because LSD is often found as pure chemical, either in liquid or blotter form, it is extremely difficult to detect with drug dogs.
Fentanyl (china white) is another drug that is not detectable by itself, though impurities may indicate its presence to drug dogs.
much of the work of drug dog trainers is working with DEA laboratory technicians to determine how/which chemical to use to identify a specific type of drug.
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http://www.wired.com/threatlevel/2011/06/silkroad/
Jeg har ikke noen kilder på om det stemmer eller ikke, men virker logisk at LSD er vanskelig å lukte seg frem til.