Is Liebermann reagent reliable?
This version has been translated from Polish and links to the relevant test kits have been added. In a life-threatening situation call 112. This article is informational and serves harm reduction. It does not encourage the use of psychoactive substances and does not replace medical advice.
Liebermann is reliable, and it is the most useful exclusion reagent in the set. Liebermann rules out phenacetin, ephedrine, lidocaine, levamisole, methamphetamine, cathinones and the secondary coca alkaloids, which is a longer list of adulterants than any other single reagent covers. For cocaine in particular it does more work than the reagent that confirms the cocaine.
The orange result
With pure cocaine, liebermann should stay yellow. If it turns orange, that indicates secondary coca alkaloids such as benzoylecgonine, methylecgonidine or tropacocaine, which are not adulterants at all but processing products from the plant. They are not dangerous in themselves and they do cause false positives elsewhere, so an orange liebermann is a signal to look more closely rather than a reason to throw a sample away.
Those alkaloids turned up in 71 of the 767 cocaine samples European labs published, so this is not a rare reading.
False positives from coca alkaloids · How to test cocaine purity · Cocaine and cuts kit, 31,40 EUR
Where it is weaker
It is a broad reagent, which is its strength for exclusion and its weakness for confirmation, since a great many compounds produce a dark result and a dark result on its own does not identify anything. Use it to narrow the field and something else to name what is left.
Liebermann reagent, 7.30 EUR · Liebermann instructions · Cocaine and cuts kit
Questions?
What does an orange liebermann mean?
Secondary coca alkaloids, most likely. Not dangerous, but worth investigating further.
Is it good for identification?
It is better at exclusion. Pair it with morris for cocaine or marquis for the MDxx compounds.
Does it detect levamisole?
It helps exclude it. Direct identification of levamisole needs a plate.