Color tests for the detection of hallucinogenic drugs have been developed. This was shown in 1973, when twenty different hallucinogens were applied to chromatography plates and then sprayed with one of various chromogenic reagents. The formation of a color band was dependent on the electron-donating properties of the drug molecule.
“As would have been expected, the polycyclic and consequently more “electron-rich” hallucinogens, such as the harmine derivatives 6-methoxyharmalan and harmaline gave stronger colors than the simple monocyclic beta-phenylethylamines derivatives [such as mescaline, TMA, DOM, or 2,3-dimethoxy-amphetamine].” (Heacock,R.A. 1973)The tryptamine derivatives DMT, methyltryptamine, and alpha-methyltryptamine reacted strongly with tetracyanoethylene (TCNE), an electron acceptor used as a color test reagent. Beta-carboline derivatives 6-methoxyharmalan and harmaline gave intense colors with TCNE and all electron acceptors studied. Ibogaine and LSD were easily detected with TCNE (Heacock and Forrest, 1973). The chromatographic evidence suggests that the broadly defined class of hallucinogens function as electron donors.
Erspamer was the first scientist to study serotonin in depth. His technique involved staining with the Ehrlich reaction to test for the presence of serotonin, which he called enteramine. Also referred to as Van Urk's reagent, Ehrlich's reagent is 2% dimethylaminobenzaldehyde in hydrochloric acid. It forms a purple charge-transfer complex with serotonin as well as most indoles and chlorpromazine. A purple charge-transfer complex is formed when Ehrlich's reagent is mixed with LSD. Psilocybin gives a violet color characteristic of indoles in the Van Urk reaction (A. Hofmann, 1961).
Chlorpromazine also participates in the Van Urk reaction. The Chlorpromazine-Van Urk complex has an absorption band at 520 nm, which is identical to that of the LSD-Van Urk complex. Chlorpromazine is an electron donor, so it is not surprising that chlorpromazine would form a charge-transfer reactions with the Van Urk reagent which functions as electron acceptor.
"The procedure allows for a simple, rapid, and accurate determination of small quantities of chlorpromazine." (Murty,B.S. 1970)There are many electronic similarities between LSD and chlorpromazine. LSD and chlorpromazine both have a low transport number, and they both react with Van Urk reagent to produce a macromolecular complex with an absorption peak at 520 nm. The similarites between LSD and chlorpromazine could be related to their common anthracene-like structure, known to have exceptional electron-donating and electron-receiving properties. Though the drug effects are dissimilar, with chlorpromazine being considered to be an antipsychotic drug and LSD being considered to be one of the most powerful hallucinogen drugs known to man, they do cause a distinguishable change in awareness and may be able to provide some information about consciousness alteration by their mechanism.
Heacock R. A. and J. E. Forrest (1973). The use of electron-acceptor reagents for the detection of some hallucinogens. Journal of Chromatography 78, 240-250. 10.1016/S0021-9673(01)99063-6
HOFMANN A. (1961). Chemical pharmacological and medical aspects of psychotomimetics. Journal of experimental medical sciences 5, 31-51.Murty B. S. and R. M. Baxter (1970). Spectrophotometric determination of chlorpromazine in pharmaceutical dosage forms. Journal of pharmaceutical sciences 59, 1010-1011. 10.1002/jps.2600590721