Ehrlich's reagent or Ehrlich reagent is a reagent containing p-dimethylaminobenzaldehyde (DMAB) and thus can act as an indicator to presumptively identify indoles and urobilinogen. Several Ehrlich tests use the reagent in a medical test; some are drug tests and others contribute to diagnosis of various diseases or adverse drug reactions. It is named after Nobel Prize winner Paul Ehrlich who used it to distinguish typhoid from simple diarrhoea.
The Ehrlich reagent works by binding to the C2 position of two indole moieties to form a resonance stabilised carbenium ion compound. [1]
Ehrlich reagent can be used to detect urobilinogen, which can indicate jaundice or other liver-related issues.
A very common Ehrlich test is a simple spot test to identify possible psychoactive compounds such as tryptamines (e.g. DMT) and lysergamides (e.g. LSD). It gives a negative test-result for 25I-NBOMe and many other non-indole-related psychoactives. The reagent will also give a positive result for opium, because of the presence of tryptophan in natural opium. [3]
Pyridoxine, present in vitamin supplements, can give positive results to the Ehrlich test, showing a pink colour change. [4]
The reagent is prepared by dissolving 0.5 [5] –2.0 g of p–dimethylaminobenzaldehyde (DMAB) in 50 mL of 95% ethanol and 50 mL of concentrated hydrochloric acid [6] [7] and is best used when fresh. Other alcohols, such as 1-propanol, can also be used as well. [8]
The Ehrlich reagent is similar to a number of other indole tests:
N,N-Dimethyltryptamine is a substituted tryptamine that occurs in many plants and animals, including humans, and which is both a derivative and a structural analog of tryptamine. DMT is used as a psychedelic drug and prepared by various cultures for ritual purposes as an entheogen.
Lysergic acid diethylamide, commonly known as LSD, is a potent psychedelic drug that intensifies thoughts, emotions, and sensory perception. Often referred to as acid or lucy, LSD can cause mystical, spiritual, or religious experiences. At higher doses, it primarily induces visual and auditory hallucinations. LSD is not considered addictive, because it does not produce compulsive drug-seeking behavior. Using LSD can lead to adverse psychological reactions, such as anxiety, paranoia, and delusions. Additionally, it may trigger "flashbacks," also known as hallucinogen persisting perception disorder (HPPD), where individuals experience persistent visual distortions after use.
Psilocybin, also known as 4-phosphoryloxy-N,N-dimethyltryptamine (4-PO-DMT), and formerly sold under the brand name Indocybin, is a naturally occurring psychedelic prodrug compound produced by more than 200 species of fungi. Psilocybin is itself biologically inactive but is quickly converted by the body to psilocin, which has mind-altering effects similar, in some aspects, to those of other classical psychedelics. Effects include euphoria, hallucinations, changes in perception, a distorted sense of time, and perceived spiritual experiences. It can also cause adverse reactions such as nausea and panic attacks.
Tryptophan (symbol Trp or W) is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α-carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromatic beta carbon substituent. Tryptophan is also a precursor to the neurotransmitter serotonin, the hormone melatonin, and vitamin B3 (niacin). It is encoded by the codon UGG.
N,N-Dipropyltryptamine (DPT) is a psychedelic entheogen belonging to the tryptamine family. Use as a designer drug has been documented by law enforcement officials since as early as 1968. However, potential therapeutic use was not investigated until the 1970s. It is found either as a crystalline hydrochloride salt or as an oily or crystalline base. It has not been found to occur endogenously. It is a close structural homologue of dimethyltryptamine and diethyltryptamine.
Tryptamine is an indolamine metabolite of the essential amino acid tryptophan. The chemical structure is defined by an indole—a fused benzene and pyrrole ring, and a 2-aminoethyl group at the second carbon. The structure of tryptamine is a shared feature of certain aminergic neuromodulators including melatonin, serotonin, bufotenin and psychedelic derivatives such as dimethyltryptamine (DMT), psilocybin, psilocin and others.
5-MeO-MiPT is a psychedelic and hallucinogen of the tryptamine family. It used by some as an entheogen. It has structural and pharmacodynamic properties similar to the drugs 5-MeO-DiPT, DiPT, and MiPT. It is commonly used as a "substitute" for 5-MeO-DiPT because of the very similar structure and effects.
ALD-52, also known as 1-acetyl-LSD, has chemical structural features similar to lysergic acid diethylamide (LSD), a known psychedelic drug. Similarly, ALD-52 has been reported to produce psychoactive effects, but its pharmacological effects on humans are poorly understood. Given its psychoactive properties, it has been reported to be consumed as a recreational drug, and the purported first confirmed detection of the substance on the illicit market occurred in April 2016.
Urobilinogen is a yellow by-product of bilirubin reduction. It is formed in the intestines by the bacterial enzyme bilirubin reductase. About half of the urobilinogen formed is reabsorbed and taken up via the portal vein to the liver, enters circulation and is excreted by the kidney.
The indole test is a biochemical test performed on bacterial species to determine the ability of the organism to convert tryptophan into indole. This division is performed by a chain of a number of different intracellular enzymes, a system generally referred to as "tryptophanase."
AL-LAD, also known as 6-allyl-6-nor-LSD, is a psychedelic drug and an analog of lysergic acid diethylamide (LSD). It is described by Alexander Shulgin in the book TiHKAL. It is synthesized starting from nor-LSD as a precursor, using allyl bromide as a reactant.
Reagent testing is one of the processes used to identify substances contained within a pill, usually illicit substances. With the increased prevalence of drugs being available in their pure forms, the terms "drug checking" or "pill testing" may also be used, although these terms usually refer to testing with a wider variety of techniques covered by drug checking.
para-Dimethylaminobenzaldehyde is an organic compound containing amine and aldehyde moieties which is used in Ehrlich's reagent and Kovac's reagent to test for indoles. The carbonyl group typically reacts with the electron rich 2-position of the indole but may also react at the C-3 or N-1 positions. It may also be used for determination of hydrazine.
Indole is an organic compound with the formula C6H4CCNH3. Indole is classified as an aromatic heterocycle. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered pyrrole ring. Indoles are derivatives of indole where one or more of the hydrogen atoms have been replaced by substituent groups. Indoles are widely distributed in nature, most notably as amino acid tryptophan and neurotransmitter serotonin.
5-(2-Aminopropyl)indole is an indole and phenethylamine derivative with empathogenic effects. Its preparation was first reported by Albert Hofmann in 1962. It is a designer drug that has been openly sold as a recreational drug by online vendors since 2011.
p-Dimethylaminocinnamaldehyde (DMACA) is an aromatic hydrocarbon. It is used in an acidic solution to detect indoles.
Substituted tryptamines, or simply tryptamines, also known as serotonin analogues (i.e., 5-hydroxytryptamine analogues), are organic compounds which may be thought of as being derived from tryptamine itself. The molecular structures of all tryptamines contain an indole ring, joined to an amino (NH2) group via an ethyl (−CH2–CH2−) sidechain. In substituted tryptamines, the indole ring, sidechain, and/or amino group are modified by substituting another group for one of the hydrogen (H) atoms.
The Zwikker reagent is used as a simple spot-test to presumptively identify barbiturates. It is composed of a mixture of two solutions. Part A is 0.5 g of copper (II) sulfate in 100 ml of distilled water. Part B consists of 5% pyridine (v/v) in chloroform. One drop of each is added to the substance to be tested and any change in colour is observed.
1V-LSD, sometimes nicknamed Valerie, is a psychotropic substance and a research chemical with psychedelic effects. 1V-LSD is an artificial derivative of natural lysergic acid, which occurs in ergot alkaloids, as well as being an analogue of LSD. 1V-LSD has been sold online until an amendment to the German NpSG was enforced in 2022 which controls 1P-LSD and now 1cP-LSD, 1V-LSD and several other lysergamides.
2.03 g FeCI3. 6 H2O were dissolved in 500 ml water and 300 ml conc. H2SO4
p-DMAB-TS: To a cool soln of 65 ml H2S04 in 35 ml H2O, add 125 mg para-dimethylaminobenzaldehyde, dissolve, add 1-2 drops of FeCI3-TS.