Ehrlich's reagent

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p-DMAB: the active ingredient in Ehrlich's reagent Para-Dimethylaminobenzaldehyde.png
p-DMAB: the active ingredient in Ehrlich's reagent

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.

Contents

The Ehrlich reagent works by binding to the C2 position of two indole moieties to form a resonance stabilised carbenium ion compound. [1]

Medical testing

Ehrlich's reagent can be used to test for the presence of LSD. Upon reaction, the Ehrlich's reagent turns to purple indicating the presence of LSD. LSD Ehrlich reagent test.jpg
Ehrlich's reagent can be used to test for the presence of LSD. Upon reaction, the Ehrlich's reagent turns to purple indicating the presence of LSD.

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 ergoloids (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]

Preparation

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:

See also

Related Research Articles

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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.

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<span class="mw-page-title-main">Psychedelic drug</span> Hallucinogenic class of psychoactive drug

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<span class="mw-page-title-main">Indole alkaloid</span> Class of alkaloids

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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.

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<span class="mw-page-title-main">Indole</span> Chemical compound

Indole is an aromatic, heterocyclic, organic compound with the formula C8H7N. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered pyrrole ring. Indole is widely distributed in the natural environment and can be produced by a variety of bacteria. As an intercellular signal molecule, indole regulates various aspects of bacterial physiology, including spore formation, plasmid stability, resistance to drugs, biofilm formation, and virulence. The amino acid tryptophan is an indole derivative and the precursor of the neurotransmitter serotonin.

<i>p</i>-Dimethylaminocinnamaldehyde Chemical compound

p-Dimethylaminocinnamaldehyde (DMACA) is an aromatic hydrocarbon. It is used in an acidic solution to detect indoles.

<span class="mw-page-title-main">Substituted tryptamine</span> Class of indoles

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References

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  10. Sunshine, Irving (1969). Handbook of analytical toxicology. Chemical Rubber Co. p. 408. 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.
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