Kovac's reagent is a biochemical reagent consisting of
isoamyl alcohol
Isoamyl alcohol is a colorless liquid with the formula , specifically (H3C–)2CH–CH2–CH2–OH. It is one of several isomers of amyl alcohol (pentanol). It is also known as isopentyl alcohol, isopentanol, or (in the IUPAC recommended nomencla ...
,
para-dimethylaminobenzaldehyde (DMAB), and concentrated
hydrochloric acid
Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid
Acid strength is the tendency of an acid, symbol ...
. It is used for the diagnostical
indole test
Indole is an aromatic Heterocyclic compound, heterocyclic organic compound with the formula Carbon, C8Hydrogen, H7Nitrogen, N. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered pyrrole ring. Indole ...
, to determine the ability of the organism to split
indole
Indole is an aromatic heterocyclic organic compound with the formula C8 H7 N. 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 environmen ...
from the
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...
tryptophan
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 ...
. The indole produced yields a red complex with para-dimethylaminobenzaldehyde under the given conditions.
This was invented by the Hungarian physician Nicholas Kovacs and was published in 1928. This reagent is used in the confirmation of ''E. coli'' and many other pathogenic microorganisms.
See also
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; som ...
is similar but uses
ethyl alcohol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a hyd ...
or
1-propyl alcohol.
References
2. Kovacs, N. (1928): Eine vereinfachte Methode zum Nachweis der Indolbildung durch Bakterien. Zeitschrift für Immunitätsforschung und Experimentelle Therapie, 55, 311.
Chemical tests
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