Marquis reagent is used as a simple spot-test to presumptively identify
alkaloids
Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar ...
as well as other compounds. It is composed of a mixture of
formaldehyde
Formaldehyde ( , ) ( systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...
and concentrated
sulfuric acid, which is dripped onto the substance being tested. The
United States Department of Justice
The United States Department of Justice (DOJ), also known as the Justice Department, is a United States federal executive departments, federal executive department of the United States government tasked with the enforcement of federal law and a ...
method for producing the reagent is the addition of 100 mL of concentrated (95–98%) sulfuric acid to 5 mL of 40% formaldehyde.
Different compounds produce different color reactions.
Methanol may be added to slow down the reaction process to allow better observation of the colour change.
It was first discovered in 1896
[Toxicology. Volume 2 : mechanisms and analytical methods]
— New York, New York ; San Francisco, California : Academic Press, 1961 — p. 247. and described by the Russian (Estonian) pharmacologist,
Eduard Marquis (1871–1944) (russian: Эдуард Маркус) in his magister dissertation in 1896; and named after him, and was tested for the first time at the
University of Dorpat. The reagent should be stored in the freezer for maximum shelf life
It is the primary
presumptive test used in
Ecstasy
Ecstasy may refer to:
* Ecstasy (emotion), a trance or trance-like state in which a person transcends normal consciousness
* Religious ecstasy, a state of consciousness, visions or absolute euphoria
* Ecstasy (philosophy), to be or stand outside o ...
reagent testing kits. It can also be used to test for such substances as
opiate
An opiate, in classical pharmacology, is a substance derived from opium. In more modern usage, the term ''opioid'' is used to designate all substances, both natural and synthetic, that bind to opioid receptors in the brain (including antagonist ...
s (e.g.
codeine
Codeine is an opiate and prodrug of morphine mainly used to treat pain, coughing, and diarrhea. It is also commonly used as a recreational drug. It is found naturally in the sap of the opium poppy, ''Papaver somniferum''. It is typically use ...
,
heroin), and
phenethylamine
Phenethylamine (PEA) is an organic compound, natural monoamine alkaloid, and trace amine, which acts as a central nervous system stimulant in humans. In the brain, phenethylamine regulates monoamine neurotransmission by binding to trace am ...
s (e.g.
2C-B
2C-B (4-Bromo-2,5-dimethoxyphenethylamine) is a psychedelic drug of the 2C family. It was first synthesized by Alexander Shulgin in 1974. In Shulgin's book '' PiHKAL'', the dosage range is listed as 12–24 mg. As a recreational drug, 2C-B is ...
,
mescaline
Mescaline or mescalin (3,4,5-trimethoxyphenethylamine) is a naturally occurring psychedelic protoalkaloid of the substituted phenethylamine class, known for its hallucinogenic effects comparable to those of LSD and psilocybin.
Biological ...
).
The test is performed by scraping off a small amount of the substance and adding a drop of the reagent (which is initially clear and colorless). The results are analyzed by viewing the color of the resulting mixture, and by the time taken for the change in color to become apparent:
Results
Reagent test results develop very quickly and due to reactions with moisture and oxygen in air, any changes after the first 60 seconds should be discarded.
Mechanism
The colour change from morphine is proposed to be a result of two molecules of morphine and two molecules of formaldehyde condensing to the dimeric product which is protonated to the oxocarbenium salt.
See also
*
Drug checking
*
Drug test
A drug test is a technical analysis of a biological specimen, for example urine, hair, blood, breath, sweat, or oral fluid/saliva—to determine the presence or absence of specified parent drugs or their metabolites. Major applications of d ...
*
Dille–Koppanyi reagent
*
Folin's reagent
Folin's reagent or sodium 1,2-naphthoquinone-4-sulfonate is a chemical reagent used as a derivatizing agent to measure levels of amines and amino acids. The reagent reacts with them in alkaline solution to produce a fluorescent material that c ...
*
Froehde reagent
*
Liebermann reagent
*
Mandelin reagent
*
Mecke reagent
The Mecke reagent is used as a simple spot-test to presumptively identify alkaloids as well as other compounds. It is composed of a mixture of selenous acid and concentrated sulfuric acid, which is dripped onto the substance being tested.
The Unit ...
*
Simon's reagent
*
Zwikker reagent
References
External links
Drug Testing Kit FAQ - Marquis reagent colors list, very comprehensive. Erowid.orgDHPedia - Marquis reagent: A comprehensive list of colour reactions (inducing photographs of results){{Use dmy dates, date=March 2019
Chemical tests
Analytical reagents
Drug testing reagents