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 Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular fo ...

, 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 federal executive department of the United States government tasked with the enforcement of federal law and administration of justice in the United Stat ...

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 Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is ...

may be added to slow down the reaction process to allow better observation of the colour change. It was first discovered in 1896Toxicology. 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 University of Tartu (UT; et, Tartu Ülikool; la, Universitas Tartuensis) is a university in the city of Tartu in Estonia. It is the national university of Estonia. It is the only classical university in the country, and also its biggest ...

. The reagent should be stored in the freezer for maximum shelf life It is the primary

presumptive test Presumptive tests, in medical and forensic science, analyze a sample and establish one of the following: #The sample is definitely not a certain substance. #The sample probably is the substance. For example, the Kastle–Meyer test will show eith ...

used in Ecstasy

reagent testing 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 a ...

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 antagoni ...

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 ...

heroin Heroin, also known as diacetylmorphine and diamorphine among other names, is a potent opioid mainly used as a recreational drug for its euphoric effects. Medical grade diamorphine is used as a pure hydrochloride salt. Various white and bro ...

), 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 so ...

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.

References

External links

Drug Testing Kit FAQ - Marquis reagent colors list, very comprehensive. Erowid.org

DHPedia - 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

Results

Mechanism

See also

References

External links