Marquis reagent is used as a simple spot-test to presumptively identify alkaloids as well as other compounds. It is composed of a mixture of formaldehyde and concentrated sulfuric acid, which is dripped onto the substance being tested. The United States Department of Justice 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.
History Marquis reagent was first discovered and tested in 1896 by pharmacologist Eduard Marquis (1871–1944), then a student of Rudolf Kobert at the University of Dorpat (in Tartu, Estonia).Toxicology. Volume 2 : mechanisms and analytical methods — New York, New York; San Francisco, California : Academic Press, 1961 — p. 247. The reagent was described by Marquis in his Master of Pharmacy dissertation in 1896Marquis, Eduard. Über den Verbleib des Morphin im tierischen Organismus. Magister Dissertation 1896, Jurjew, Arb. Der Pharm. Inst. zu Dorpat 15, 117 (1896);Pharmazeutische Zentralhalle für Deutschland., 814 (1896);Pharmazeutische Zeitschrift für Russland. 38, 549 (1896). and subsequently named after him.
The reagent should be stored in the freezer for maximum shelf life.
It is the primary presumptive test used in Ecstasy reagent testing kits. It can also be used to test for such substances as opiates (e.g. codeine, heroin), and phenethylamines (e.g. 2C-B, mescaline).
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. + Marquis reagent test analysis Substance Color Time (s) Notes MDMA or MDA purple to black 0–5 May have dark purple tint Amphetamine, or methamphetamine orange to brown 0–5 May have a brown tint 2C-B yellow to green 5–10 Color may change from initial result DXM gray to black 15–30 Initially no change; takes much longer to reach black than MDMA
+ Final colors produced by Marquis Reagent with various substances Substance Color βk-2C-B Bright orange 30min 2C-B Green-yellow 30min 2C-I Green-yellow 30min 2,5-Dimethoxy-4-bromoamphetamine (DOB) Olive green – yellow 2-FMA Rapidly fizzes and dissolves. Colourless/light yellow 25I-NBOMe Orange 25C-NBOMe Clear, Transparent 25B-NBOMe Dark green 4F-MPH Transparent, no reaction 5-EAPB Purple to black 5-MeO-MiPT Clear/light brown Aspirin Pink > deep red Adrafinil Deep reddish orange – dark reddish brown Benzphetamine Deep reddish brown Benzylpiperazine(BZP) Clear (fizzes) Buprenorphine Pinkish violet Butylone Yellow Chlorpromazine Deep purplish red Codeine Very dark purple Caffeine Transparent, no change Cocaine Transparent, no change d-Amphetamine Strong reddish orange – dark reddish brown d-Methamphetamine Deep reddish orange – dark reddish brown Diacetylmorphine (Heroin) Deep purplish red Dimethoxy-4-amylamphetamine (DMAA) No color change (fizzes) Dimethyltryptamine (DMT) Orange Diphenhydramine (DPH) Yellow/orange > brown Dimethoxymethamphetamine HCL (DMMA) Moderate olive Doxepin Blackish red Dristan Dark grayish red Exedrine Dark red LSD Clear (no reaction), charring of paper may occur Methoxetamine Slow pink 3,4-Methylenedioxyamphetamine (MDA) Dark purple – black Methylenedioxy-N-ethylamphetamine (MDEA) Dark purple – black Methylenedioxymethamphetamine (MDMA) Dark purple – black Methylenedioxypropylamphetamine (MDPR) Dark purple – black Methylone (M1/bk-MDMA/MDMC) Yellow Methylenedioxypyrovalerone (MDPV) Yellow Pethidine/Meperidine Deep brown Mescaline Strong orange Methadone Light yellowish pink Methylphenidate Moderate orange yellow Methylene Blue Dark green Modafinil Yellow/orange – brown Morphine Deep purplish red Opium Dark grayish reddish brown Oxycodone Pale violet Propoxyphene Blackish purple Sugar Dark brown
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 Dille–Koppanyi reagent Folin's reagent Froehde reagent Liebermann reagent Mandelin reagent Mecke reagent Simon's reagent Zwikker reagent
References
External links Marquis reagent colors list, very comprehensive DHPedia - Marquis reagent: A comprehensive list of colour reactions with photos. Archived from the original on November 12, 2020.