Marquis reagent

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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.[1]: 12  Different compounds produce different color reactions. Methanol may be added to slow down the reaction process to allow better observation of the colour change.[citation needed]


Marquis reagent was first discovered in 1896[2] and described by the Russian (Estonian) pharmacologist, Eduard Markus (1871–1944) (Russian: Эдуард Маркус)[3] in his magister dissertation in 1896;[4] and named after him,[5] and was tested for the first time at the University of Dorpat. The reagent should be stored in the freezer for maximum shelf life[6]

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:


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.[7]

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[7]
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[1]: 3–6 [8]
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[citation needed]
25I-NBOMe Orange[citation needed]
25C-NBOMe Clear, Transparent[citation needed]
25B-NBOMe Dark green[citation needed]
4F-MPH Transparent, no reaction[citation needed]
5-EAPB Purple to black[citation needed]
5-MeO-MiPT Clear/light brown[9]
Aspirin Pink > deep red[10][11][12]
Adrafinil Deep reddish orange – dark reddish brown[citation needed]
Benzphetamine Deep reddish brown
Benzylpiperazine(BZP) Clear (fizzes)
Buprenorphine Pinkish violet
Butylone Yellow[8]
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[13]
Dimethoxymethamphetamine HCL (DMMA) Moderate olive
Doxepin Blackish red
Dristan Dark grayish red
Exedrine Dark red
LSD Olive black
Methoxetamine Slow pink[8]
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[14]
Morphine Deep purplish red
Opium Dark grayish reddish brown
Oxycodone Pale violet
Propoxyphene Blackish purple
Sugar Dark brown


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.[15]

See also[edit]


  1. ^ a b "Color Test Reagents/Kits for Preliminary Identification of Drugs of Abuse" (PDF). Law Enforcement and Corrections Standards and Testing Program. July 2000. Retrieved 24 July 2011.
  2. ^ Toxicology. Volume 2 : mechanisms and analytical methods — New York, New York ; San Francisco, California : Academic Press, 1961 — p. 247.
  3. ^ Каталог диссертаций Дерптского Университета с 1811 по 1914 гг. Archived 4 March 2016 at the Wayback Machine // Ин-т экспериментальной медицины
  4. ^ Markus, 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).
  5. ^ Юрген Торвальд Сто лет криминалистики — М: Прогресс, 1974
  6. ^ "FAQ". ElevationChemicals. Retrieved 2 December 2018.
  7. ^ a b "Reagent Testing Instructions". Retrieved 21 December 2016.
  8. ^ a b c Morris, Jeremiah. Color Tests and Analytical Difficulties with Emerging Drugs (PDF). Johnson County Sheriff’s Office Criminalistics Laboratory: NIST. p. 36. Retrieved 10 May 2014.
  9. ^ "EcstasyData 5-MeO-MiPT". EcstasyData.
  10. ^ "Controlled Substances Procedures Manual" (PDF). Virginia Department of Forensic Science. 2013. Archived from the original (PDF) on 13 August 2013. Retrieved 6 August 2013.
  11. ^ "Color Test Reagents/Kits for Preliminary Identification of Drugs of Abuse" (PDF). Law Enforcement and Corrections Standards and Testing Program. July 2000. Retrieved 24 July 2011.
  12. ^ O’Neal, C. L.; Crouch, D. J.; Fatah, A. A. (2000). "Validation of twelve chemical spot tests for the detection of drugs of abuse". Forensic Science International. 109 (3): 189–201. doi:10.1016/S0379-0738(99)00235-2. PMID 10725655.
  13. ^ Johns, S. H.; Wist, A. A.; Najam, A. R. (1 July 1979). "Spot Tests: A Color Chart Reference for Forensic Chemists" (PDF). Journal of Forensic Sciences. 24 (3): 631. doi:10.1520/JFS10882J. S2CID 68755072. Archived from the original (PDF) on 25 February 2020.
  14. ^ Morris, Jeremiah (2004). "Analytical Profile of Modafinil" (PDF). Microgram Journal. 3 (1–2): 28. Retrieved 9 October 2013.
  15. ^ Lancashire, Robert J. (13 October 2011). "Unit 9: Crime - Reagent Kits". University of the West Indies, Mona Campus. Retrieved 17 March 2014.

External links[edit]