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.<ref name="NIJColorTest">Template:Cite web</ref>Template:Rp Different compounds produce different color reactions. Methanol may be added to slow down the reaction process to allow better observation of the colour change.Template:Citation needed
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).<ref>Template:Citation</ref><ref>Template:Citation</ref><ref>Template:Citation</ref><ref name=tox>Toxicology. Volume 2 : mechanisms and analytical methods — New York, New York; San Francisco, California : Academic Press, 1961 — p. 247.</ref> The reagent was described by Marquis in his Master of Pharmacy dissertation in 1896<ref>Marquis, 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).</ref> and subsequently named after him.
The reagent should be stored in the freezer for maximum shelf life.<ref>Template:Cite web</ref>
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.<ref name="Reagent test instructions"/>
| 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<ref name="Reagent test instructions">Template:Cite web</ref> |
| DXM | gray to black | 15–30 | Initially no change; takes much longer to reach black than MDMA |
| 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 yellowTemplate:Citation needed |
| 25I-NBOMe | OrangeTemplate:Citation needed |
| 25C-NBOMe | Clear, TransparentTemplate:Citation needed |
| 25B-NBOMe | Dark greenTemplate:Citation needed |
| 4F-MPH | Transparent, no reactionTemplate:Citation needed |
| 5-EAPB | Purple to blackTemplate:Citation needed |
| 5-MeO-MiPT | Clear/light brown<ref>Template:Cite web</ref> |
| Aspirin | Pink > deep red<ref name='Virginia'>Template:Cite web</ref><ref name="DOJmanual">Template:Cite web</ref><ref name="Validation">Template:Cite journal</ref> |
| Adrafinil | Deep reddish orange – dark reddish brownTemplate:Citation needed |
| Benzphetamine | Deep reddish brown |
| Benzylpiperazine(BZP) | Clear (fizzes) |
| Buprenorphine | Pinkish violet |
| Butylone | Yellow<ref name="morris" /> |
| 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<ref>Template:Cite journal</ref> |
| Dimethoxymethamphetamine HCL (DMMA) | Moderate olive |
| Doxepin | Blackish red |
| Dristan | Dark grayish red |
| Exedrine | Dark red |
| LSD | Clear (no reaction), charring of paper may occur <ref>Template:Cite web</ref> |
| Methoxetamine | Slow pink<ref name="morris" /> |
| 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<ref name='microgram2005'>Template:Cite journal</ref> |
| 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.<ref name='UWI Mina CHEM2402'>Template:Cite web</ref>
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.