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Discussion in 'Wiki Articles' started by NeuroChi, Jun 29, 2011.

  1. NeuroChi

    NeuroChi is not his mind Platinum Member & Advisor

    Reputation Points:
    Dec 18, 2007
    from earth
    The Marquis reagent is one of many drug identification reagents. It changes color in the presence of a compound in a predictable fashion and can be used to help infer the potential identity of a compound.

    Introduction To The Marquis Reagent

    The Marquis reagent is used to identify aromatic compounds. The coloration is due to a compound formed by condensation of multiple drug molecules. The obtained color is therefore related to the nature of the tested drug. The coloration is distinct between classes of drugs, for example between opiates and amphetamines. However, the reagent fails to unambiguously distinguish between two drugs in the same class, as the colorations may differ only by a slight shade. Therefore, multiple tests are sometimes required to efficiently identify a compound.

    Its advantage is that it can test for phenethylamines like 2C-x and DXM. Tests for: MDxx, (meth)amphetamine, 2C-x, DOx, DXM. It will also react with aspirin, some opiates, LSD, mescaline, methylphenidate and sugar.

    Testing with Marquis Reagent

    One can apply a few drops of the Marquis reagent to a sample of the compound on glass or ceramic. Be careful with test regents, they can be corrosive. Handle in a well ventilated area, gasses can emerge from the reaction.

    Observe the color change. Compare with chart below. [1]


    Known Color Changes with Marquis Reagent

    Column 1 Column 2
    Aspirin powder Deep red
    Benzphetamine HCl Deep reddish brown
    Chlorpromazine HCl Deep purplish red
    Codeine Very dark purple
    d-Amphetamine HCl to Strong reddish orange to Dark reddish brown
    d-Methamphetamine HCl Deep reddish orange to Dark reddish brown
    Diacetylmorphine HCl Deep purplish red
    Dimethoxy-meth HCl Moderate olive
    Doxepin HCl Blackish red
    Dristan powder Dark grayish red
    Exedrine powder Dark red
    LSD Olive black
    MDA HCl Black
    Meperidine HCl Deep brown
    Mescaline HCl Strong orange
    Methadone Light yellowish pink
    Methylphenidate Moderate orange yellow
    Morphine monohydrate Very deep reddish purple
    Opium Powder Dark grayish reddish Brown
    Oxycodone HCl Pale violet
    Propoxyphene HCl Blackish purple
    Sugar crystals Dark brown

    Making Marquis reagent

    Carefully add 100 mL of concentrated sulfuric acid to 5 mL of 40 percent
    formaldehyde (v:v, formaldehyde:water).[2]

    Danger of the Marquis Reagent

    1. Formaldehyde - TOXIC. May cause cancer. May cause heritable genetic damage. Toxic by inhalation, in contact with skin, and if swallowed. Causes burns. May cause sensitization by inhalation and skin contact. Readily absorbed through skin.L achrymator.Combustible. Target organs: eyes, kidneys. Wear suitable protective clothing and gloves.[2]

    2. Sulfuric acid - OXIDIZER, ACID, TOXIC, CORROSIVE. Liquid and mist
    cause severe burns to all body tissue. May be fatal if swallowed. Harmful if inhaled.
    Inhalation may case lung damage. Do not get liquid in eyes, on skin, or clothing. Wash thoroughly after handling. Avoid breathing vapors. Use with adequate ventilation. Do not add water to contents while in container because of violent reaction. Store in tightly closed container. Wear suitable protective clothing and gloves.[2]

    How the Marquis Reagent Works

    The Marquis reaction proceed by the condensation of drug molecules, yielding carbocations or larger unsaturated compounds which are colored. The reaction is selective toward activated aromatic cycles.

    General mechanism

    The drug molecule (1) undergo an electrophylic substitution by the protonated formaldehyde (2). The carbocation (3) obtained reacts with another drug molecule yielding a dimer (4). The dimer is subsequently oxidized (concentrated sulfuric acid behaves as an oxidizer) to give a stabilized carbocation (5). This last compound is colored and is responsible for the color observed.

    The regioselectivity of the addition of formaldehyde is determined by the usual selectivity rules for electrophilic substitutions.


    The previous mechanism must be refined for each compound. Below are given two examples for which the mechanisms have been elucidated.


    The reaction in the case of morphine differs sligthly from the previous scheme since two formaldehyde molecules (in red) are involved in the condensation, thus forming a cycle. Subsequent oxidization of the cycle leads to the formation of the purple/violet carbocation.[3]



    The case of methamphetamine fits perfectly with the general mechanism given above. The colored compound and produces an orangish color[3].There is also a possibility of condensation in the ortho position. However, the latter is much more strained and thus the amount produced is far less inferior to that of the depicted carbocation, leading to less polymerization and thus a clearer color.


    Additional notes

    The previous examples given show an unambiguous colored product. However, this is not always the case. For many molecules, there are multiple potential condensation sites, therefore leading to multiple colored compounds. Polymerization can also occur if the aromatic cycles are sufficiently reactive (for example with MDMA).

    In such cases, the compound tested will give a dark brown or black coloration, resulting from the multiple different absorption wavelengths. This situation is the same as when mixing many paints of different colors: the resulting mixture is dark brown.

    The color obtained depends on the composition of the starting reagent. Pre-made kits availabe over the internet are prepared the same way and thus the results from these tests are reproductible. However, hand made reagents will have some small variations in their composition, leading to slightly different results (shades of color will vary). For example a reagent containing more formaldehyde will induce more polymerization thus a darker coloration.

    The presence of adulterants in the tested product may also affect the resulting coloration:
    - Firstly, the adulterants may react by themselves with the reagent adding their own coloration to the result.
    For example if some sugars are present (lactose for example), they will caramellize in the presence of sulfuric acid, thus producing a brown coloration. This is not the result of a marquis reaction, but only the reaction of the sugar with sulfuric acid.
    Another case is if some aromatic compounds are present (like acetaminophen), they will undergo a marquis reaction, therefore yielding their own coloration which will superpose to give the resulting coloration.
    - Secondly, the adulterants may react with the drug forming cross condensed products yielding a different color.

    Compounds tested with Marquis Reagent

    The following is a list of compounds tested by Drugs Forum members with the Marquis reagent.

    Verified refers to whether or not the compound was verified by a third party lab (ie. GC/MS results confirm).

    Color refers to the best description of the color either by image upload or user(s) description. Please see the thread linked for more information.

    Compound Verified? Color Other notes
    2C-T-7 [1] no light orange progressing to orange
    25B-NBOMe [1] no first yellow then going to light green
    25C-NBOMe [1] no start's orange going to golden and then to green
    25I-NBOMe [1] no dark green crystalline and white
    25I-NBOMe [2] no dark green/brown very white but more dusty
    25I-NBOMe [3] no dark green yellowish and lumpy
    25I-NBOMe [4] no dark green/brown white dusty and maybe freebase
    4-FA [1] no Bright Yellow
    4-FA [2] no Bright Yellow
    4-FA [3] no Light Orange user believes this is 4-FA
    4-FMA [1] no Yellow/ dark yellow. Spot of pink. user comments this compound is barely active in high doses
    5-APB [1] no between brown red and violet
    6-APB [1] no Dark Brown user describes this compound as supposedly 6-APB, though very impure
    6-APB [2] no Purple Reacts as should with EZ test MCPP test which also tests for 6-APB
    DOC [1] no fizzing and bubles, then green
    DOC [2] no Deep Green consistent with results from other users light pink with a fine powder texture
    DOC [3] no Deep Green consistent with results from other users yellow powder more lumpy than [2]
    DPT no Yellow, Olive
    JWH-073 [1] no dark brown
    JWH-081 [1] no orange > orange/green/brown
    JWH-250 [1] no red/orange
    MDPV [1] no Orange no rxn to Simons or Robadope, implies tertiary amine (MDPV)
    MDPV [2] no Orange no rxn to Simons or Robadope, implies tertiary amine (MDPV)
    Methylone [1] no Yellow consistent with EZ Test results
    Methylone [2] no Orange consistant with EZ test result
    Butylone [1] no Orange consistant with EZ test results
    Mephedrone [1] no pale yellow pure Mephedrone supposedly show no reaction
    Mephedrone [2] no pale yellow pure Mephedrone supposedly shows no reaction
    Naphyrone [1] no Bright Orange rxn to Simons, implies secondary amine (not Naphyrone)
    Benzo-Fury Pellet [1] no Purple


    1. ^EZ Test Marquis: The classic test for ecstasy. EZ Test. Located here: http://www.eztest.com/dir2/ez-test-marquis-the-classic-test-for-ecstasy. (Accessed July 29, 2011).
    2. ^ a b c dReagent A.5. Colour Test Reagents-Kits for Preliminary Identification of Drugs of Abuse. National Institute of Justice.
    3. ^ a bChemistry and Reaction Mechanisms of Rapid Tests https://drugs-forum.com/forum/loc...id=17&id=12434

    [CAT]Drug Testing Reagents[/CAT]

    Attached Files:

    Last edited by a moderator: Sep 10, 2017
  2. NeuroChi

    NeuroChi is not his mind Platinum Member & Advisor

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    Dec 18, 2007
    from earth
    Just started up articles for Marquis, Mandelin, and Mecke. All three need review, I'll be checking over for any errors but any guidance is appreciated.

    I'd also like to expand the Compounds tested section, please post or add yourself if you can test a compound, or if you find one elsewhere at DF.

    Also very important is an understanding of how the reagents work, how the color change takes place due to chemical composition of the compound. Chemists - please contact me if you could help add this section. This would greatly enhance the functionality of these articles to better predict how new compounds should react with these reagents.
  3. kitchen chemist

    kitchen chemist Newbie

    Reputation Points:
    Feb 17, 2012
    26 y/o from ireland
    just tested some steroids, DBOL/dianabol - methandrostenolone
    went bright red instantly, then dark red

    also tested Phenethylamine (PEA), went red in the same way as methamphetamine
  4. Tha_Stiffmeister

    Tha_Stiffmeister Silver Member

    Reputation Points:
    Dec 5, 2006
    from The Netherlands

    link whive some usefull information for your research

  5. User-126494

    User-126494 Platinum Member

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    Oct 30, 2009
    from earth
    Reworked the footnotes, and put a H=1 introduction at the top so the TOC would be generated in the correct location.

    Could someone verify for me that I have the footnotes in the correct place. I think they are, but a second set of eyes would be helpful.

    Be well...
  6. Tha_Stiffmeister

    Tha_Stiffmeister Silver Member

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    Dec 5, 2006
    from The Netherlands
    @ wanderer; Footnotes are reworked correct, thanks verry helpful
  7. NeuroChi

    NeuroChi is not his mind Platinum Member & Advisor

    Reputation Points:
    Dec 18, 2007
    from earth
  8. Docta

    Docta Idiot Savant Palladium Member Donating Member

    Reputation Points:
    Dec 19, 2005
    from Australia
    There are some very nice images that I'd like to integrate but they need to be cropped and re-sized so anybody doing updates please note,

    Do not link in the images I'll attach them here and edit them in.
  9. John_bob

    John_bob Titanium Member Donating Member

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    Oct 10, 2010
    from earth
    The mechanism section has been filled