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.: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. This is done by slowing down the polymerisation process.
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:
|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||orange 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|
|2C-B - 4-bromo-2,5-dimethoxyphenethylamine||Green-Yellow|
|2C-I - 2,5-dimethoxy-4-iodophenethylamine||Green-Yellow|
|2,5-Dimethoxy-4-bromoamphetamine (DOB)||Olive Green - Yellow|
|2-FMA||Rapidly fizzes and dissolves. Colourless/Light yellow|
|25C-NBOMe||Clear (No change)|
|25B-NBOMe||Dark Green|
|5-EAPB||Purple to Black|
|Adrafinil||Deep reddish orange - Dark reddish brown|
|Benzphetamine HCl||Deep reddish brown|
|Chlorpromazine HCl||Deep purplish red|
|Codeine||Very dark purple|
|Caffeine||Clear (no change)|
|Cocaine||Clear (No change)|
|d-Amphetamine HCl||Strong reddish orange - Dark reddish brown|
|d-Methamphetamine HCl||Deep reddish orange - Dark reddish brown|
|Diacetylmorphine HCl (Heroin)||Deep purplish red|
|Dimethylamylamine (DMAA)||No color change (fizzes)|
|Dimethoxy-meth HCl||Moderate olive|
|Doxepin HCl||Blackish red|
|Dristan||Dark grayish red|
|Methylenedioxyamphetamine HCl (MDA)||Dark Purple - Black|
|Methylenedioxy-N-ethylamphetamine HCl (MDEA)||Dark Purple - Black|
|Methylenedioxymethamphetamine HCl (MDMA)||Dark Purple - Black|
|Methylenedioxypropylamphetamine HCl (MDPR)||Dark Purple - Black|
|Pethidine/Meperidine HCl||Deep brown|
|Mescaline HCl||Strong orange|
|Methadone HCl||Light yellowish pink|
|Methylphenidate HCl||Moderate orange yellow|
|Methylene Blue||Dark Green|
|Modafinil||Yellow/Orange --> Brown|
|Morphine monohydrate||deep purplish red|
|Opium||Dark grayish reddish Brown|
|Oxycodone HCl||Pale violet|
|Propoxyphene HCl||Blackish purple|
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 oxoniumcarbenium salt.
- "Color Test Reagents/Kits for Preliminary Identification of Drugs of Abuse" (PDF). Law Enforcement and Corrections Standards and Testing Program. July 2000. Retrieved 2011-07-24.
- "Marquis Reagent Testing Kit (White Label)". Testing Kits. DanceSafe. Retrieved 2011-07-22.
- "Adulterant Screening Kit Instructions". DanceSafe. Retrieved 2011-07-24.
- Morris, Jeremiah. Color Tests and Analytical Difficulties with Emerging Drugs. Johnson County Sheriff’s Office Criminalistics Laboratory: NIST. p. 36. Retrieved 10 May 2014.
- Morris, Jeremiah (2004). "Analytical Profile of Modafinil" (PDF). Microgram Journal 3 (1-2): 28. Retrieved 2013-10-09.
- Lancashire, Robert J. (2011-10-13). "Unit 9: Crime - Reagent Kits". University of the West Indies, Mona Campus. Retrieved 2014-03-17.
- Shulgin on the Test
- 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)
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