Marquis reagent
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 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.
It was first discovered in 1896 and described by the Russian pharmacologist, Eduard Marquis in his magister dissertation in 1896; and named after him, and was tested for the first time at the University of Dorpat. The reagent should be stored in the freezer for maximum shelf life
It is the primary presumptive test used in Ecstasy testing kits. It can also be used to test for such substances as opiates, and phenethylamines.
The test is performed by scraping off a small amount of the substance and adding a drop of the reagent. 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.| Substance | Color | Time | 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 |
| Substance | Color |
| βk-2C-B | Bright orange |
| 2C-B | Green-Yellow |
| 2C-I | Green-Yellow |
| 2,5-Dimethoxy-4-bromoamphetamine | Olive Green - Yellow |
| 2-FMA | Rapidly fizzes and dissolves. Colourless/Light yellow |
| 25I-NBOMe | Orange |
| 25C-NBOMe | Clear |
| 25B-NBOMe | Dark Green |
| 4F-MPH | 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 HCl | Deep reddish brown |
| Benzylpiperazine | Clear |
| Buprenorphine HCL | Pinkish violet |
| Butylone | Yellow |
| Chlorpromazine HCl | Deep purplish red |
| Codeine | Very dark purple |
| Caffeine | Clear |
| Cocaine | Clear |
| d-Amphetamine HCl | Strong reddish orange - Dark reddish brown |
| d-Methamphetamine HCl | Deep reddish orange - Dark reddish brown |
| Diacetylmorphine HCl | Deep purplish red |
| Dimethylamylamine | No color change |
| Dimethyltryptamine | Orange |
| Dimethoxymethamphetamine HCL | Moderate olive |
| Doxepin HCl | Blackish red |
| Dristan | Dark grayish red |
| Exedrine | Dark red |
| LSD | Olive black |
| Methoxetamine | Slow pink |
| 3,4-Methylenedioxyamphetamine HCl | Dark Purple - Black |
| Methylenedioxy-N-ethylamphetamine HCl | Dark Purple - Black |
| Methylenedioxymethamphetamine HCl | Dark Purple - Black |
| Methylenedioxypropylamphetamine HCl | Dark Purple - Black |
| Methylone | Yellow |
| Methylenedioxypyrovalerone | Yellow |
| 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 |
| Sugar | Dark brown |