How to Read a Marquis Reagent Test Result
What each Marquis reagent color means: MDMA turns purple to black, meth and amphetamine turn orange. A full color chart and how to avoid misreads.
June 10, 2026 · Jordan Mercer
Contents
Marquis tells you which chemical class your sample belongs to, by the color it turns in the first 30 to 60 seconds. MDMA goes purple to black. Amphetamine and methamphetamine go orange to brown. Most other substances give their own signature color, or nothing at all.
It is the best first reagent because it reacts with the phenethylamines that make up most ecstasy and amphetamine samples. It also cannot tell MDMA from MDA, cannot see fentanyl, and cannot measure dose. Here is the chart, then the mistakes that cause misreads.
The color chart
Marquis starts clear to yellow. Read it in the first 30 to 60 seconds, because every reagent eventually darkens on its own and a slow drift to brown after several minutes is not a result.
| Substance | Marquis color |
|---|---|
| MDMA | Purple → black |
| MDA | Purple → black (looks the same as MDMA) |
| Amphetamine | Orange → brown |
| Methamphetamine | Orange → brown |
| DXM (dextromethorphan) | Gray → black, often slow |
| 2C-B and many 2C-x | Yellow → green |
| Opioids (heroin, morphine) | Purple (different shade, context matters) |
| Ketamine | No reaction (stays yellow) |
| Cocaine | No reaction (stays yellow) |
| Sugars / inert fillers | No reaction, or slow brown |
Three signals carry most of the weight. Purple to black means a phenethylamine is present. Orange means amphetamine-type. Staying yellow means Marquis is the wrong reagent for whatever you have, not that the sample is clean.
Why those colors happen
Marquis is formaldehyde and concentrated sulfuric acid. The acid drives a reaction with the target molecule that produces a colored compound, and the structure of the molecule decides the color. The methylenedioxy ring shared by MDMA and MDA produces the deep purple-to-black product. The plainer amphetamine backbone produces the orange-brown one. Molecules with nothing for Marquis to grab, like ketamine and cocaine, give you nothing.
Which is exactly why Marquis cannot separate molecules that share the key feature. MDMA and MDA both carry the methylenedioxy ring, so both go purple to black and Marquis cannot tell them apart. That matters, because MDA is longer and harder on the body. Separating them takes a second reagent.
Running it
- Use a tiny sample. Scrape about 10 mg, roughly a match head, onto a white ceramic plate or the kit tray. More sample does not give a better result, it wastes reagent and makes the color harder to read.
- Add one or two drops directly onto the sample. Never touch the dropper to the sample; that contaminates the whole bottle.
- Watch the first minute. Note the color at 5, 15, 30 and 60 seconds. Speed and peak color are both information.
- Read it under white light against the kit’s printed chart. Phone screens and colored lighting distort what you see.
- Photograph it if you want a record, then rinse the plate with water before the next reagent.
Five ways people misread this test
- Reading too late. Every reagent darkens toward brown or black over several minutes no matter what it touched. A reaction that only goes dark at two or three minutes is not an MDMA result. Judge the first minute.
- Too much sample. A heavy pile looks uniformly black and hides the real hue.
- Bad light. Dim or colored lighting is the most common reason people call orange purple. Use daylight or a white LED.
- Treating one reagent as the whole answer. Marquis confirms a class, not an identity, and presumptive color tests carry a documented rate of ambiguous and misread results in laboratory evaluation. One reagent is a starting point, not a verdict.
- Assuming purple means safe. A purple-to-black result is consistent with MDMA. It says nothing about dose, nothing about minor adulterants, and nothing about fentanyl.
What to run alongside it
- Simon’s separates MDMA from MDA: blue for MDMA, no color for MDA. This is the one thing Marquis cannot resolve, and it is why the distinction is worth a second bottle. See MDA vs MDMA.
- Mecke adds a second confirmation, turning blue-green to black for MDMA, and helps flag some cathinones.
- A fentanyl test strip, every time. No reagent detects fentanyl, and fentanyl in stimulants is a leading cause of overdose death. Dissolve the sample in 1 teaspoon (5 mL) of water per 10 mg, or 2 teaspoons (10 mL) for MDMA and methamphetamine, to avoid false positives, then dip. Read it the right way round: one line is positive, two lines is negative. Strips are single use, one per sample. Full method in our fentanyl test strip guide.
Marquis plus Simon’s plus a strip is the practical at-home standard, and it is what the multi-reagent kits are built around. You can buy Marquis on its own if that is all you need.
For the full walkthrough on testing ecstasy, see how to test your MDMA. For dosing and safer use, our MDMA harm reduction guide.