Marquis vs Mecke vs Froehde: Which Reagent Should You Buy First?
Disclosure: we may earn a commission when you buy through links on this page, at no extra cost to you. Our picks are based on the testing protocols used by harm reduction services — never on commission rates.
Top Picks at a Glance
| Award | Product | Price | |
|---|---|---|---|
| Buy First | Marquis Reagent Test Kit (MDMA & Stimulants) | $20.00 | Check Price |
| Buy Second | Mecke Reagent Test Kit | $20.00 | Check Price |
| Buy Third | Froehde Reagent Test Kit | $20.00 | Check Price |
| Skip the Choice | Essential Drug Test Kit (3-in-1) | $55.00 | Check Price |
Three Bottles, Three Jobs
Marquis, Mecke and Froehde get grouped together because they are the three reagents most often used on the same samples — but they are not interchangeable. Each has a chemistry that makes it strong on one drug class and blind on another. Understanding the split is the difference between owning reagents and actually using them well.
Head-to-Head
| Marquis | Mecke | Froehde | |
|---|---|---|---|
| Price | $20.00 | $20.00 | $20.00 |
| Core strength | Broadest screen | Opioids | Cathinones |
| MDMA reaction | Purple → black | Blue → green-black | Green-black → blue-black |
| Amphetamine | Orange → brown | No reaction | Weak/none |
| Heroin | Purple-brown | Blue-green | Purple-brown |
| Cathinones | Weak yellow (easy to misread) | Weak | Distinct yellow → green splits |
| 2C-B | Yellow-green | Brown-green | Green-blue |
| Blind spot | MDMA vs MDA; subtle cathinones | Amphetamines | Amphetamines |
Marquis: The Default First Bottle — $20.00
Marquis (formaldehyde + sulfuric acid) reacts visibly with more drug classes than any other single reagent — which is why nearly every harm reduction service worldwide runs it first.
Pros: widest coverage per drop; fast, dramatic color shifts that are easy to read; the reference reagent for nearly every published color chart.
Cons: cannot separate MDMA from MDA; cathinone reactions are weak and easy to misread as a pass; tells you nothing about ketamine or LSD.
Mecke: The Opioid Lens — $20.00
Mecke (selenious acid based) shines where Marquis blurs: opioids. Heroin, oxycodone and morphine each produce more distinct color paths under Mecke, and its blue-to-green MDxx reaction is a strong second confirmation for pressed pills.
Pros: best mainstream reagent for opioid differentiation; clean MDxx cross-check; complements Marquis with zero overlap in blind spots on opioids.
Cons: near-silent on amphetamines; still cannot split MDMA/MDA; not a cathinone specialist.
Froehde: The Cathinone Detector — $20.00
Froehde (molybdic acid based) exists for the modern problem: synthetic cathinones sold as MDMA. Where Marquis gives an ambiguous darkening, Froehde produces distinct yellows and greens that make substitution obvious. It also usefully distinguishes MDMA from MDA — something neither of the other two can do.
Pros: the best mainstream reagent against bath-salt substitution; MDMA/MDA differentiation; strong synthetic opioid reactivity.
Cons: weak on amphetamines; less published third-party color data than Marquis; works best as a *confirming* reagent rather than a first screen.
The Right Buying Order
- [Marquis](/kits/marquis-reagent) — maximum information from bottle one
- [Mecke](/kits/mecke-reagent) — adds the opioid lens and MDxx confirmation
- [Froehde](/kits/froehde-test-kit) — closes the cathinone gap
Or skip the sequencing entirely: the Essential 3-in-1 swaps Mecke/Froehde for Morris and Ehrlich (adding ketamine and LSD coverage instead), and the 6-in-1 Pro simply includes everything. If your use case is specifically MDMA, the MDMA Complete Kit with Marquis + Simon's + Froehde is the tighter buy — full reasoning in our MDMA guide.
Whichever you choose, read results against the reaction color chart under white light, on a white surface, within the first 30-60 seconds. Color drift after several minutes means nothing.
Frequently Asked Questions
Can I use two reagents on the same sample spot?
No — each reagent needs a fresh, separate sample. Mixing reagents (or dropping onto an already-reacted spot) produces meaningless colors. Use a multi-well ceramic tray and 2-5 mg per well.
Why did my reaction not match the chart exactly?
Cuts and binders shift colors, lighting changes perception, and mixtures react as mixtures. The rule is conservative: if the reaction is not clearly the expected one, treat the sample as unidentified.
Which reagent is best for pressed ecstasy pills?
Run all three if you can — that is the point of the trio. If you own only one, Marquis catches the most dangerous total-substitution cases; Froehde is the strongest single upgrade after it for pills specifically.
Do these reagents expire?
Yes — roughly 1-2 years stored cool and dark. Marquis shows its age by darkening toward brown in the bottle; test a known-clean surface drop if unsure, and replace any bottle whose neat color has visibly changed.
Keep Reading
Last updated 2026-07-17. Prices verified against TestKitPlus at time of update and may change. Testing reduces risk — it never eliminates it.