Reagent reference
Reference guide to colorimetric reagent tests and their use
General guidance
- Always test in a well-ventilated area — reagents contain strong acids.
- Use a ceramic or plastic test surface, not metal.
- Use a very small amount of substance (pin-head size).
- Photograph results immediately — colours can change over time.
- A NEGATIVE result (no colour change) does not mean the substance is safe — some compounds do not react with colorimetric reagents.
- Reagent tests are a screening tool only. They cannot confirm purity, potency, or the absence of all possible adulterants.
- For opioids and any pressed pills from illicit sources, always combine colorimetric tests WITH a fentanyl test strip.
- Naloxone should be on hand whenever opioids or opioid-adjacent substances are used.
- GCMS (gas chromatography-mass spectrometry) testing via services such as Energy Control, WEDINOS, or The Loop provides definitive identification where available.
Reagents
Marquis
Composition
Sulfuric acid + formaldehyde
Primary use
Broad indicator for amines — amphetamines (orange/brown), MDMA (purple/black), opioids (purple/black)
Where to buy
Available from DanceSafe, Bunk Police, Reagent Tests UK and others
Mecke
Composition
Sulfuric acid + catechol
Primary use
Opioids (blue/black), MDMA (blue/black), DXM (blue/black), ketamine (yellow/orange)
Where to buy
Available from same sources as Marquis
Mandelin
Composition
Sulfuric acid + ammonium metavanadate
Primary use
Ketamine (orange/red), amphetamines (green/black), opioids (brown/black)
Where to buy
Available from major reagent suppliers
Simon's
Composition
Sodium carbonate + sodium nitroprusside + acetaldehyde
Primary use
Distinguishes secondary amines (MDMA = blue) from primary amines (MDA = no reaction)
Where to buy
Available from major reagent suppliers
Froehde
Composition
Sulfuric acid + molybdic acid
Primary use
Opioids, MDA/MDMA variants, harmala alkaloids
Where to buy
Available from major reagent suppliers
Ehrlich
Composition
DMAB (p-dimethylaminobenzaldehyde) + hydrochloric acid
Primary use
Indoles — LSD, DMT, psilocybin, tryptamines → purple/violet. Critical for blotter testing.
Where to buy
Available from DanceSafe, Bunk Police, Reagent Tests UK
Hofmann
Composition
p-DMAB + sulfuric acid
Primary use
Ergot alkaloids, LSD → blue/purple. More specific than Ehrlich for lysergamides.
Where to buy
Available from major reagent suppliers
Liebermann
Composition
Potassium nitrate + sulfuric acid
Primary use
Cocaine, amphetamines, alkaloids, cannabinoids
Where to buy
Available from major reagent suppliers
Scott
Composition
Cobalt thiocyanate solution
Primary use
Cocaine-specific → blue. Primary field test for cocaine.
Where to buy
Available from major reagent suppliers
Robadope
Composition
p-nitroaniline + sodium nitrite
Primary use
Primary amines (amphetamine) → orange/red
Where to buy
Available from major reagent suppliers
Duquenois-Levine
Composition
Vanillin/acetaldehyde in ethanol + HCl + chloroform
Primary use
Cannabis/THC field test → purple
Where to buy
Available from major reagent suppliers
Fast Blue B
Composition
Azo dye coupling reagent
Primary use
Cannabinoids → orange/brown. Modern preferred cannabis test.
Where to buy
Available from reagent suppliers
Fentanyl Test Strip
Composition
Immunoassay lateral flow (BTNX or equivalent)
Primary use
Detects fentanyl and many analogues at trace levels. Critical for opioids, cocaine, pressed pills.
Where to buy
Available from DanceSafe, BTNX, harm reduction organisations. Free in many areas via local harm reduction programmes.
Suppliers
- DanceSafe (dancesafe.org) — US-based, free fentanyl strips, reagent kits
- Bunk Police (bunkpolice.com) — wide range of reagent kits
- Reagent Tests UK (reagent-tests.uk) — UK-based
- Energy Control (energycontrol.org) — laboratory GCMS testing service, international
- WEDINOS (wedinos.org) — Welsh drug checking service
- The Loop (wearetheloop.org) — UK festival/venue drug checking