How Reagent Reactions Work.
Reagent testing is colorimetric chemistry — each reagent contains chemicals that react with specific molecular structures to produce characteristic color changes. Understanding these reactions helps you interpret results correctly and avoid dangerous misidentification.
Colorimetric Chemistry
Reagent testing works on a simple principle: specific chemical structures react with specific reagents to produce colored products. By observing the color, speed, and intensity of the reaction, you can identify what's in your sample.
Functional Group Detection
Each reagent targets a specific molecular feature. Marquis detects the methylenedioxy ring. Ehrlich detects the indole structure. Simon's distinguishes primary from secondary amines. By running multiple reagents, you build a chemical fingerprint of the substance.
Reaction Speed Matters
The speed of color development is diagnostically important. MDMA with Marquis turns purple-black instantly. LSD with Ehrlich develops over 1–5 minutes. PMA with Marquis only shows color after a delay. Watch the clock and the color.
Multiple Reagents Required
A single reagent is never enough. Many substances produce similar colors. MDMA and DXM both turn black with Marquis — but Mecke tells them apart instantly (green vs brown). The three-reagent minimum is not optional.
Sample Size Precision
Too much sample causes the "hook effect" — color saturation that masks the true reaction. Too little produces false negatives. Use 2–5mg — about the size of a grain of salt. A 10mg micro scoop ensures consistency.
Reagent Reaction Chart
Every major reagent, its target substances, expected colors, and diagnostic notes. Use this as a field reference or study guide. For confident identification, always run at least three reagents.
The most versatile single reagent. Formaldehyde in sulfuric acid reacts with the methylenedioxy ring structure in MDxx compounds to produce a deep purple/black color. Also distinguishes amphetamine (orange) from methamphetamine (red-brown). Every testing kit should start here.
Pro tip: Always test first with Marquis. If the instant purple/black appears, you've confirmed MDxx. If it's orange without any purple, you're looking at amphetamine or PMA — do not assume MDMA.
| Substance | Expected Color |
|---|---|
| MDMA / MDA / MDEA | Purple to Black |
| Amphetamine | Orange / Brown |
| Methamphetamine | Orange / Red-Brown |
| 2C-B / 2C-I | Yellow to Green |
| DMT | Orange / Brown |
| PMA / PMMA | No color change → Orange/Brown (slow) |
| Aspirin | Pink → Deep Red (slow) |
| Caffeine | No reaction |
p-DMAB (para-dimethylaminobenzaldehyde) specifically reacts with the indole ring structure found in LSD, DMT, psilocybin, and other tryptamines. Produces a pink-to-purple color when indoles are present. The most essential test for any psychedelic.
Pro tip: Ehrlich does NOT react with NBOMe compounds. If a tab sold as LSD produces no color change with Ehrlich, it is NOT LSD. Always confirm with a second reagent like Hofmann.
| Substance | Expected Color |
|---|---|
| LSD | Pink → Purple (develops 1–5 min) |
| DMT | Purple |
| Psilocybin / Psilocin | Purple |
| 5-MeO-DMT | Purple |
| NBOMe compounds | No reaction |
| Melatonin | Pink → Purple (false positive) |
Selenious acid in sulfuric acid produces distinctive green-to-blue color shifts with MDMA, heroin, and morphine. Excellent secondary confirmation reagent and critical for opioid identification. Its green reaction with MDMA is unmistakably different from Marquis's purple.
Pro tip: Mecke is your go-to for differentiating heroin from fentanyl. Heroin turns green; fentanyl produces different (often no) reaction. Use in combination with Marquis for confident MDMA confirmation.
| Substance | Expected Color |
|---|---|
| MDMA | Green → Dark Blue / Black |
| Heroin | Green → Blue-Green |
| Morphine | Blue-Green |
| Codeine | Blue-Green |
| Oxycodone | Green → Dark Green |
| DXM | Brown / Dark Brown |
Cobalt thiocyanate is purpose-built for ketamine detection. The cobalt ion forms a coordination complex with ketamine that produces an unmistakable deep purple/blue color. Also reacts with cocaine, so use a secondary reagent to confirm.
Pro tip: Morris is the gold standard for ketamine testing. The reaction is instant and dramatic. If Morris produces no reaction on a sample sold as ketamine, it is not ketamine — likely an RC dissociative.
| Substance | Expected Color |
|---|---|
| Ketamine | Deep Purple / Blue (instant) |
| 2F-DCK | Purple / Blue |
| DCK | Purple / Blue |
| Cocaine | Blue (different shade) |
| PCP Analogues | No reaction or weak |
A two-part reagent (sodium nitroprusside + acetaldehyde + sodium carbonate) that reacts exclusively with secondary amines — not primary amines. This is the ONLY reagent that reliably tells MDMA (secondary amine) from MDA (primary amine).
Pro tip: Simon's is useless without Marquis first. Marquis confirms MDxx; Simon's tells you if it's MDMA or MDA specifically. If Marquis goes purple but Simon's stays clear, you have MDA — which is more neurotoxic and requires adjusted dosing.
| Substance | Expected Color |
|---|---|
| MDMA (secondary amine) | Bright Blue |
| Methamphetamine | Bright Blue |
| MDA (primary amine) | No reaction |
| Amphetamine | No reaction |
| PMK (MDMA precursor) | No reaction |
Molybdic acid in sulfuric acid excels at detecting synthetic cathinones (bath salts) that Marquis alone might misidentify. With MDMA it produces a greenish-black color; with cathinones, yellow/orange to brown. The third point in the MDMA verification triangle.
Pro tip: Froehde is the cathinone sniffer. If Marquis and Simon's look like MDMA but Froehde gives an unexpected color, you likely have a cathinone mixture. Always use Froehde as your third-point MDMA confirmation.
| Substance | Expected Color |
|---|---|
| MDMA | Greenish-Black → Blue-Black |
| Synthetic Cathinones | Yellow / Orange → Brown |
| Aspirin | Deep Purple / Blue |
| LSD | Yellow / Green |
Potassium nitrite in sulfuric acid is the broadest-spectrum general screening reagent. Produces distinct colors with cocaine (yellow/amber), MDMA (black), levamisole (olive green), ketamine (pale yellow), and sugar alcohols (no reaction).
Pro tip: Liebermann is your first-line cocaine test. Pure cocaine = yellow/amber. If you see olive green, levamisole is present. Use the Cocaine Cuts Kit for comprehensive adulterant screening.
| Substance | Expected Color |
|---|---|
| Cocaine | Yellow / Amber |
| MDMA | Black / Dark Purple |
| Levamisole | Olive Green |
| Ketamine | Yellow / Pale Yellow |
| Sugar / Mannitol | No reaction |
Ammonium vanadate produces distinctive orange/red colors with ketamine and cocaine. Also effective at detecting PMA/PMMA (green to dark brown). Used as secondary confirmation, especially alongside Morris for ketamine.
Pro tip: Use Mandelin as secondary confirmation after Morris for ketamine. If both produce the expected colors, you have high confidence. Mandelin's PMA detection makes it valuable in any comprehensive stimulant screening.
| Substance | Expected Color |
|---|---|
| Ketamine | Deep Orange / Red |
| Cocaine | Orange / Yellow |
| PMA / PMMA | Green → Dark Brown |
A modified Ehrlich reagent (p-DMAB in methanol rather than HCl) that reacts more slowly but more specifically with LSD and lysergamides. The slow purple/blue development (5–30 minutes) is actually a feature — it rules out false positives from melatonin or other fast-reacting indoles.
Pro tip: Hofmann is a confirming reaction for LSD. If Ehrlich turns purple quickly but Hofmann takes 15+ minutes, you likely have LSD. If both react instantly, consider melatonin contamination. Hofmann patience = accuracy.
| Substance | Expected Color |
|---|---|
| LSD | Blue / Purple (develops 5–30 min) |
| Psilocybin | Blue / Purple |
Specifically designed to detect primary amines — the chemical class that includes 2C-B, 2C-I, amphetamine, and MDA. Produces a pink-to-purple color with primary amines while leaving secondary amines (MDMA, methamphetamine) unreactive.
Pro tip: Robadope is the primary 2C-B test. If Marquis goes yellow-green AND Robadope goes pink-purple, you have a 2C-x compound. Robadope's specificity for primary amines makes it the counterpart to Simon's (which reacts with secondary amines).
| Substance | Expected Color |
|---|---|
| 2C-B | Pink → Purple (primary amine) |
| 2C-I / 2C-E | Pink → Purple |
| MDMA (secondary amine) | No reaction |
Phosphotungstic acid reagent specifically formulated to detect piperazine-class compounds (BZP, TFMPP, mCPP) that are often sold as MDMA or amphetamine substitutes. Produces orange-red to dark brown colors with piperazines.
Pro tip: Folin is niche but critical. Piperazines are common MDMA substitutes that standard reagents may not flag. If Marquis turns orange-brown (like amphetamine), run Folin — a positive Folin reaction means piperazines, not amphetamine.
| Substance | Expected Color |
|---|---|
| BZP | Orange / Red |
| TFMPP | Dark Brown |
| mCPP | Red-Brown |
Ready to Start Testing?
Every kit on our catalog ships with a full-color reaction chart, testing instructions, and the reagents you need for confident presumptive identification. Start with the 3-in-1 starter kit or build your own from individual reagents.
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