Color Tests

Question 1

Marquis (Reagents)

Answer 1

Formaldehyde and conc. sulfuric acid

Question 2

Marquis (Results)

Answer 2

Generally used for opium derivatives and amines.

Orange: Fentanyl (whisps)

Orange-Brown (effervesces): Methamphetamine

Purple: Heroin; Buprenorphine (very slow)

Purple-Black: MDMA/MDAs

Question 3

Cobalt Thiocyanate/Acidified Cobalt Thiocyanate Test (Use, Reagents, Results)

Answer 3

Used for differentiating cocaine HCl and cocaine base.

Reagents:
1) cobalt thiocynate, water, and glycerin
2) Plus conc. HCl

1) Blue for Cocaine HCl, No reaction for cocaine base
2) Blue for both

Question 4

Scott’s Test (Use, Reagents, Interpretation)

Answer 4

Use: Mostly Cocaine

1) Aq. cobalt thiocyanate in glycerin
2) Conc. HCl
3) Chloroform

Cocaine HCl will turn blue at step 1. Cocaine (freebase) will turn blue at 2. For both, blue will transfer into chloroform layer at 3.

Question 5

Duquenois-Levine (Use, Reagent, Results)

Answer 5

Used for cannabinoids, although it will react for any phenol with an aliphatic chain.

1) vanillin, acetaldehyde, ethyl alcohol
2) conc. HCl
3) chloroform

THC will turn purple in both 1 and 2. Purple should transfer to chloroform layer at 3.

High CBD levels may appear more blue.

Question 6

Dille Koppanyi

Answer 6

Used for barbiturates

1) 1% cobalt acetate in MeOH
2) 5% isopropylamine in MeOH

Violet-blue for barbiturates

Question 7

Mecke

Answer 7

Used for opium alkaloids.

Selenious acids + conc. sulfuric acid.

Immediate blue or green is indicative of opiates.

Green: Methamphetamine/Fentanyl
Green-Blue: Morphine
Yellow-Green: Oxycodone

Question 8

Van Urk (aka, Erlich’s or P-DMAB)

Answer 8

Used for ergot alkaloids

p-dimethylaminobenzaldehyde (PDMAB, also a name for the test) in EtOH + conc. HCl

LSD/psilocin/psilocybin: Purple

CBNs: red
yellow: Primary aromatic amines

Question 9

Sodium Nitroprusside

Answer 9

Used for Secondary Amines

Aq. sodium nitroprusside with acetaldehyde
Aq. sodium carbonate

Meth and MDMA - purple to black

Question 10

Ferric Chloride

Answer 10

GHB

Ferric chloride in EtOH + NaOH

GHB = orange-brown

Question 11

Mandelin

Answer 11

Alkaloids

ammonium vanadate + conc. sulfuric

MDA/MDMA = blue to black
blue-green=amphetamine
yellow-methampetamine

Question 12

Chens

Answer 12

Ephedrine and pseudoephedrine

copper sulfate, aq acetic acid, NaOH

violet for positive

Question 13

Weber

Answer 13

psilocin/psilocybin

Fast blue B + conc. HCl

red to blue reaction = +

Question 14

Froehde

Answer 14

Opioids

Molybdic acid + conc. sulfuric

Question 15

Liebermann’s

Answer 15

alkaloids

sodium or potassium nitrite + conc sulfuric