Forensic labs are often called in to identify unknown powders, liquids and pills that may be illicit drugs. There are basically two categories of forensic tests used to analyze drugs and other unknown substances: Presumptive tests (such as color tests) give only an indication of which type of substance is present -- but they can't specifically identify the substance. Confirmatory tests (such as gas chromatography/mass spectrometry) are more specific and can determine the precise identity of the substance.
Australian Federal Police via Getty Images Forensic technicians are often calledto identify unknown drugs. A beauty student allegedly tried to smuggle more than10,000 amphetamine tablets into Australia.
Color tests expose an unknown drug to a chemical or mixture of chemicals. What color the test substance turns can help determine the type of drug that's present. Here are a few examples of color tests:
Type of Test Chemicals
Formaldehyde and
Marquis Color
concentrated sulfuric acid
Cobalt thiocyanate, distilled
Cobalt thiocyanate
water, glycerin, hydrochloric acid, chloroform
Cobalt acetate and
Dillie-Koppanyi
isopropylamine
P-dimethylaminobenzaldehyde,
VanUrk
hydrochloric acid, ethyl alcohol
Duquenois-Levine Test Vanillin, acetaldehyde, ethyl alcohol, chloroform
Other drug tests include ultraviolet spectrophotometry, which analyzes the way the substance reacts to ultraviolet (UV) and infrared (IR) light. A spectrophotometry machine emits UV and IR rays, and then measures how the sample reflects or absorbs these rays to give a general idea of what type of substance is
