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DRUG ANALYSIS
CLASS NOTES
FORENSIC DRUG ANALYSIS
 Forensic drug analysis is the chemical testing of foreign
substances.
ROLE OF THE FORENSIC CHEMIST /
DRUG ANALYST
 Forensic Chemist / Drug Analyst Determine:
 1) The chemical properties of the substance.
 2) The identity of the substance.
 3) Determine if the substance is an illicit drug.
 4) Record the amount of substance.
 5) Prepare and provide expert testimony in court.
 6) Determine the proper analytical procedures to identify the drug.
SCREENING AND CONFIRMATION
 The first step of an analyst must be to reduce the possible
drug type the substance can be to a small manageable
number.
 This is called a screening test.
 Typically a color test is performed to help narrow down the
possibilities.
SCREENING AND CONFIRMATION
 The second step of a analyst is to confirm the substances
identity.
 Forensic analyst normally rely on several tests for a routine
drug identification scheme.
COMMON DRUG IDENTIFICATION
TESTS
 The most common drug identification tests include:
 1) Color Tests
 2) Microcrystalline Tests
 3) Chromatography
 4) Spectrophotometry
 5) Mass Spectrometry
COLOR TESTS
 Many drugs yield characteristic colors when brought into
contact with specific chemical reagents.
 Color tests are used for screening purposes only and are
never taken as conclusive identification of unknown drugs.
TYPES OF COLOR TESTS
 Marquis Test – turns purple in the presence of heroin and
morphine. It also turns orange – brown when mixed with
amphetamines and methamphetamines.
 Dillie – Koppanyi Test – turns violet – blue in the presence of
barbiturates.
TYPES OF COLOR TESTS
 Duquenois – Levine Test – turns purple when marijuana is
mixed with chloroform.
 Van Urk Test – turns blue – purple in the presence of LSD.
 Scott Test – turns blue in the presence of cocaine; even
further if you add hydrochloric acid it transforms to a clear
pink color.
MICROCRYSTALLINE TESTS
 A microcrystalline test is considered more specific than a
color test.
 In this test a drop of chemical reagent is added to a small
quantity of the drug on a microscope slide.
 After a short time, a chemical reaction ensues, producing a
crystalline precipitate.
MICROCRYSTALLINE TEST
CHROMATOGRAPHY
 Chromatography is a means of separating and tentatively
identifying the components of a mixture.
 The Theory of Chromatography known as Henry’s Law states
that at a constant temperature, the amount of gas that
dissolves in a liquid is directly proportional to the partial
pressure of that gas in equilibrium with that liquid.
CHROMATOGRAPHY
 Example of Henry’s Law:
 If a beaker of water is covered by a bell jar, the gas molecules
escape into the enclosed air. The molecules that remain are
in liquid phase, the escaped molecules are in gas phase.
 Forensic analyst use chromatography to allow the separate
gas molecules for each chemical component to escape at
their own rate leaving behind a trail of molecules on the
chromatograph.
TWO MAIN TYPES OF
CHROMATOGRAPHY
 1) TLC – Thin Layer Chromatography
 2) Gas Chromatography
THIN LAYER CHROMATOGRAPHY
 TLC uses a solid stationary phase, usually coated onto a glass
plate, and a mobile liquid phase to separate the components
of the mixture.
GAS CHROMATOGRAPHY
 Gas Chromatography separates mixtures on the basis of their
distribution between a stationary liquid phase and a mobile
gas phase.
SPECTROPHOTOMETRY
 Spectrophotometry is the study of the absorption of light by
chemical substances.
 Beer’s Law states that absorption of a material sample is
directly proportional to its thickness (path length).
 Most forensic laboratories use ultraviolet (UV) and infrared
(IR) spectrophotometers to characterize chemical
compounds.
UV SPECTROPHOTOMETRY
 UV spectrophotometry measures absorbance of UV and
visible light as a function of wavelength and frequency.
 This technique does not provide a definitive result because
other drugs or materials have similar absorption to heroin.
IR SPECTROPHOTOMETRY
 Infrared Spectrophotometry provides a far more complex
pattern than UV spectrophotometry.
 It identifies different materials that have distinctively
different infrared spectra, each IR spectrum is equivalent to a
“fingerprint” of that substance.
MASS SPECTROPHOTOMETRY
 Mass Spectrophotometry characterizes organic molecules by
observing their fragmentation pattern after their collision
with a beam of high energy electrons.