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Forensic Drug
Analysis
Chapter 5 Drugs
Screening and Confirmation
Forensic Scientists determine the identity of
drugs using…
 Screening Tests – preliminary tests used
to reduce the # of possible identities of an
unknown substance (color tests &
microcrystalline tests)
 Confirmation – a single test that
specifically identifies a substance.
Qualitative vs. Quantitative
Identification of drugs may be…
 Qualitative – descriptive (An unknown
sample may be determined to contain
heroin and quinine.)
 Quantitative-amount (A sample may be
determined to contain 10 % heroin and
90% quinine)
Color Tests
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When mixed with a
certain reagent, a drug
can produce a
characteristic color
Useful for field
investigators
Screening tests only
YouTube - Spray drug test
kit for Cocaine residue
detection
Heroin
Meth
Color Tests
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Marquis – heroin, morphine, opium
derivatives, amphetamines
Dille-Koppanyi-barbiturates
Duquenois-Levine – marijuana
Van Urk – LSD
Scott test - cocaine
Microcrystalline Tests

A test that identifies a
specific substance
based on the color
and shape of crystals
formed when the
substance is mixed
with specific reagents.
Methamphetamine
Chromatography

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An analytical technique
used to separate the
components of a
mixture for the purpose
of identification and
quantification.
Useful to forensic
scientists because drugs
often come in the form
of a mixtures
Chromatography
All types of chromatography include:
 Stationary Phase – a solid substance used to
adsorb components of a mixture.
 Mobile Phase – a liquid or gas that flows through
the stationary phase.
 Components of a mixture are separated based
on the speed that they move through the
stationary phase.
 The speed of a substance depends on how
strongly it is attracted to the mobile and
stationary phases.
Thin-Layer Chromatography
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TLC uses a solid
(silica gel or
aluminum oxide)
coated on a plastic or
glass plate.
The plate is immersed
in a liquid solvent
YouTube - Thin Layer
Chromatography of
Felt Tipped Pens
Thin Layer Chromatography
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As the solvent travels
up the
chromatogram,
components of a
mixture travel at
different speeds.
Unknown substances
can be compared to
reference samples.
Gas Chromatography
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GC – solid stationary
phase/gaseous mobile
phase
Complex mixtures can
easily be analyzed
Quantitative results can
be obtained
http://www.shsu.edu/~ch
m_tgc/sounds/flashfiles/G
C.swf
Spectrophotometry
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UV, Visible, and Infrared Light can be used
to analyze unknown substances
Substances absorb, reflect, or transmit
various wavelengths of light.
This property can be used to indentify or
quantify unknown substances.
UV-Visible Spectrophotometry
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The absorption of UV or visible light can
be used to indentify or quantify an
unknown substance
Identification is not exact; other
substances can have similar absorption
spectra
http://wps.prenhall.com/wps/media/object
s/3801/3892550/DB.swf
UV-Visible Spectrophotometry
Infrared Spectrophotometry

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Unknown substances can be analyzed by
measuring the absorption of infrared light.
The absorption pattern is much more
complex than UV.
Substances can be specifically identified
by their IR spectrum (like a fingerprint)
Infrared Spectrophotometry
Mass Spectrometry
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Often used as a detector for Gas
Chromatography
A substance is bombarded with highenergy electrons
This causes the substance to ionize.
The ions break up into smaller fragments.
The fragments are separated by mass
The fragmentation pattern is unique to
each individual substance
Mass Spectroscopy