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What is Forensic Chemistry
• Applied analytical chemistry
• Qualitative analysis
– Identify material – what is it
– Must be done before quantitative
Forensic Chemistry
• Quantitative analysis
– Percentage of components in a mixture
• Comparative analysis
– Identification
– Classification
– individualization
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Areas of Forensic Chemistry
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• Technique where mixtures are separated into
components by attraction to a stationary phase while
being propelled by a moving phase
– Thin layer (TLC)
– Gas liquid (GLC or GC)
– High pressure liquid (HPLC)
– Arson/explosives/ GSR
– Inks/paints/dyes
– Fibers/ paper/plastic/ adhesives
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• Used to identify
– Inks
– Drugs
– Accelerants
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Microscopy
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Drug Analysis
Fibers/hair
Soil
Glass
Drug crystals
Inks
Paints
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Chromatography
Chromotography
Microscopy
Drug analysis/Toxicology
Chemical analysis of physical evidence
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Presumptive tests
Color tests
Crystal tests using microscopy
TLC
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Introduction
• A drug can be defined as a natural or synthetic
substance that is used to produce physiological or
psychological effects in humans or other higher order
animals.
• Narcotic drugs are analgesics, meaning they relieve
pain by a depressing action on the central nervous
system. This effects functions such as blood pressure,
pulse rate, and breathing rate.
• The regular use of a narcotic drug will invariably lead
to physical dependence.
• The most common source for these narcotic drugs is
opium, extracted from poppies.
Chapter 9
DRUGS
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• Government maintains 5 schedules of
classifications for controlled substances
• Based on
• Inappropriate use
• Unwarranted use
• Over use
• May or may not be
addictive
– Potential for abuse
– Potential for dependence
– Medical value
• US Attorney General has authority to add,
delete, or reschedule a drug as more info
becomes available
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Dependence
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Schedule I
• Physical dependence occurs when
the drug becomes necessary for
their body to function normally
• Psychological dependence occurs
when a person thinks they need a
drug to function normally
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Abuse
Controlled Substances Act
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• High potential for abuse
• No currently accepted medical use
• Lacks accepted safety of use in
treatment under medical supervision
Heroin
Marijuana
PCP
LSD
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Schedule III
Schedule II
• High potential for abuse
• Has an accepted medical use or a medical
use w/severe restrictions
• Potential for severe psychological/physical
dependence
Cocaine
opium
methodone
PCP
Dronabinol
Most amphetamine & barbiturate derivatives
synthetic marijuana
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• Less potential for abuse than I & II
• Current accepted medical use in US
• low/moderate physical dependence or high
psychological dependence
Anabolic steroids
all barbiturate preparations (except
phenobarbitol) not covered in II
Certain codeine preparations
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Schedule IV
• Low abuse potential
• Valid medical use in US
• Lower potential for producing dependence than
schedule IV
Robitussin
Low dose codeine preps.
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lethargy or sluggishness
Narcotics
Hallucinogens
Depressants
stimulants
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Narcotics-induce a state of
Types of Drugs
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Schedule V
– Lower potential for abuse than schedule III
– Valid medical use in US
– Abuse may lead to limited dependence
relative to III
Darvon
Phenobarbital
Valium
Librium
tranquilizers
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• Narcotics a analgesics –relieve pain
• Most come from the poppy plant
• Example Narcotics
Morphine
Methadone
Heroin
Codeine
OxyContin
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Opiates
Other Opiates
• Type of narcotic
• Morphine is readily extracted from opium and is
used to synthesize heroin.
• Addicts frequently dissolve heroin in water by
heating it in a spoon, and then inject in the skin.
• Heroin produces a “high” that is accompanied by
drowsiness and a sense of well-being that
generally last for three to four hours.
• Codeine is also present in opium, but it is usually
prepared synthetically from morphine.
• OxyContin, with the active ingredient oxycodone,
is not derived from opium or morphine, but does
have the same physiological effects on the body
as do opium narcotics.
• OxyContin is prescribed to a million patients for
treatment of chronic pain.
• Methadone is another well-known synthetic
opiate.
• Methadone which is pharmacologically related to
heroin, appears to eliminate the addict’s desire
for heroin while producing minimal side effects.
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Hallucinogens
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Marijuana
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Other Hallucinogens
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Depressants
• Depressants are another class of drugs.
• Depressants are substances used to
depress the functions of the central
nervous system.
• Depressants calm irritability and anxiety
and may induce sleep.
• These include alcohol (ethanol),
barbiturates, tranquilizers, and various
substances that can be sniffed, such as
airplane glue, model cement, or aerosol gas
propellants such as freon.
• Other hallucinogens include LSD, mescaline, PCP,
psilocybin, and MDMA (Ecstasy).
• LSD is synthesized from lysergic acid, and can cause
hallucinations that can last for 12 hours.
• Phencyclidine, or PCP, is often synthesized in clandestine
laboratories and is often smoked, ingested, or sniffed.
• Phencyclidine is often mixed with other drugs, such as
LSD, or amphetamine, and is sold as a powder (“angle
dust”), capsule, or tablet.
• Oral intake of PCP first leads to feelings of strength and
invulnerability, which may turn to depression, tendencies
toward violence, and suicide.
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• Marijuana is the most controversial drug in this class
because its long-term effects on health are still largely
unknown.
• Marijuana refers to a preparation derived from the plant
Cannabis.
• The chemical substance largely responsible for the
hallucinogenic properties of marijuana is known as
tetrahydrocannabinol, or THC.
• The THC content of Cannabis varies in different parts of
the plant, generally decreasing in the following
sequence: resin, flowers, leaves, with little THC in the
stem, roots, or seeds.
• The THC-rich resin is known as hashish.
• Marijuana does not cause physical dependency, but the
risk of harm is in heavy, long-term use.
• Another class of drugs is hallucinogens;
marijuana is the most well-known member of
this class.
• Hallucinogens cause marked changes in
normal thought processes, perceptions, and
moods.
• Marijuana is the most controversial drug in
this class because its long-term effects on
health are still largely unknown.
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Depressants
Stimulants
• Alcohol (ethyl alcohol) enters the body’s
bloodstream and quickly travels to the brain, where
it acts to suppress the brain’s control of thought
processes and muscle coordination.
• Barbiturates, or “downers,” are normally taken
orally and create a feeling of well-being, relax the
body, and produce sleep.
• Tranquilizers, unlike barbiturates, produce a relaxing
tranquility without impairment of high-thinking
faculties or inducing sleep.
• Sniffing has immediate effects such as exhilaration,
but impairs judgment and may cause liver, heart,
and brain damage or even death.
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• Stimulate (speed up) action in central
nervous system
• The drug classification of stimulants includes
amphetamines, sometimes known as
“uppers” or “speed,” and cocaine, which in
its free-base form is known as crack.
• Stimulants are substances taken to increase
alertness or activity, followed by a decrease
in fatigue and a loss of appetite.
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Stimulants
Club Drugs
• Amphetamine and methamphetamine, often
injected intravenously, cause an initial “rush,”
followed by an intense feeling of pleasure.
• This is followed by a period of exhaustion and a
prolonged period of depression.
• Cocaine, extracted from the leaves of Erythroxylin
coca, causes increased alertness and vigor,
accompanied by the suppression of hunger,
fatigue, and boredom.
• Crack is cocaine mixed with baking soda and
water, then heated.
• Crack is often smoked in glass pipes, and, like
cocaine, stimulates the brain’s pleasure center.
• Crystal Meth
• The term club drugs refers to synthetic drugs that are
used at nightclubs, bars, and raves (all-night dance
parties).
• Substances that are often used as club drugs include,
but are not limited to, MDMA (Ecstasy), GHB (gamma
hydroxybutyrate), Rohypnol (“Roofies”), ketamine,
and methamphetamine.
• GHB and Rohypnol are central nervous system
depressants that are often connected with drugfacilitated sexual assault, rape, and robbery.
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Club Drugs
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Anabolic Steroids
• Methylenedioxymethamphetamine, also known as MDMA or
Ecstasy, is a synthetic mind-altering drug that exhibits many
hallucinogenic and amphetamine-like effects.
• Ecstasy enhances self-awareness and decreases inhibitions;
however, seizures, muscle breakdown, stroke, kidney failure,
and cardiovascular system failure often accompany chronic
abuse.
• Ketamine is primarily used as a veterinary animal anesthetic
that in humans causes euphoria and hallucinations.
• Ketamine can also cause impaired motor functions, high blood
pressure, amnesia, and mild respiratory depression.
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• Yet another category of drugs is the anabolic
steroids.
• These are synthetic compounds that are chemically
related to the male sex hormone testosterone.
• Anabolic steroids are often abused by individuals
who are interested in accelerating muscle growth.
• Side effects include unpredictable effects on mood
and personality, depression, diminished sex drive,
halting bone growth, and liver cancer.
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Drug Identification
Preliminary Analysis
• The challenge or difficulty of forensic drug
identification comes in selecting analytical
procedures that will ensure a specific
identification of a drug.
• This plan, or scheme of analysis, is divided into
two phases.
• Faced with the prospect that the unknown
substance may be any one of a thousand or more
commonly encountered drugs, the analyst must
employ screening tests to reduce these
possibilities to a small and manageable number.
• This objective is often accomplished by subjecting
the material to a series of color tests that will
produce characteristic colors for the more
commonly encountered illicit drugs.
• Microcrystalline tests can also be used to identify
specific drug substances by studying the size and
shape of crystals formed when the drug is mixed
with specific reagents.
– Screening test that is nonspecific and preliminary in
nature to reduce the possibilities to a manageable
number.
– Confirmation test that is a single test that specifically
identifies a substance.
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Color Tests
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• Scott Test
– 3 part test
– Cocaine turns solution A blue
– Blue changes to pink when solution B is added
– Blue reappears in chloroform layer when solution
C is added
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Microcrystalline Tests
Confirmational Determination
• More specific than color tests
• Drop of chemical reagent added to small
quantity of drug on microscope slide
• Chemical reaction occurs producing crystalline
precipitate
• Looking at size & shape of crystals
• Are highly characteristic of the drug
• Once this preliminary analysis is completed, a
confirmational determination is pursued.
• Forensic chemists will employ a specific test to
identify a drug substance to the exclusion of
all other known chemical substances.
• Typically infrared spectrophotometry or mass
spectrometry is used to specifically identify a
drug substance. Sometimes chromatography
can also be used
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Color Tests
• Marquis
– Turns purple in presence of heroin, morphine, &
most opium derivatives
– Orange-brown when mixed w/amphetamines &
metamphetamines
• Dillie-Koppanyl
– Turns violet-blue in presence of bartiturates
• Duquenois-Levine
– Purple top layer is positive test for marijuana
• Van Urk
– Blue-purple in presence of LSD
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Chromatography
Spectrophotometry
• Separates drugs from their dilutants
• Chemist must first have an idea of what the
drug is
• Often performed along with color & crystal
tests
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• Selective absorption of light by drugs in UV or
IR
• UV is not conclusive for a positive ID of a drug
because other materials may very well
produce an indistinguishable spectrum
• IR can specifically identify a substance
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Mass Spectrometry
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• The field investigator has the responsibility of ensuring
that the evidence is properly packaged and labeled for
the laboratory.
• Generally common sense is the best guide, keeping in
mind that the package must prevent the loss of the
contents and/or cross-contamination.
• Often the original container in which the drug was
seized will suffice.
• Specimens suspected of containing volatile solvents
(glue-sniffing) must be packaged in airtight containers
to prevent evaporation of solvent
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• All packages must be marked with
information that is sufficient to ensure
identification by the officer in the future and
establish the chain of custody.
• Any field test results should be forwarded to
lab
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Collection and Preservation
• Readily separates a drug from other
substances that may be present in the drug
preparation
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Chapter 10
FORENSIC TOXICOLOGY
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Introduction
• Toxicologists are charged with the responsibility
for detecting and identifying the presence of
drugs and poisons in body fluids, tissues, and
organs.
• Toxicologists not only work in crime laboratories
and medical examiners’ offices, but may also
reach into hospital laboratories and health
facilities to identify a drug overdose or monitor
the intake of drugs.
• A major branch of forensic toxicology deals with
the measurement of alcohol in the body for
matters that pertain to violations of criminal law.
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Some Bodily
Evidence of Drug Use
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Repeated injections may develop permanent slits in
the skin
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A cross section of the Brain
These black spots on the brain indicate long-term
drug use
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Skin Rash-common skin condition for addicts who
shoot up
The bottom of the brain
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Hemorrhage caused by a cocaine overdose
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Drug Smuggling
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Hemorrhage caused by a cocaine overdose
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One common way to smuggle drugs into
the country is to swallow a plastic bag
filled with cocaine, heroin, or some
other illegal contraband. After passing
through customs, the smuggler will the
“throw up” the bag. This plan goes
south if the bags burst while in the
stomach.
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The black spots in this stomach indicate where bags of
cocaine burst, causing a massive over dose.
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Toxicology of Alcohol
• The analysis of alcohol exemplifies the primary
objective of forensic toxicology—the detection and
isolation of drugs in the body for the purpose of
determining their influence on human behavior.
• Alcohol, or ethyl alcohol, is a colorless liquid
normally diluted with water and consumed as a
beverage.
• Like any depressant, alcohol principally effects the
central nervous system, particularly the brain.
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Alcohol Levels
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Alcohol Levels
• Alcohol appears in the blood within minutes after it has
been taken by mouth and slowly increases in
concentration while it is being absorbed from the stomach
and the small intestine into the bloodstream.
• When all the alcohol has been absorbed, a maximum
alcohol level is reached in the blood; and the
postabsorption period begins.
• Then the alcohol concentration slowly decreases until a
zero level is again reached.
• Factors such as time taken to consume the drink, the
alcohol content, the amount consumed, and food present
in the stomach determine the rate at which alcohol is
absorbed.
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• Elimination of alcohol throughout the body is
accomplished through oxidation and excretion.
• Oxidation takes place almost entirely in the liver,
while alcohol is excreted unchanged in the breath,
urine, and perspiration.
• The extent to which an individual may be under the
influence of alcohol is usually determined by either
measuring the quantity of alcohol present in the
blood system or by measuring the alcohol content in
the breath.
• Experimental evidence has verified that the amount
of alcohol exhaled in the breath is in direct
proportion to the blood concentration.
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Alcohol and Circulatory System
Breath Testers
• Humans have a closed circulatory system consisting of
a heart, arteries, veins, and capillaries.
• Alcohol is absorbed from the stomach and small
intestines into the blood stream.
• Alcohol is carried to the liver where the process of its
destruction starts.
• Blood, carrying alcohol, moves to the heart and is
pumped to the lungs.
• In the lungs, carbon dioxide and alcohol leave the
blood and oxygen enters the blood in the air sacs
known as alveoli.
• Then the carbon dioxide and alcohol are exhaled
during breathing.
• Breath testers that operate on the principle of
infrared light absorption are becoming increasingly
popular within the law enforcement community.
• Many types of breath testers are designed to capture
a set volume of breath.
• The captured breath is exposed to infrared light.
• It’s the degree of the interaction of the light with
alcohol in the captured breath sample that allows
the instrument to measure a blood alcohol
concentration in breath.
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Field Testing
Gas Chromatography Testing
• Law enforcement officers typically use field
sobriety tests to estimate a motorist’s degree of
physical impairment by alcohol and whether or
not an evidential test for alcohol is justified.
• The horizontal gaze nystagmus test, walk and
turn, and the one-leg stand are all considered
reliable and effective psychophysical tests.
• A portable, handheld, roadside breath tester may
be used to determine a preliminary breathalcohol content.
• Gas chromatography offers the toxicologist the
most widely used approach for determining alcohol
levels in blood.
• Blood must always be drawn under medically
accepted conditions by a qualified individual.
• It is important that a nonalcoholic disinfectant be
applied before the suspect’s skin is penetrated with
a sterile needle or lancet.
• Once blood is removed from an individual, its
preservation is best ensured when it is sealed in an
airtight container after an anticoagulant and a
preservative have been added and stored in a
refrigerator.
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Alcohol and Law
Alcohol and Law
• The American Medical Association and the
National Safety Council have been able to exert
considerable influence in convincing the states to
establish uniform and reasonable blood-alcohol
standards.
• Between 1939 and 1964 a person having a bloodalcohol level in excess of 0.15 percent w/v was to
be considered under the influence, which was
lowered to 0.10 percent by 1965.
• In 1972 the impairment level was recommended
to be lowered again to 0.08 percent w/v.
• Starting in 2003, states that have not adopted the
0.08 percent per se level will lose part of their
federal funds for highway construction.
• To prevent a person’s refusal to take a test for
alcohol consumption, the National Highway Traffic
Safety Administration recommended an “implied
consent” law.
• Adopted by all states by 1973, this law states that
the operation of a motor vehicle on a public
highway automatically carries with it the stipulation
that a driver will submit for a test for alcohol
intoxication if requested or be subject to loss of the
license.
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Role of the Toxicologist
Role of the Toxicologist
• Beyond the analysis of alcohol, the toxicologist is
confronted with a maze of drugs and poisons.
• The toxicologist is originally presented with body
fluids and/or organs and is normally requested to
examine them for the presence of drugs and
poisons.
• Without supportive evidence, such as the victim’s
symptoms, a postmortem pathological
examination, or an examination of the victim’s
personal effects, the toxicologist is forced to use
general screening procedures with the hope of
narrowing thousands of possibilities to one.
• In addition, the toxicologist is not dealing with
drugs at the concentration levels found in
powders and pills, having been dissipated and
distributed throughout the body.
• Furthermore, the body is an active chemistry
laboratory as few substances enter and
completely leave the body in the same chemical
state.
• Last, when and if the toxicologist has surmounted
all of these obstacles, he or she must be prepared
to assess the toxicity of the drug or poison.
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The Analytical Scheme
The Screening Step
• The forensic toxicologist must devise an analytical
scheme that will successfully detect, isolate, and
specifically identify toxic drug substances.
• Once the drug has been extracted from appropriate
biological fluids, tissues, and organs, the forensic
toxicologist can proceed to identify the drug
substance present.
• Drug extraction is generally based on a large
number of drugs being either acidic or basic.
• The strategy used for identifying abused drugs
entails a two-step approach: screening and
confirmation.
• A screening test is normally employed to provide the
analyst with quick insight into the likelihood that a
specimen contains a drug substance.
• Positive results arising from a screening test are
considered to be tentative at best and must be
verified with a confirmation test.
• The most widely used screening tests are thin-layer
chromatography, gas chromatography, and
immunoassay.
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The Confirmation Step
The DRE
• Gas chromatography/mass spectrometry is
generally accepted as the confirmation test of
choice.
• The GC separates the sample into its components,
while the MS represents a unique “fingerprint”
pattern that can be used for identification.
• Once the drug is extracted and identified, the
toxicologist may be required to provide an
opinion on the drug’s effect on an individual’s
natural performance or physical state.
• The Drug Recognition Expert program
incorporates standardized methods for examining
automobile drivers who are suspected of being
under the influence of drugs.
• To ensure that each subject has been tested in a
routine fashion, each DRE must complete a
standard Drug Influence Evaluation form.
• The DRE program usually cannot determine which
specific drug was ingested.
• Hence, it is the production of reliable data from
both the DRE and the forensic toxicologist that is
required to prove drug intoxication.
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Preparing a Sample Space
Thin Layer Chromatography
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• Cut a sheet of paper so it may
hang free within the intended
container
• Mark a sample line ½ inch to an
inch from the bottom
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Starting the Sample
• Place the sheet in a container
with a solvent
• The bottom of the paper should
be submerged into the solvent,
but not above the samples
Place your
samples on
the sheets
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Allow your
samples to run
at least ½ way
up the sample
space
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Allow your samples to dry
Matching Samples
• Note component colors
• Calculate Rf values
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Solvent finish 10 cm
Calculating Rf Values
8 cm
Calculating Rf
Values
Rf value is a ratio of distance a
component sample moves to the
distance the solvent moves
This number is usually expressed
as a decimal
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4 cm
Rf = 4/10
= 0.4
Rf = 8/10
= 0.8
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Starting point
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