Forensic Chemistry and
Toxicology
1
Toxicology
• Formed from the Greek words
toxicos and logos, toxicology is
the study of the symptoms,
mechanisms, treatments and
detection of poisoning
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2
Vocabulary
• Forensic toxicology centers on
the determination of toxic
substances in human tissues,
organs and body fluids such as urine
and blood, and the subsequent
determination of the role any toxic
agents may have contributed to or
caused death.
3
Toxicology
• Toxin is any material that is considered
to have a life threatening effect on a
living organism.
• Poison is a subgroup of toxins
- comes in many forms
• Gaseous
• Animals
Liquid
Minerals
Solid
Vegetables
Enters Body 1 of 3 ways: Ingested
Inhaled
Absorbed into the skin
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Toxicology
Types of toxicologists
• Descriptive Toxicologist: Performs
toxicity test to evaluate the risk that
exposure pose to humans
• Mechanistic Toxicologist: attempts to
determine how substances exert
deleterious effects on living organisms.
• Regulatory Toxicology: Determines
whether or not a substance has low
enough risk to justify making it available
to the public. Forensic Toxicology is a
subspecialty
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Provide Answers to “?”
Forensic Toxicologists:
• Provide answers to questions that may
be asked during the investigation or at
a subsequent legal hearing.
– Was a poison involved in the case?
– If so, what was the nature of the poison
– how was it administered
– was it at a potentially lethal concentration?
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Forensic Toxicology
What do they Investigate?
• Accidental Poisoning
• Drug Abuse/Overdose
• Suicidal/Homicidal Poisoning
• *75% of the evidence
evaluated in the crime
lab is drug related!
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16th Century Physician
Paracelsus
“All substances are poisons; there is
none which is not a poison. The right
dose differentiates a poison from a
remedy.”
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Vocabulary of the Chemist
• Poison: a
substance taken
in sufficient
quantity to
cause ill health
or death
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Vocabulary
2 classes of toxicity: acute and chronic.
• Acute toxicity refers to effects that occur
shortly after a single exposure or small
number of closely spaced exposures.
• Chronic toxicity refers to delayed effects
that occur after long term repeated
exposures.
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Common Toxins / Poisons
Acids(HNO3, HCl, H2SO4)
Burns around mouth, lips, nose
Aniline(hypnotics,
nitrobenzene)
Skin of face & neck quite dark
As(metals, Hg, Cu, Pb)
Severe, unexplained diarrhea
Atropine(Belladonna),
Scopolamine
Pupil of eyes dilated
Bases(lye, potash, OH-)
Burns around mouth, lips, nose
Carbolic Acid (phenols)
Odor of disinfectant
CO
Skin is bright cherry red
HCN
Red skin, odor of peach, Quick
Food poisoning
Vomiting, abdominal pain
Metallic compounds
Diarrhea, vomiting, abdominal pain
Nicotine
Convulsions
Opiates
Pupil of eyes contracted
Oxalic acid (P-)
Odor of garlic
NaF
Convulsion
Strychnine
Convulsion, dark face & neck
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Poisonings
• Children under 6 account for most of the
reported poisonings/year
• About 700 deaths by poisoning are
reported each year
• Approximately 2 million cases are
voluntarily reported to poison control
centers each year
• However adults account for the majority
of deaths by poisoning most of which is
intentional rather than accidental
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Toxins/Poisons
Most Reported
1 - Household cleaning supplies
2 - Analgesics (aspirin, acetaminophen)
3 - Cosmetics
4 - Cough & cold remedies
5 - Plant scrapes & insect bites
6 - Pesticides
7 - Topical creams & lotions
8 - Hydrocarbons i.e. gasoline, kerosene
9 - Anti-micro bacterial soaps
10 - Sedatives/hypnotics/anti-psychotics
11 - Food poisoning
12 - Alcohol
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Toxins/Poisons
Most Frequent Deaths
1 – Antidepressant medications
2 - Analgesics (aspirin, acetaminophen)
3 - Street drugs
4 - Cardiovascular drugs
5 - Alcohol
6 - Gases and fumes
7 - Asthma therapies
8 - Industrial chemicals
9 - Pesticides
10 - Household cleaning supplies
11 - Anticonvulsant medications
12 - Food, plants, & insects
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Pharmacokinetics &
Pharmacodynamics
Pharmacokinetics is the
relationship between drug conc.
In the body & time after
administration of the drug. Form,
frequency & route all have an
effect on this
Pharmacodynamics is the study
of the biochemical &
physiological effects of a drug
and its mechanism of action.
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Drug Absorption from the GI tract is
dependent on the rate & amount of intact
drug and the rate that it reaches circulation
after oral administration. Rate is affected by:

Solubility

Absorption across membrane

Gastric emptying

Metabolic Rate
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Structure of GI Tract
The GI tract has three major
regions: the stomach, small
intestine and the large
intestine.
Stomach – the mucosa contains
many folds that increase the
surface area available for drug
absorption. The high blood supply
and the fact that a drug can
potentially reside in the stomach
for several hours can provide
optimum conditions for the
absorption of acidic drugs.
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Structure of GI Tract
• Small Intestine - the most important GI site
for drug absorption. The intestinal mucosa
provides an extremely large surface area; villi
and microvilli aids drug absorption (about 30’
long in an adult)
• Large Intestine - like the stomach, lacks the
villi and microvilli of the small intestine; serves
as a site for the absorption of drug that has
not been completely absorbed in the small
intestine. (about 6’ long in an adult)
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Mechanisms of Drug Transport
Across the GI Barrier
• The majority of drugs cross the membrane by
passive diffusion.
• Passive Diffusion - Drug transport rate is determined by
the physical and chemical properties of the drug, and its
concentration gradient across the membrane. Drug
entering the blood stream will be carried away from the
site of absorption by the gastrointestinal blood supply and
will become diluted by:
– Distribution in a large volume of blood.
– Distribution into body tissue.
– Metabolism and excretion.
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– Protein binding in the blood.
Physiological Factors
Influencing Drug Absorption
• Surface area of the absorption site
• pH of the GI fluids
• Gastric emptying rate: can be stimulated by
hunger, anxiety, body position and liquid
consumption; Fatty foods, high bulk diet,
depression and various drugs and alcohol
retard it.
–
–
–
–
Intestinal motility
Drug stability in the GI system
Dietary components
Disease states
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Drug Metabolism
• Metabolism is the fundamental mechanism of
drug elimination. Metabolism aids drug
excretion processes and may affect the
pharmacological response of a drug by
altering its potency and/or duration of action
• Metabolism can occur in the plasma as well
as organs other than the liver such as the GI
tract, kidneys and lungs.
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Factors Affecting
Metabolism
• Age
Young children and elderly people usually have
a lower metabolic capacity
• Disease
Diseases can affect all of the ADME
processes. Liver and kidney diseases probably
have the greatest effect on drug concentrations
by affecting metabolism and excretion.
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Factors Affecting
Metabolism
• Weight
The weight of a patient affects drug concentrations in the
blood since it determines the volume into which the drug
is distributed. Drug metabolism tends to be faster in
males than in females.
• Genetic Factors
Gender and race differences in enzyme activity can affect
drug metabolism
• Diet
Diet may influence the metabolism of some drugs.
Exposure to other drugs (particularly alcohol) markedly
affects the metabolism of certain drugs.
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Excretion of Drugs
• The excretion of drugs and metabolites
terminates their activity and presence in the
body. Elimination can occur by various routes.
The kidney plays a major role with the
excretion of drugs and/or their metabolites into
the urine. Drugs may also be excreted in the
feces, bile, lungs sweat, saliva and breast milk.
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What is a drug?
• 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.
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Illicit Drugs
• “NIDA 9”
– Methamphetamine
– Cocaine
– Opiate
– Benzodiazepam
– Amphetamine
– THC
– Methadone
– Barbiturates
– PCP
• CNS Depressants:
– Narcotics (opiates)
– Sedatives, hypnotics
(PCP, Quaalude)
– Tranquilizers (Valium)
• CNS Stimulants
– Cocaine
– Amphetamines
• Hallucinogens
– Mescaline, psilocybin,
LSD, PCP
– THC
• Steroids
• Inhalants
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Illicit Drug Use
• The hazards of illicit drug use are
the increase in infections, disease,
and overdose
• Medical complications that are
commonly seen among addicts are
brain, skin, and lung abscesses;
inflammation of the lining of the
heart, hepatitis, and AIDS.
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Signs of an Overdose
•
•
•
•
•
•
Respiratory depression
cold clammy skin
Confusion
Convulsions
Severe drowsiness
Constricted pupils
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Hallucinogens
• A 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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Abused Drug Timetables
Hallucinogens/Opiates
Drug/Commercial & Street Names
Administered/Detection in Urine*
Cannabinoids
Marijuana
Blunt, dope, ganja, grass,
herb, joints, Mary Jane,
pot, reefer, sinsemilla,
skunk, weed
Swallowed, Smoked
14 days - 11weeks
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Hallucinogins
Cannabinoids – Marijuana
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
– the risk of harm is in heavy, long-term use.
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Hallucinogens
• Drug/Commercial & Street Names
Administered/Detection in Urine*
Hashish
Boom, chronic, gangster,
hash, hash oil, hemp
Swallowed, Smoked
14 days - 11weeks
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Other Hallucinogens
• Other hallucinogens include LSD, mescaline, PCP,
psilocybin, & MDMA (Ecstasy).
• LSD is synthesized from lysergic acid, & can
cause hallucinations that can last for 12 hours.
• Phencyclidine, or PCP, is often synthesized in
clandestine laboratories & is often smoked,
ingested, or sniffed.
• PCP is often mixed with other drugs, such as LSD,
or amphetamine, & 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, & suicide.
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Opiates
• 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.
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Opiates
• 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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Abused Drugs Timetable
Depressants/Barbituates
• Drug/Commercial & Street Names
Administered/Detection in Urine*
Depressants
Barbiturates
Amytal, Nembutal, Seconal,
Phenobarbital:
barbs, reds, red birds,
phennies, tooies, yellows,
yellow jackests
Injected, swallowed
2-10 days
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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.
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Depressants
• 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 highthinking 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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Abused Drugs Timetable
• Drug/Commercial & Street Names
Administered/Detection in Urine*
•
Benzodiazepine
Anesthetics/PCP
Ativan, Halcion, Librium, Phencyclidine: angel
Valium, Xanax: candy,
dust, downers,
boat, hog, love boat,
sleeping pills, peace
tanks
pill
• Injected, swallowed
Injected, swallowed,
smoked
1-6 weeks
7-14 days
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Abused Drugs Timetable
• Drug/Commercial & Street Names
Administered/Detection in Urine*
Opioids & Morphine/Codeine
Empirin with Codeine, Fiorinal with Codeine,
Robitussin A-C, Tylenol with Codeine:
Captain Cody, Cody, schoolboy, doors &
fours, loads, pancakes & syrup
Injected, swallowed
2-4 days
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Abused Drugs Timetable
• Drug/Commercial & Street Names
Administered/Detection in Urine*
Fentanyl
Actiq, Duragesic, Sublimaze:
Apache, China girl, China white, dance
fever, friend, goodfella, jackpot, murder 8, TNT,
Tango and Cash
Injected, smoked, snorted
8-24 hours
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Abused Drugs Timetable
Heroine
(first synthesized In 1874) diacetylmorphine:
brown sugar, dope, H, horse, junk, skag,
skunk, smack, white horse
Injected, smoked, snorted
2-4 days
Morphine
Roxanol, Duramorph:
M, Miss Emma, monkey, white stuff
Injected, swallowed, smoked
2-4 days
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Heroin Usage
• In 1974 estimated users were 246,000.
• Between the years 1988-1994 there were an
estimate of 28,000-80,000 new users
• Between 1995 and 2001 the number of new
users was greater than 100,000
• Today there has been a reported 3.7 million
people in the US alone who reported using
heroin at least once in their lifetime.
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Abused Drugs Timetable
Opium
Laudanum, Paregoric:
big O, black stuff, block, gum, hop
Swallowed, smoked
2-4 days
Oxycodone
Oxycontine: Oxy, O.C., killer
Swallowed, snorted, injected
8-24 hours
OXY Hydrocodone Bitartrate
Vicodin: vike, Watson-387
Swallowed
1-6 days
44
Oxycodone
• In 1993 3.5 tons of Oxycodone were
manufactured for sale in the United
States
• 2003 41 tons were manufactured
• The tablet is either taken orally or
crushed and sniffed or dissolved in water
and injected
• This drug is often stolen and
prescriptions are often forged
45
Hydrocodone
• It is used as a cough suppressant and
analgesic
• DEA has this drug listed as the most
frequently encountered opiate
pharmaceutical that is submitted for drug
evidence to federal, state and local forensic
laboratories.
• Abusers obtain the is drug by theft, doctor
shopping, fraudulent prescriptions, and fake
call in prescriptions
46
Abused Drugs Timetable
Methadone
Dolophine, Methadone
Swallowed, Injected
6-12 days
Buprenorphine
Subutex, Buprenex, Temgesic, Suboxone
Swallowed, Injected
1-6 days
47
Dextropropoxyphene
•
•
•
•
Related to Morphine
First marketed in 1957
Used to help moderate to mild pain
There is 150 tons produced in the United
States annually
• 25 million prescriptions have been written.
• This drug is among the top 10 drugs reported
by the medical examiner in drug abuse deaths.
48
Abused Drugs Timetable
Stimulants:
Amphetamine
Biphetamine, Dexedrine:
bennies, black beauties, crosses, hearts, LA
turnaround, speed, truck driver, uppers
Injected, swallowed,
smoked, snorted
1-3 days
Methamphetamine
Desoxyn:
chalk, crank, crystal, fire, glass, go fast, ice,
meth, speed; Injected, swallowed, smoked,
snorted
3-5 days
49
Stimulants
• 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.
50
Stimulants
• Amphetamine and methamphetamine, often
injected intravenously, causes an initial “rush,”
followed by an intense feeling of pleasure.
– 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.
51
Abused Drugs Timetable
Cocaine
Cocaine hydrochloride:
blow, bump, C, candy, Charlie, coke, crack,
flake, rock, snow, toot
Injected, smoked, snorted
2-7 days
52
Date Rape Drugs
• 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 drug-facilitated sexual assault, rape, and
robbery.
53
Date Rape Drugs
• Ecstasy
Adam, clarity, ecstasy, lover's
speed, peace, STP, X, XTC
Swallowed
• Referred to as party drugs
• Are commonly found at bars, night
clubs, raves and techno parties.
• Causes a comma in 30- 40 minutes
• Associated with sexual assaults
54
Date Rape Drugs
• 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.
55
Date Rape Drugs
• 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.
56
Abused Drugs Timetable
Nicotine
Cigarettes, cigars, smokeless tobacco, snuff,
spit tobacco, bidis, chew
Smoked, Snorted, taken in snuff &
spit tobacco
4-30 days
Alcohol
Alcohol
Beer, Wine, Liquor
Swallowed
6 Hrs- 2 days
57
Alcohol Related Deaths
• Of the 40,000 auto accidents in the
United States
– 50% are drunk drivers
– 60% of pedestrians killed have high
blood alcohol levels
58
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.
59
Alcohol Levels
• Alcohol appears in the blood within minutes
after it has been taken by mouth & slowly
increases in concentration while it is being
absorbed from the stomach & the small intestine
into the bloodstream.
• When all alcohol has been absorbed, a max
alcohol level is reached in the blood; and the
post-absorption period begins.
• The alcohol concentration slowly decreases
until a zero level is again reached.
60
Alcohol Levels
Factors affecting outcome on individual
consumption:
1. Time taken to consume the drink
2. Alcohol content
3. Amount consumed
4. Food presence in the stomach
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.
61
Alcohol Levels
• Elimination of alcohol throughout the body is
accomplished through oxidation & excretion.
• Oxidation takes place almost entirely in the
liver, while alcohol is excreted unchanged in
the breath, urine, and perspiration.
• Experimental evidence has verified that the
amount of alcohol exhaled in the breath is in
direct proportion to the blood concentration.
62
Alcohol & the Circulatory
System
• 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 CO2 & alcohol are exhaled during
breathing.
63
Alcohol Breath Testers
• Breath testers that operate on the principle of IR
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.
• Captured breath is exposed to IR 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 alc. conc. in
breath.
64
Alcohol Field 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.
65
Alcohol and the Law
• The AMA. & the National Safety Council have
been able to exert considerable influence in
convincing the states to establish uniform &
reasonable blood-alcohol standards.
• Between 1939 and 1964 a person having a
blood-alcohol 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.
66
Alcohol and Law
• Starting in 2003, states adopted the 0.08 percent
per se level.
• 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.
67
Collection and Preservation of
Blood for Alcohol Testing
• Blood must always be drawn under
medically accepted conditions by a
qualified individual.
• It is important to apply a nonalcoholic
disinfectant before the suspect’s skin is
penetrated with a sterile needle or lancet.
• Once blood is removed from an individual,
it is best preserved sealed in an airtight
container after adding an anticoagulant
and a preservative.
68
Field 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
breath-alcohol content.
69
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.
70
Drug Control Laws
• The U.S. federal law known as the Controlled
Substances Act will serve to illustrate a legal
drug-classification system created to prevent
and control drug abuse. - 1970
• This federal law establishes five schedules of
classification for controlled dangerous
substances on the basis of a drug’s:
– potential for abuse
– potential for physical and psychological dependence
– medical value
71
Schedules of Classification
• Schedule I drugs have
a high potential for
abuse and have no
currently accepted
medical use such as
heroin, marijuana,
methaqualone and
LSD.
72
Schedules of Classification
• Schedule II drugs have a high potential
for abuse and have medical use with
severe restrictions such as cocaine, PCP,
and most amphetamine and barbiturate
prescriptions.
73
Schedules of Classification
• Schedule III drugs have less potential for
abuse and a currently accepted medical
use such as all barbiturate prescriptions
not covered under Schedule II, codeine,
and anabolic steroids.
74
Schedule of Classification
• Schedule IV drugs have a low potential for
abuse and have a current medical use such
as darvon, phenobarbital, and some
tranquilizers such as diazepam (valium) and
chlordiazepoxide (librium).
• Schedule V drugs must show low abuse
potential and have medical use such as
opiate drug mixtures that contain
nonnarcotic medicinal ingredients.
75
Collection & Preservation
• Generally common sense is the best guide,
keeping in mind that the package must
prevent the loss of the contents and/or crosscontamination.
• Often the original container in which the drug
was seized will suffice.
• 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.
76
Collecting for the Lab
Who does what?
First responder prepares specimen for lab
• Controlled Substance Analyst
• Poison Analyst
77
Role of the Toxicologist
• The toxicologist is not dealing with drugs
at the concentration levels found in
powders and pills, having been dissipated
and distributed throughout the body.
• 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.
78
Drug Identification
• 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.
– 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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Screening Tests
• 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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Types of Toxicologist Tests
Screening Tests
• Physical Tests: boiling point, melting point,
density, and refractive index
• Crystal Tests: treatment with a chemical
reagent to produce crystals
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Types of Toxicologist Tests
Screening Tests
• Chemical Spot Tests: treatment with a
chemical reagent to produce color changes
• Chromatography (thin-layer or gas): used
to separate components of a mixture
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Confirmatory Tests
• Gas chromatography/mass spectrometry
GC/MS 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.
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Abused Drugs Timetable
*Detection time in
SPOT TEST
urine is an average
and can vary
Methamphetamine - Test Kit
greatly. Detection
time can vary due to
length and amount of
Marquis
use.
Reagent
Different testing
panels may have
more then one
combination of tests.
Sodium
Nitroprusside
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The Analytical Scheme
• 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.
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Analytical
Instrumentation
• Specific/ Non-specific:
Stimulant vs. Depressant
Exact ID of the drug
• Destructive/Non-destructive:
Sample consumed, further testing
• Instrumentation: GC/MS
FTIR
Chromatography
• Chromatography is a means of separating and
tentatively identifying the components of a
mixture.
• The theory of chromatography is based on the
observation that chemical substances have a
tendency to partially escape into the
surrounding environment when dissolved in a
liquid or when absorbed on a solid surface.
• Those materials that have a preference for the
moving phase will slowly pull ahead and
separate from those substances that prefer to
remain in the stationary phase.
87
TLC
• TLC uses a solid stationary phase usually coated onto a
glass plate and a mobile liquid phase to separate the
components of the mixture.
• The liquid will slowly rise up the plate by capillary action
causing the sample to become distributed between the
stationary phase and the moving liquid phase.
• Because most compounds are colorless, the materials
must be visualized by placing the plates under
ultraviolet light or spraying the plate with a chemical
reagent.
• The distance a spot travels up a thin-layer plate can be
assigned a numerical value known as the Rf value.
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GC/MS
• Destructive, Specific
• Chromatography: selective
separation of components of a
sample
• GC separates
• MS identifies and
quantitates
*Forensic Labs use
GC methods to test
for blood alcohols
GC/MS
• Chromatography: selective
separation of components of a
sample
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Gas Chromatography
In GC: 2 phases
• The moving phase.
• The stationary phase
After a mixture has traversed the length of the
column, it will emerge separated into its
components.
• The written record of this separation is called a
chromatogram.
• The time required for a component to go through
a GC column is known as retention time.
91
Gas Chromatography
• Sample diluted in solvent
• Injected into capillary column
• Heat vaporizes sample, travels
through column
• Detector records time it takes to move
through column (retention time)
• Data (chromatogram) compared to
known substances
92
93
Gas Chromatography –
Chromatograms
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Theory of Light
• Light is described as a continuous wave.
• When white light passes though a prism, it is dispersed
into a continuous spectrum of colors.
• Waves are described in terms such as:
– Wavelength, the distance between two successive
crests (or one trough to the next trough).
– Frequency, the number of crests (or troughs) passing
any one given point per unit of time.
• The electromagnetic spectrum is the entire range of
radiation energy from the most energetic cosmic rays to
the least energetic radio waves.
– Visible light is only a small part of the
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electromagnetic spectrum.
Spectrophotometry
• Just as a substance can absorb visible light to
produce color, many of the invisible radiations of
the electromagnetic spectrum are likewise
absorbed.
• Spectrophotometry, an important analytical tool,
measures the quantity of radiation that a
particular material absorbs as a function of
wavelength and frequency.
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UVand IR
Spectrophotometry
• Most forensic laboratories use UV and IR
spectrophotometers to characterize chemical
compounds.
• The simplicity of the UV spectrum facilitates its use
as a tool for determining a material’s probable
identity. May not provide a definitive result.
• The IR spectrum provides a far more complex
pattern.
• Different materials always have distinctively different
IR spectra; each IR spectrum is therefore equivalent
to a “fingerprint” of that substance.
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Mass Spectrometry
• In the mass spectrometer, a beam of highenergy electrons collide with a material,
producing positively charged ions.
• These positive ions almost instantaneously
decompose into numerous fragments, which
are separated according to their masses.
• The unique feature of mass spectrometry is
that under carefully controlled conditions, no
two substances produce the same
fragmentation pattern.
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GC and Mass
• A direct connection between the GC column
and the mass spectrometer allows each
component to flow into the mass spectrometer
as it emerges from the GC.
• The separation of a mixture’s components is
first accomplished by the GC.
• Then, fragmentation of each component by
high-energy electrons in the mass
spectrometer, will produce a distinct pattern,
somewhat like a “fingerprint”, of the substance
being examined.
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FTIR
• Non-destructive, specific
• Visible light is made of
electromagnetic waves, seen as
colors…IR is in the spectrum, we
just can’t see
• Works by measuring degree of
absorption of IR waves of certain
frequencies
• Works only with pure samples
100
FTIR - Printouts
Cocaine
Heroin
101
Drug Recognition Expert (DRE)
• During the 1970s, the Los Angeles Police Department
developed clinical and psychophysical examinations
that a trained police officer could use to identify and
differentiate between types of drug impairment.
• This program has evolved into a national program to
train police as drug recognition experts.
• Normally, a three- to five-month training program is
required to certify an officer as a drug recognition
expert (DRE).
• The DRE program incorporates standardized
methods for examining suspects to determine
whether they have taken one or more drugs.
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Toxicity
• Water can cause fatal electrolyte
imbalances
• Arsenic and cyanide are harmless in
small doses
103
Marsh Arsenic Test
• Developed by James Marsh in 1836
• When Zn and acid react with arsenic,
gas released that deposits metallic
arsenic when burned
• Use of arsenic for poisoning so
prevalent that nicknamed “inheritance
powder”
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Specimens for Analysis
•
•
•
•
•
•
•
•
Adipose Tissue
Bile
Blood
Brain
Kidney
Liver
Lung
Stomach/Intestine
Contents
• Urine
• Vitreous Humor
Insecticides, Thiopental
Codeine, Morphine
Alcohols, CO
Volatile Poisons
Heavy metal
Most Toxicants
Methadone, Gases, Inhalants
All toxicants taken orally
Most Toxicants
Digoxin, electrolytes, glucose
105
Detecting Drugs in Hair
• Drugs present in blood diffuse through the
capillary walls into the base of the hair and
become permanently entrapped in the hair’s
hardening protein structure.
• As the hair continues to grow, the drug’s
location on the hair shaft becomes a historical
marker for delineating drug intake.
• Given that the average human head hair grows
at the rate of 1 centimeter per month, analyzing
segments of hair for drug content may define
the timeline for drug use.
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Drug Identification
• 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.
– 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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Preliminary Analysis
• The unknown substance may be any one of a
thousand or more commonly encountered drugs, the
analyst employs 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 commonly
encountered illicit drugs.
• Microcrystalline tests can also be used to identify
specific drug substances by studying the size and
shape of crystals formed
108
Conformational
Determination
• Once this preliminary analysis is completed, a
conformational 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 gas
chromatography-mass spectrometry is used to
specifically identify a drug substance.
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Qualitative vs. Quantitative
• Another consideration in selecting an
analytical technique is the need for
either a qualitative or a quantitative
determination.
• The former relates just to the identity of
the material, whereas the latter requires
the determination of the percent
composition of the components of a
mixture.
110
The Screening Step
• 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.
111
The Confirmation Step
• 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.
112
Nondrug Poisons
• Heavy metals such as arsenic, bismuth, antimony,
mercury, and thallium are only occasionally
encountered because severe environmental protection
regulations restrict their availability to the general
public.
• Carbon monoxide is one of the most common poisons
encountered in a forensic laboratory.
• To measure the concentration of carbon monoxide in
the blood spectrophotometric methods determine the
amount of carboxyhemoglobin relative to
oxyhemoglobin or total hemoglobin; or a volume of
blood can be treated with a reagent to liberate the
carbon monoxide, which is then measured by gas
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chromatography.
Significance of Findings
• Once a drug is found and identified, the
toxicologist determines its influence on the
behavior of the individual.
• For many drugs, blood concentration levels
are readily known and are used to estimate
the pharmacological effects of the drug on the
individual.
• When dealing with a living person, the
toxicologist has the added benefit of knowing
what a police officer may have observed
about an individual’s behavior and motor
skills.
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ELISA Template –
Confirmatory testing
•
•
•
Uses antibodies and enzymes to
bind to drug of interest
Qualitative, not quantitative
Specific
115
Well Plates – basic tests
• Come pre-coated with specific drug
antigens
• Add sample
• Add conjugate, incubate
– Antibody-enzyme complex that binds primary
antibody
– For drug testing, drugs will occupy that spot
so the conjugate cannot bind
• Wash plate, add substrate (produces
color change if bound to conjugate)
• Add stop, stops reaction from continuing,
read plate with UV-Vis
116
Testing Sample Sources
What types of samples do forensic toxicologist take for
analysis?
Urine
Blood
Hair
Maggots
Bacteria
Anthrax
Other
body
fluids
117
Results:
• A clear well indicates the presence
of the drug (The drug bound to the plate,
prevented conjugate from binding so substrate
couldn’t bind and produce a color change)
• A yellow well indicates the absence
of the drug (conjugate bound to plate,
substrate bound and produced color change)
• Negative Calibrators, +/- Controls,
and Cutoff Calibrator
118
How many test + on this plate?
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Video Segment: Love Thy Neighbor
Dr. Michael Baden
Board-certified,
Forensic Pathologist
Love Thy Neighbor
In 1988, 42-year-old Peggy Carr, a two-time divorcee on her third
marriage, was hospitalized in Florida & eventually diagnosed with
Thallium poisoning; she later slipped into a coma and died. The
woman's two sons also became gravely ill from Thallium poisoning.
In scouring the family's home, police found several empty Coke
bottles that tested positive for Thallium.
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