Transcript FORENSIC SCIENCE

FORENSIC SCIENCE
Toxicology
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Toxicology
 Study
of poisons or the detection of foreign
substances in the body that can have a toxic
effect such as:
• Alcohol
• Industrial chemicals
• Poisonous gas
• Illegal drugs
• Drug overdoses
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TOXICOLOGY
TYPES:
• Environmental--air, water, soil
• Consumer--foods, cosmetics, drugs
• Medical, clinical, forensic
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Forensic Toxicology
 Postmortem--medical
examiner or coroner
 Criminal--motor vehicle accidents (MVA),
assault, etc.
 Workplace drug testing
 Sports--human and animal
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Why do Toxicology?
Toxicology can:
• Be a cause of death
• Contribute to death
• Cause impairment
• Explain behavior
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OUR STUDY
 Drugs
 Poisons
 Alcohol
Basically, toxicology involves the separation,
detection, identification and measurement of the drug
and/or poison.
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Drugs and Crime
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Definition--a natural or synthetic substance designed
to affect the subject psychologically or
physiologically.
“Controlled substances”--drugs that are restricted by
law
Controlled Substances Act--enacted in 1970 lists
illegal drugs, their category and their penalty for
possession, sale or use.
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Testing
 PDR’s--Physician’s
Desk Reference
 Field Tests--presumptive tests
 Lab Tests--conclusive tests
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PDR’s
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Analysis of Drugs
 Controlled
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Substances Act
Schedule I--heroin, LSD
Schedule II--morphine, methadone
Schedule III--barbiturates, amphetamines
Schedule IV--other stimulates and
depressants
Schedule V--codeine
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DRUG IDENTIFICATION
Screening tests or
presumptive tests
 Color tests
 Microcrystalline test-a reagent is added that
produces a crystalline
precipitate which are
unique for certain
drugs.
Confirmation tests
 Chromatography
 Spectrophotometry
 Mass spectrometry
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Presumptive Color Tests
 Marquis--turns
purple in the presence of
most opium derivatives and orange-brown
with amphetamines
 Dillie-Koppanyi--turns violet-blue in the
presence of barbiturates
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Presumptive Color Tests
 Duquenois-Levine--turns
a purple color in
the presence of marijuana
 Van Urk--turns a blue-purple in the
presence of LSD
 Scott test--color test for cocaine
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Confirmation Tests
Chromatography
 Techniques
for separating mixtures into
their component compounds
 Includes two phases--one mobile and one
stationary that flow past one another
 As the mixture separates it interacts with the
two phases.
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Types of Chromatography
 Paper
 Thin
Layer
 Gas
 Pyrolysis
Gas
 High Pressure Liquid (HPLC)
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Paper Chromatography
Stationary phase-paper
 Mobile phase--a liquid
solvent
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Capillary action moves
the mobile phase
through the stationary
phase
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Thin Layer Chromatography
Stationary phase--a
thin layer of coating
on a sheet of plastic or
glass (usually
aluminum or silica)
 Mobile phase--a liquid
solvent
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from www.lbp.police.uk
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Retention Factor (Rf)
 This
is a number that
represents how far a
compound travels in a
particular solvent
 It is determined by
measuring the distance
the compound traveled
and dividing it by the
distance the solvent
traveled.
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Retention Factor (Rf)
If the Rf value for an unknown compound is
close to or the same as that for the known
compound, the two compounds are most
likely similar or identical (a match)
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Results from Thin Layer
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What was in the
unknown sample?
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Gas Chromatography
Stationary phase--a
solid or very syrupy
liquid lines a tube or
column
 Mobile phase--an inert
gas like nitrogen or
helium
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GC Analysis
 Shows
a peak that is proportional to the
quantity of the substance present
 Uses retention time instead of Rf for the
quantitative analysis
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Retention Time
 Time
between the sample being injected and
when it exits the column reaching the
detector.
 Tm is the time taken for the mobile phase to
pass through the column
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Pyrolysis Gas
Chromatography
 Used
when a sample does not readily
dissolve in a solvent
 If heating this sample decomposes it into
gaseous products, these products can be
analyzed by CGC
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A pyrogram is a visual representation of the
results
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High Pressure Liquid
Chromatography
 Stationary
phase--fine solid particles
 Mobile phase--a liquid solvent
A solvent is pumped through the column as a
sample is injected into it. The sample, as it
moves, is slowed to differing degrees,
depending on its interaction with the
stationary phase. Different components of
the sample mixture are, therefore, separated.
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Liquid Chromatography
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Mass Spectrometry
Gas chromatography has one major drawback--it
does not give a specific identification. By teaming
a gas chromatograph with a mass spectrometer,
this is accomplished.
The mixture is separated first in a gas
chromatograph. The GC column is directly
attached to the mass spectrometer where a beam of
electrons is shot through the sample molecules.
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MS (cont.)
The electrons cause the molecules to lose electrons
and become positively charged. These are unstable
and decompose into many smaller fragments.
These fragments pass through an electric or
magnetic field and are separated according to their
masses.
NO TWO SUBSTANCES PRODUCE THE
SAME FRAGMENTATION PATTERN.
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Example of a GS/MS
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Human Analysis
for Drugs
 Blood
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Liver tissue
 Urine
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Brain tissue
 Vitreous
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Kidney tissue
 Bile
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Spleen tissue
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“If all those buried in our cemeteries
who were poisoned could raise their
hands, we would probably be
shocked by the numbers.
--John Trestrail
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POISONERS in HISTORY
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Olympias—a famous Greek poisoner
Locusta—personal poisoner of Emperor Nero
Lucretia Borgia—father was Pope Alexander VI
Madame Giulia Toffana—committed over 600 successful
poisonings, including two Popes.
Hieronyma Spara—formed a society to teach women how
to murder their husbands
Madame de Brinvilliers and Catherine Deshayes—French
poisoners.
AND many others through modern times.
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Symptoms of Various
Types of Poisoning
Type of Poison
• Caustic Poison (lye)
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Symptom/Evidence
Characteristic burns around the lips
and mouth of the victim
Carbon Monoxide
Red or pink patches on the chest and
thighs. Unusually brighter red lividity
Sulfuric acid
Black vomit
Hydrochloric acid
Greenish-brown vomit
Nitric acid
Yellow vomit
Phosphorous
Coffee brown vomit. Onion or garlic
odor
Cyanide
Burnt almond odor
Arsenic, Mercury
Pronounced diarrhea
Methyl (wood) or
Nausea and vomiting,
Isopropyl (rubbing) alcohol unconsciousness, possibly blindness
Points to Know about a
Poison
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Form
Common color
Characteristic odor
Solubility
Taste
Common sources
Lethal dose
Mechanism
Possible methods of
administration
Time interval of onset of
symptoms.
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Symptoms resulting from an
acute exposure
Symptoms resulting from
chronic exposure
Disease states mimicked by
poisoning
Notes relating to the victim
Specimens from victim
Analytical detection methods
Known toxic levels
Notes pertinent to analysis of
poison
List of cases in which poison
was used
from “Criminal Poisoning” by John Trestrail
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New Terror--Yuschenko
In 2004, Viktor Yushchenko
announced independent candidate
for president of the Ukraine. His
major rival was Prime Minister
Viktor Yanukovych. The
campaign was often bitter,
controversial, and violent, with
accusations of "dirty tricks" from
both sides. Yushchenko became
seriously ill in early September
2004. On December 11, Austrian
doctors confirmed Yushchenko
was poisoned with TCDD dioxin
having had more than 1,000 times
the usual concentration in his
body. This is the second highest
dioxin level ever measured in a
human. No one has ever been
tried for this crime.
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Evidence
 Class
Presumptive or screening tests can be used to
determine that it is a drug.
 Individual
Chromatography, especially in conjunction with
mass spectrometry, will specifically identify a
drug or poison and its components.
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Toxicology
of Alcohol
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Statistics
• Nearly 17,500 automobile deaths in the U.S.
• 40% of all auto fatalities are due to alcohol
• Over 2 million people/year injured, requiring
hospitalization due to alcohol
• Most abused drug; Must be able to test
rapidly/accurately, due to legal needs
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Alcohol--Ethyl Alcohol: C2H5OH
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Toxic--affecting the central nervous system, especially
the brain
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Toxicologists can test for alcohol in body fluids, tissues, organs
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Acts as a depressant
Alcohol appears in blood within minutes of
consumption; 30-90 minutes for full absorption
Detoxification--about 90% in the liver
About 5% is excreted unchanged in breath, perspiration
and urine
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Effects of Increasing Blood
Alcohol
.02 MELLOW FEELING. SLIGHT BODY WARMTH. LESS INHIBITED.
.05 NOTICEABLE RELAXATION. LESS ALERT. LESS SELF-FOCUSED.
COORDINATION IMPAIRMENT BEGINS.
.08 DRUNK DRIVING LIMIT. DEFINITE IMPAIRMENT IN COORDINATION AND
JUDGMENT.
.10 NOISY. POSSIBLE EMBARRASSING BEHAVIOR. MOOD SWINGS.
REDUCTION IN REACTION TIME.
.15 IMPAIRED BALANCE AND MOVEMENT. CLEARLY DRUNK.
.30 MANY LOSE CONSCIOUSNESS
.40 MOST LOSE CONSCIOUSNESS; SOME DIE.
.50 BREATHING STOPS. MANY DIE.
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Rate of Absorption
Depends on:
• amount of alcohol consumed
• the alcohol content of the beverage
• time taken to consume it
• quantity and type of food present in the
stomach
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BAC
Blood Alcohol Content
 Expressed
as percent weight per volume
 Legal limits in most states is 0.08%
 Parameters influencing BAC:
• Body weight
• Alcoholic content
• Number of beverages consumed
• Time between consumption
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BAC
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Burn off rate if 0.015% per hour but can vary
• Male
BAC male = 0.071 x (oz) x (% alcohol)
body weight
• Female
BAC female = 0.085 x (oz) x (% alcohol)
body weight
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Dose-Response Curve
This is a dose-response curve
for ethyl alcohol, the kind of
alcohol in alcoholic
beverages. At low doses the
effects of alcohol are familiar
and are not life-threatening,
but may still be very
dangerous. At higher doses,
alcohol is extremely toxic to
humans and can cause death.
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Field Tests
 Psychophysical tests--3 Basic
Preliminary tests--used to
determine the degree of
suspect’s physical impairment
and whether or not another test
is justified.
Tests
• Horizontal gaze nystagmus
(HGN)--follow a pen or
small flashlight, tracking
left to right with one’s eyes.
In general, wavering at 45
degrees indicates 0.10
BAC.
• Nine Step walk and turn
(WAT): comprehend and
execute two or more simple
instructions at one time.
• One-leg stand (OLS):
maintain balance,
comprehend andexecute
two or more simple
instructions at one time.
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Henry’s Law
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When a volatile chemical is dissolved in a liquid and is brought to equilibrium with
air, there is a fixed ratio between the concentration of the volatile compound in the
air and its concentration in the liquid, and this ratio is constant for a given
THEREFORE, the concentration of
alcohol in breath is proportional to that in the
blood.
temperature.
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This ratio of alcohol in the blood to alcohol in the alveolar air is approximately 2100
In other words 1 ml of blood will contain
nearly the same amount of alcohol as 2100 ml of
breath.
to 1.
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The Breathalyzer
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more practical in the field
collects and measures alcohol content of alveolar
breath
Breath sample mixes with 3 ml of 0.025 %
K2Cr2O7 and 0.025 % silver nitrate in sulfuric
acid and water
2K2Cr2O7 + 3C 2H5H + 8H 2SO4  2Cr2(SO4)3 + 2K2SO4 + 3CH3COOH +
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Potassium dichromate is yellow, as concentration
decreases the light absorption diminishes so the
breathalyzer indirectly measures alcohol
concentration by measuring light absorption of
potassium dichromate before and after the
reaction with alcohol
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Generalizations
During absorption, the concentration of alcohol in
arterial blood will be higher than in venous blood.
Breath test reflects alcohol concentration in the
pulmonary artery.
Breathalyzer also can react with acetone (as found with
diabetics), acetaldehyde, methanol, isopropyl alcohol,
and paraldehyde, but these are toxic and their presence
means the person is in serious medical condition.
Now using an infrared light absorption device with a
digital read-out. Prints out a card for a permanent record.
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REALLY
BAD
IDEA
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