Transcript FORENSIC SCIENCE

FORENSIC SCIENCE
Toxicology
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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
Basically, toxicology involves the separation,
detection, identification and measurement of the drug
and/or poison.
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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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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
 A pyrogram is the 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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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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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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