FORENSIC SCIENCE Toxicology

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FORENSIC SCIENCEToxicology
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(No Transcript)
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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

• 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

• PDRs--Physicians Desk Reference
• Field Tests--presumptive tests
• Lab Tests--conclusive tests

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PDRs
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Analysis of Drugs

• Controlled 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 TestsChromatography

• 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
• 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

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

• 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 LiquidChromatography

• 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 Analysisfor Drugs

• Blood
• Urine
• Vitreous
• Bile

• Liver tissue
• Brain tissue
• Kidney tissue
• 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

• Olympiasa famous Greek poisoner
• Locustapersonal poisoner of Emperor Nero
• Lucretia Borgiafather was Pope Alexander VI
• Madame Giulia Toffanacommitted over 600
  successful poisonings, including two Popes.
• Hieronyma Sparaformed a society to teach women
  how to murder their husbands
• Madame de Brinvilliers and Catherine
  DeshayesFrench poisoners.
• AND many others through modern times.

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Symptoms of VariousTypes of Poisoning

• Type of Poison Symptom/Evidence
• Caustic Poison (lye) 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

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Points to Know about aPoison

• Form
• Common color
• Characteristic odor
• Solubility
• Taste
• Common sources
• Lethal dose
• Mechanism
• Possible methods of administration
• Time interval of onset of symptoms.

• 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

• Toxic--affecting the central nervous system,
  especially the brain
• Toxicologists can test for alcohol in body
  fluids, tissues, organs
• 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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BACBlood 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

• 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 Tests
• Horizontal gaze nystagmus (HGN)--follow a pen or
  small flashlight, tracking left to right with
  ones 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.

• Preliminary tests--used to determine the degree
  of suspects physical impairment and whether or
  not another test is justified.

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Henrys Law

• 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 temperature. THEREFORE, the
  concentration of alcohol in breath is
  proportional to that in the blood.
• This ratio of alcohol in the blood to alcohol in
  the alveolar air is approximately 2100 to 1. In
  other words 1 ml of blood will contain nearly the
  same amount of alcohol as 2100 ml of breath.

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The Breathalyzer

• 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 11 H2O
• 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