Transcript Science Fair Project

Chapter 7
Drugs
“Having sniffed the dead man’s lips, I detected a
slightly sour smell, and I came to the conclusion that
he had poison forced upon him.”
—Sherlock Holmes, in Sir Arthur Conan Doyle’s
A Study in Scarlet
Drugs and Crime
 A drug is a natural or synthetic substance designed
to affect the subject psychologically or
physiologically.
 “Controlled substances” are drugs that are
restricted by law
 Controlled Substances Act is a law that was
enacted in 1970; it lists illegal drugs, their category
and their penalty for possession, sale or use.
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Controlled Substances Act
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Schedule I—high potential for abuse; no currently acceptable
medical use in the US; a lack of accepted safety for use under
medical supervision
Schedule II—high potential for abuse; a currently accepted
medical use with severe restrictions; abuse may lead to severe
psychological or physical dependence
Schedule III—lower potential for abuse than the drugs in I or II; a
currently accepted medical use in the US; abuse may lead to
moderate physical dependence or high psychological dependence
Schedule IV—low potential for abuse relative to drugs in III; a
currently accepted medical use in the US; abuse may lead to
limited physical or psychological dependence relative to drugs in III
Schedule V—low potential for abuse relative to drugs in IV;
currently accepted medical use in the US; abuse may lead to
limited physical or psychological dependence relative to drugs in IV
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Examples of Controlled Substances and Their
Schedule Placement
 Schedule I—heroin (diacetylmorphine), LSD, marijuana,
ecstasy (MDMA)
 Schedule II—cocaine, morphine, amphetamines (including
methamphetamines), PCP, Ritalin
 Schedule III—intermediate acting barbiturates, anabolic
steroids, ketamine
 Schedule IV—other stimulants and depressants including
Valium, Xanan, Librium, phenobarbital, Darvon
 Schedule V—codeine found in low doses in cough medicines
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Human Components
Used for Drug Analysis
 Blood
 Liver tissue
 Urine
 Brain tissue
 Hair
 Kidney tissue
 Gastric Contents
 Spleen tissue
 Bile
 Vitreous Humor of the
Eye
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Identification of Drugs
 PDR—Physicians’ Desk Reference
 Field Tests—presumptive tests
 Laboratory Tests—conclusive
tests
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Physicians’ Desk Reference
PDR—a physicians’ desk reference is used
to identify manufactured pills, tablets and
capsules. It is updated each year. This
can sometimes be a quick and easy
identifier of the legally made drugs that
may be found at a scene. The reference
book gives a picture of the drug, whether it
is a prescription, over the counter, or a
controlled substance; as well as more
detailed information about the drug.
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Drug Identification
Screening or presumptive tests
 Spot or color tests
 Microcrystalline test—
a reagent is added that produces a crystalline precipitate which
is unique for a certain drug.
 Chromatography
Confirmatory tests
 Spectrophotometry
 Ultraviolet (UV)
 Visible
 Infrared (IR)
 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
 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,
blue
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Chromatography
 A technique for separating mixtures into
their components
 Includes two phases—a mobile one that
flows past a stationary one.
 The mixture interacts with the stationary
phase and separates.
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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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Spectroscopy
 Spectroscopy—the interaction of electromagnetic
radiation with matter.
 Spectrophotometer—an instrument used to measure
and record the absorption spectrum of a chemical
substance.
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Spectrophotometry
Components
 A radiation source
 A frequency selector
 A sample holder
 A detector to convert electromagnetic
radiation into an electrical signal
 A recorder to produce a record of the signal
Types
 Ultraviolet
 Visible
 Infrared
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Infrared Spectometry
 Material absorbs energy in the near-IR region of the electromagnetic
spectrum.
 Compares the IR light beam before and after passing through a
transparent sample.
 Result—an absorption or transmittance spectrum
 Gives a unique view of the substance; like a fingerprint
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Mass Spectrometry
Gas chromatography has one major drawback, it does
not give a specific identification. Mass spectrometry
cannot separate mixtures. By combining the two (GCMS),
constituents of mixtures can be specifically identified.
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Mass Spectrometry
In a mass spectrometer, an electron
beam is directed at sample molecules in
a vacuum chamber. The electrons break
apart the sample molecules into many
positive charged fragments. These are
sorted and collected according to their
mass-to-charge ratio by an oscillating
electric or a magnetic field.
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Mass Spectra
Each molecular species has its own
unique mass spectrum.
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IR Spectrophotometry and
Mass Spectrometry
 Both work well in identifying pure
substances.
 Mixtures are difficult to identify in both
techniques
 Both are compared to a catalog of knowns
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Chapter 8
Toxicology:
Poisons and Alcohol
“All substances are poisons.
There is none which is not.
The right dose differentiates
a poison and remedy.”
—Paracelsus (1495-1541). Swiss
physician and chemist
—Jhn Trestrail from “Criminal Poisoning”
Toxicology
Definition—the study of the adverse effects
of chemicals or physical agents on living
organisms.
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)
 Workplace—drug testing
 Sports—human and animal
 Environment—industrial, catastrophic,
terrorism
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Toxicology
Toxic substances may:
 Be a cause of death
 Contribute to death
 Cause impairment
 Explain behavior
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The Severity of the Problem
“If all those buried in our cemeteries who
were poisoned could raise their hands,
we would probably be shocked by the
numbers.”
—John Harris Trestrail, “Criminal Poisoning”
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Aspects of Toxicity
 Dosage
 The chemical or physical form of the substance
 The mode of entry into the body
 Body weight and physiological conditions of the
victim, including age and sex
 The time period of exposure
 The presence of other chemicals in the body or
in the dose
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Lethal Dose
 LD50—refers to the dose of a substance
that kills half the test population, usually
within four hours
 Expressed in milligrams of substance per
kilogram of body weight
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Toxicity Classes
LD50 (rat,oral)
Correlation to Ingestion
by 150 lb Adult Human
Toxicity
<1mg/kg
a taste to a drop
extremely
1-50 mg/kg
to a teaspoon
highly
50-500 mg/kg
to an ounce
moderately
500-5000 mg/kg
to a pint
slightly
5-15 g/kg
to a quart
practically non-toxic
Over 15g/kg
more than 1 quart
relatively harmless
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Federal Regulatory Agencies
 Food and Drug Administration (FDA)
 Environmental Protection Agency (EPA)
 Consumer Product Safety Commission
 Department of Transportation (DOT)
 Occupational Safety and Health
Administration (OSHA)
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Symptoms of Various Types
of Poisoning
Type of Poison
Symptom/Evidence
 Caustic Poison (lye)
Characteristic burns around the lips and
mouth of the victim
Red or pink patches on the chest and thighs,
unusually bright red lividity
Black vomit
Greenish-brown vomit
Yellow vomit
Coffee brown vomit. Onion or garlic odor
Burnt almond odor
Pronounced diarrhea
Nausea and vomiting, unconsciousness,
possibly blindness
 Carbon Monoxide
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Sulfuric acid
Hydrochloric acid
Nitric acid
Phosphorous
Cyanide
Arsenic, Mercury
Methyl (wood) or
Isopropyl (rubbing) alcohol
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Critical Information
on Poisons
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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
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To Prove a Case
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Prove a crime was committed
Motive
Intent
Access to poison
Access to victim
Death was caused by poison
Death was homicidal
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Forensic Autopsy
Look for:
 Irritated tissues
 Characteristic odors
 Mees lines—single transverse white bands on nails.
Order toxicological screens
 Postmortem concentrations should be done at the
scene for comparison
 No realistic calculation of dose can be made from a
single measurement
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Human Specimens for Analysis
 Blood
 Urine
 Vitreous Humor of
Eyes
 Bile
 Gastric contents
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 Liver tissue
 Brain tissue
 Kidney tissue
 Hair/nails
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Alcohol—Ethyl Alcohol (C2H5OH)
 Most abused drug in America
 About 40% of all traffic deaths are alcohol-related
 Toxic—affecting the central nervous system, especially
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the brain
Colorless liquid, generally diluted in water
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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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
 physiology of the consumer
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BAC
Blood Alcohol Content
 Expressed as percent weight per volume of
blood
 Legal limits in all states is 0.08%
 Parameters influencing BAC:
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Body weight
Alcoholic content
Number of beverages consumed
Time between consumption
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BAC
 Burn off rate of 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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Henry’s Law
 The concentration of alcohol in breath is proportional to
that in the blood.
 This ratio of alcohol in the blood to the alcohol in the
lungs 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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Field Tests
 Preliminary tests—used to determine the degree of
suspect’s physical impairment and whether or not
another test is justified.
 Psychophysical tests—3 Basic 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 and
execute two or more simple instructions at one time.
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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 in sulfuric
acid and water
2K2Cr2O7 + 3C 2H5OH + 8H 2SO4  2Cr2(SO4)3 + 2K2SO4 + 3CH3COOH + 11 H2O
 Potassium dichromate is yellow, as concentration decreases its
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 tests reflect alcohol concentration in the pulmonary
artery.
 The 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.
 Breathalyzers now use an infrared light absorption device
with a digital read-out. Prints out a card for a permanent
record.
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