Transcript Document

Forensic Science:
An Introduction
Drugs and Toxicology
Dependence
Drug – natural or synthetic substance used
to produce a physiological or psychological
effect.
 Psychological dependence – emotional
attachment to the drug
 Physical dependence – physiological need
characterized by withdrawal sickness if not
taken
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Narcotics
Depresses vital body functions
 Physical – yes
 Psychological – high
 Opiates - Morphine,Heroine,Codeine
 Synthetic Opiates - Methadone,OxyContin
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Hallucinogens
Induces changes in normal though and
moods
 Physical – no
 Physiological – only PCP
 Marijuana ( THC), Hashish
 LSD
 PCP
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Depressants
Slows down functions of the CNS
 Physical - yes
 Psychological – varies
 Alcohol
 Barbituates (Quaaludes)
 Antipsychotics/anxiety (Valium)
 Huffing materials
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Stimulants
Speeds up the CNS
 Physical – only nicotine
 Psychological – varies
 Amphetamines – speed
 Methamphetamines (crsytal meth)
 Cocaine/crack
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Others
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Club Drugs
GHB, Rohybinol (Roofies) - depressants
 Ecstacy, ketamine – stimulants/hallucogens
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Anabolic Steroids
Controlled Substance Act
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Schedule I – no current medical use; heroin,
marijuana, methaqualone, LDS
Schedule II – current medical use; high
dependence; opiates not in Sch I, cocaine,
methadone, PCP, most amphetamines, most
barbituates
Schedule III – less potential for abuse, current
medical use; low-mod phys abuse; codeine,
anabolic steroids, barbs not Sch II
Schedule IV – low potential for abuse;
tranquilizers, Valium,
Schedule V – low abuse and dependence; opiate
drug mixtures with nonnarcotic medicinal
ingredients
Drug Analysis
Screening – preliminary test used to reduce
the number of possible identities of unknown
substances
 Confirmation – a single test that specifically
identifies a substance
 Qualitative – determines the identity of the
substance
 Quantitative – determines the amount of the
substance
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Color Tests
Marquis – heroine, morphine, opiates
(amphetamines, methamphetamines
Dillie-Koppanyi – barbiturates
 Duquenois-Levine – marijuana
 Van Urk – LSD
 Scott Test – cocaine
 Microcrystalline Tests – a chemical test
that creates crystals when added to the
drug. The size and color identifies the
substance.
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Chromatography
Molecules in a mobile phase are attracted to
a stationary phase and are thus separated
out of a mixture.
 TLC – stationary phase is a gel-coated plate
 GC –mobile gas phase moves over a
stationary liquid phase in a column
 Uses retention time to identify substances
and has the sensitivity to detect at a
nanogram level.
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Spectrophotometry
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Identifying a substance by the way it absorbs
selected wavelengths of light
Absorption spectrum
Beer’s Law
UV spec – establishes a probable identity by
eliminating others
IR spec – complex enough for specific
identification
Mass spec – paired with GC; provide fingerprint via
fragmentation patterns of a substance
Toxicology
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Toxicology – the detection and identity of drugs and
poisons in the body fluids, tissues and organs
 Absorption – passage across the wall of the stomach
and small intestine into the blood stream
 Distribution – where the substance travels and has its
effect once in the blood
 Metabolism – the alteration of a substance into other
chemicals in the body in order to eliminate it
 Elimination – how the body gets rid of the substance
and/or its metabolites
 Toxicity – the impact the drug or poison has on the
body
Alcohol
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Absorbed quickly into all watery portions in the
body
BAC is affected by time of consumption, type,
food in stomach, etc
Eliminated by oxidation (into CO2 and water) or
excretion (breath, urine)
BAC determined by analyzing blood or breath
Henry’s Law - 2100:1 ratio of alcohol in the
blood to alcohol in alveolar air( 1 ml of blood has
as much alcohol as 2100 ml of alveolar air)
Blood is collected with anticoagulant and a
preservative
Police In the Field
Field sobriety testing – psychophysical tests
 Horizontal-gaze nystagmus – eye jerking on
a side to side movement
 Walk and turn and one-leg stand tests are
divided attention tasks
 Breathalyzer
 Legal BAC – less than 0.08% or DWI/DUI
 Implied consent
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Toxicologist
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Must detect very small amounts of a drug that most
likely has been metabolized and then determine its
toxicity
Specimens collected by medical examiner or
physician
Blood (1-10 ml)
Urine (1-2 voids)
Hair (long-term use)
Cocaine, alcohol, and marijuana make up 90% of
the drugs encountered in a tox lab
Techniques
Acid-base extraction – allows extraction and
categorization of some drugs
 Screening tests – TLC, GC, immunoassay
 Confirmation tests – GC/MS
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Non-drug poisons
Heavy metals – As, Bi, At, Hg, Th
 Screen with Reinsch test – X + HCl + Co
 Confirm – emission spec or X-ray diffraction
 CO – suicide or murder, percent saturation
of CO in blood, outcompetes O2 in blood
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Toxicologist must assess
drug’s influence on the behavior of the
individual
 determine past history with drug
 possible drug interactions
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