Download Forensic Toxicology

Forensic Toxicology
Forensic Toxicology
• Definition:
Controlled Substances Act
• Federal Law established 5
schedules of classification of
controlled substances based on
– Drug’s potential for abuse
– Potential to physical and
psychological dependence
– Medical Value
• Also controls materials that used in
making drugs and those that are
manufactured to resemble drugs
Drug Schedules
• Schedule I:
• Drugs with high potential for abuse and
addiction, NO medical value
Ex:
• Schedule II:
• Drugs with high potential for abuse and
addiction, have some medical value with
restrictions
Ex:
Drug Schedules
• Schedule III:
• Drugs with less potential for abuse and
addiction, currently acceptable for
medical use
Ex:
• Schedule IV:
• Drugs with low potential for abuse and
addiction, currently acceptable for
medical use
Ex:
Drug Schedules
• Schedule V:
• Drugs with low potential abuse,
medical use, lowest potential
dependency
• Ex:
Role of the Toxicologist
• Must identify one of thousands of
drugs and poisons
• Must find milligram to gram
quantities dissipated throughout the
entire body
• Not always looking for exact
chemicals, but metabolites of
desired chemicals (ex. heroin 
morphine within seconds)
Toxicology Procedures
• 10mL of
– Add
– Add
• 2 consecutive
– Some drugs take a while to show up
(1-3 days)
Toxicology Procedures
•
– color tests, TLC, GC, immunoassay
•
– GC-Mass Spec
Color Tests
• Marquis Test:
– Turns purple in the presence of Heroin,
morphine, opium
– Turns orange-brown in presence of
Amphetamines
• Scott Test: Three solutions
– Blue then pink then back to blue in the
presence of Cocaine
• Duquenois-Levine:
– Test for marijuana –turns purple
More Analytical Tests
• Microcrystalline Tests: Identifies
drug by using chemicals that reacts
to produce characteristic crystals
• Chromatography: TLC, HPLC and
gas – separate drugs/tentative ID
• Mass Spectrometry: chemical
“fingerprint” no two drugs fragment
the same
Why?
• Think of all the people that you have
“heard” do drugs.
• US drug manufacturers produce enough
barbiturates and tranquilizers each year
to give every person in the US 40 pills
• (that’s about 12 billion pills)
• 18,000 out of 44,000 annual traffic deaths
are alcohol related and send over 2
million people to the hospital
Toxicology of Alcohol
• Alcohol is absorbed through the
stomach and intestine
• Once absorbed, alcohol is:
Factors that Affect Alcohol
Absorption
Toxicology of Alcohol
• Alcohol intoxication depends on
Toxicology of Alcohol
• Alcohol 1st
affects the
forebrain
and moves
backward
• Last
affected is
medulla
oblongata
Analysis of BAC
• Field Sobriety Tests
• Breath Tests
• Blood Tests
Field Sobriety Tests
• Horizontal Gaze Nystagmus
– Involuntary eye jerk when moving horizontally
• Walk and Turn
• One-Leg Stand
Why Breath
Tests?
• The ratio
of alcohol
in blood
to
alveolar
air is
The Breathalyzer
• Invented in 1954 by
an Indiana state
trooper
• Spectrophotometer
designed to
measure the
absorption of light
passing through
potassium
dichromate
The Breathalyzer
•
2K2Cr2O7 + 3C2H5OH + 8H2SO4  2Cr2(SO4)3 + 2K2SO4 + 3CH3COOH + 11H2O
Potassium
dichromate
Ethyl
alcohol
Sulfuric
 Chromium
acid
sulfate
Potassium
sulfate
Acetic
acid
Dihydrogen
oxide
• Indirectly measures alcohol quantity by measuring amount of
potassium dichromate
Infrared and Fuel Cell
Breath Tests
• Infrared Breath Test
uses infrared
wavelengths to test for
acetone or other
interferences in the
breath
• Fuel Cell Test
converts fuel
(alcohol) and
oxygen into a
measurable electric
current
Alcohol
and the Law
• 1939-1964:
intoxicated =
• 1965: intoxicated =
• 2003: intoxicated =
Alcohol and the Law
• Try the drink wheel:
http://www.intox.com/wheel/drinkwheel.asp
The End