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 useEx:

• Schedule IV: • Drugs with low potential for abuse and

addiction, currently acceptable for medical useEx:

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

• Indirectly measures alcohol quantity by measuring amount of potassium dichromate

Potassium dichromate

Ethyl alcohol

Sulfuric acid

Chromium sulfate

Potassium sulfate

Acetic acid

Dihydrogen oxide

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