MAY 1, 2013

EQ: How can toxins be collected and identified?

WARM-UP:Read the Case Study: Death by Tylenol on pg223 (Blue book)/ pg 234 (Orange book) and answer the following questions:

1. How many people died as a result of ingesting what they thought to be was Tylenol?

2. What substance were they actually taking?3. How was the poison distributed?4. What is this known as?5. Has/have the perpetrator(s) been found? What is the

reward?

TOXICOLOGY

BLOOD ALCOHOL LAWS:*In 1992, the U.S. Dept. of Transportation (DOT) recommended that states adopt 0.08 % BAC as the legal measure of drunk driving.

*One is 4 times more likely to be involved in an automobile accident at the 0.08 level.

TECHNIQUES USED IN

TOXICOLOGY:

FORENSIC TOXICOLOGISTS:*The first step in analyzing drugs is a color test.

*Many drugs yield characteristic colors when brought into contact with specific chemicals.

*Useful for screening purposes only

FORENSIC TOXICOLOGISTS:*Toxicologists have a very difficult job to do. They have to narrow down thousands of possibilities to one

*Post mortem blood tends to produce ethyl alcohol from bacterial action, therefore sometimes the collection of urine and vitreous humor (liquid in eye) is collected.

BLOOD ALCOHOL:*Alcohol is ingested through the mouth, down the esophagus, to the stomach where 20% of it is absorbed through the portal veins.

*The rest of the alcohol is absorbed by the small intestines and carried to the liver, and moves up to the heart which distributes it to all your tissues.

THIN LAYER CHROMATOGRAPHY (TLC):

Uses a solid stationary phase and a moving liquid to separate the parts of a mixture.

GAS CHROMATOGRAPHY/MASS SPECTOMETRY:

*Separates mixtures based on their distribution between a stationary liquid phase and a moving gas phase.

*After the mixture is separated it passes through a high-vacuum chamber, that passes a beam of high-energy electrons causing fragments to be separated according to their masses.

INFRARED LIGHT/FUEL CELL DETECTORS:

A fuel cell converts energy from a chemical reaction into electrochemical energy.

Any alcohol present in the subjects breath flows into the chamber and a beam of infrared light passes through the chamber.

SCREENING & CONFIRMATION TESTS:

Three most widely used screening tests:1. TLC2. GC3. Immunoassay-best for detecting the low drug levels associated with marijuana

Toxicologists follow up positive screening test with a confirmation test; GC/mass spectometry

DETECTING DRUGS (Heavy Metals):

Environmental protection regulations restrict their availability to the general public.

DETECTING DRUGS:*Hair is nourished by blood flowing through capillaries located close to the hair root.

*Hair grows at a rate of _____ per month, therefore it can be used to date drugs used over a period of weeks, months or years depending of the hair’s length.

1 cm

DETECTING DRUGS:*Carbon Monoxide (CO) is one of the most common poisons found in a forensic lab.

*It is a common way that some individuals commit suicide.

*When the amount of CO in the blood reaches 50-60% saturation, the results can be fatal.