CHEM 107 - Ch. 13 - Forensic Toxicology

Field sobriety tests

Tests used by law enforcement officers to estimate a motorist's degree of physical impairment by alcohol and determine whether an evidential test for alcohol is justified.

Gas chromatography

The most widely used approach for determining blood-alcohol levels in a forensic laboratory.

Screening test

Provides the analyst with quick insight into the likelihood that a specimen contains a drug substance.

Drug recognition expert program

Uses standardized methods to examine automobile drivers who are suspected of being under the influence of drugs.

What do toxicologists do?

Detect and identify the presence of drugs and poisons in body fluids, tissues, and organs.

How long does it take for alcohol to enter the bloodstream once ingested?

A couple minutes.

Alcohol absorption

Alcohol slowly increases in concentration while it is being absorbed from the stomach and the small intestine into the bloodstream.

When does the post absorption period begin?

When all the alcohol has been absorbed and a maximum alcohol level is reached in the blood.

What happens during post absorption?

The alcohol concentration slowly decreases until a zero level is reached.

How is elimination of alcohol in the body accomplished?

Through oxidation and excretion.

Where is alcohol excreted from?

Breath, urine, and perspiration.

Where does oxidation take place?

Primarily in the liver.

How do breath testers measure blood-alcohol concentration?

By measuring the degree of the interaction of the light with alcohol in the captured breath sample.

On what principle do breath-testing devices operate?

That the ratio between the concentration of alcohol in deep-lung or alveolar breath and its concentration in blood is fixed.

What are some examples of field sobriety tests?

Walk and turn and the one leg stand test.

What is the goal of the forensic toxicologist?

Devise an analytical scheme to detect, isolate, and specifically identify toxic drug substances extracted from biological fluids, tissues, and organs.

What happens when a screening test comes back positive?

The results are considered tentative until further confirmation tests ensue.

What are the most widely used screening tests?

Thin-layer chromatography, gas chromatography, immunoassay.

What is accepted as the confirmation test of choice?

Gas chromatography/mass spectrometry.

What happens once a drug is identified in a confirmation test?

A toxicologist may be required to determine the drug's effect on an individual's natural performance or physical state.

What reliable data is required to prove drug intoxication?

Reliable data from a forensic toxicologist.