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Forensic Toxicology

Notes Outline
by

Diane Tucker

on 14 December 2012

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Transcript of Forensic Toxicology

Notes Outline Forensic Toxicology A disinfectant must be applied because...

to negate any argument that an alcoholic disinfectant may have inadvertently contributed to a falsely high blood-alcohol result

The type of container that best ensures the preservation of blood samples is...

an airtight container

Two substances that should be added to a blood sample after collection are...

(1) An anticoagulant to prevent clotting and (2) a preservative to inhibit the growth of microorganisms capable of destroying alcohol

Storage temperature affects alcohol's stability in blood by...

failure to keep the blood refrigerated or to add a preservative may result in a decline in alcohol concentration.

The presence of a preservative affects alcohol's stability in blood by...

Longer storage times may also reduce alcohol concentration It is best, when collecting postmortem blood samples for alcohol determination to collect a number of blood samples from different body sites because...

alcohol may be generated in a deceased individual as a result of bacterial action.

The blood-alcohol concentration that is the current legal measure of drunk driving in the United States, as established by the National Highway Traffic Safety Administration is...

0.08 percent weight/volume, or 0.08 grams of alcohol per 100 milliliters of blood

A per se law is...

any individual meeting or exceeding a defined blood-alcohol level (usually 0.08 percent) shall be deemed intoxicated, and no other proof of alcohol impairment is necessary An implied-consent law is...

the operator of a motor vehicle on a public highway must either consent to a test for alcohol intoxication, if requested, or lose his or her license for some designated period - usually six months to one year

Two challenges toxicologists face in detecting drugs and determining their toxicity are:

(1) not dealing with drugs at the concentration levels found in powders and pills

(2) few substances enter and completely leave the body in the same chemical state

Bodily fluids that should be collected from any suspected drug user are...

blood and urine Three drugs that account for 90% or more of the drugs encountered in a typical toxicology laboratory are:

(1) alcohol

(2) marijuana

(3) cocaine

The first task of a forensic toxicologist when establishing an analytical scheme to detect and identify drugs is...

to remove and isolate drugs and other toxic agents from the biological materials submitted as evidence

Acids... a compound capable of donating a hydrogen ion to another compound. Bases...

A compound capable of accepting a hydrogen ion.

Acids and bases are used to extract and categorize drugs by...

They are used to categorize drugs by how acidic or basic a water solution is in which blood, urine, or tissues are dissolved. Acid drugs are easily extracted from an acidified water solution with organic solvents, while basic drugs are readily removed from a basic water solution with organic solvents. The difference between a screening test and a confirmation test is...

a screening test gives quick insight into the likelihood that a specimen contains a drug substance. It allows a toxicologist to examine a large number of specimens within a short period of time for a wide range of drugs. A confirmation test identifies a specific drug or drugs.

The three screening tests most widely used by forensic toxicologists are:
(1) thin-layer chromatography (TLC)
(2) gas chromatography (GC)
(3) Immunoassay
The confirmation test of choice is...

Gas chromatography/mass spectrometry

Out of the following: lead arsenic, mercury, thallium; which is not classified as a heavy metal?

Lead

Inhaling carbon monoxide can cause death by...

because it combines with hemoglobin, reducing the amount of hemoglobin left to carry oxygen. If enough hemoglobin combines with carbon monoxide, not enough is left to carry suffiecint oxygen to the tissues, and death by asphyxiation follows.

Factors in addition to blood centration levels that must be considered before drawing conclusions about a subject's drug-induced behavior are:

(1) age
(2) physical condition
(3) the tolerance of the drug user
(4) the additive or synergistic effects caused by the interaction of two or more drugs

The concentration of a drug present in urine is a poor indicator of how extensively an individual's behavior or state is influenced by the drug because...

urine is formed outside the body's circulatory system, and consequently drug levels can build up in it over a relatively long period of time A toxicologist is...

an individual whose job is to detect and identify drugs and poisons in body fluids, tissues, and organs.

Three settings in which a toxicologist often works are:
(1) crime lab
(2) medical examiners' office
(3) hospital labs
(4) various health facilities The most widely abused drug in Western countries is...

alcohol

Metabolism - the transformation of a chemical in the body to other chemicals to facilitate its elimination from the body.

The three stages of alcohol's fate in the human body are:
(1) absorption
(2) distribution
(3) elimination Alcohol accumulates in these parts of the body...

the watery parts of the body

Factors that influence the rate at which alcohol is absorbed into the bloodstream are:
(1) total time taken to consume the drink
(2) the alcohol content of the beverage
(3) the amount consumed
(4) the quantity and type of food present in the stomach at the time of drinking
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