Drugs & crime Testing for drugs in the lab - PowerPoint Presentation

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Drugs & crime

Testing for drugs in the lab

What are drugs?

A drug is considered to be any substance used either internally or externally as a medicine.

It can have an effect on the function or structure of living tissue through various chemical reactions

Some drugs are habit forming – these are classified as

narcotics

Types of Drugs

Over-the-Counter

: medicines that may be obtained by a consumer without a prescription from a doctor

Controlled Drugs

: a drug or medicine that is held under strict governmental control due to its strong potential for abuse or addiction. These often include

narcotics

.

Illicit Drugs

: drugs that are not legally permitted

Forensics Application

Drug identification can be instrumental in various criminal cases such as…

Deliberate Poisoning

Homicide

Accidental Death

Suicide

It is important to determine right away if a drug or poison played a role in the crime – search bodies, clothing, possessions, trash receptacles for any sign of poison/drugs.

Drugs as evidence

There must be no questions regarding drug evidence when it is presented in court.

If a substance is identified, it must be further classified as

illicit

or

over-the-counter.

Even the form of the drug may be important for sentencing in a case.

Over-the-counter

Even over-the-counter drugs can be important in forensic cases. Though they are purchased easily, they can still be dangerous – especially in cases or accidental poisoning or death.

Aspirin

Acetaminophen

Alka-Seltzer

aspirin

Acetylsalicylic Acid – synthetic pain reliever

The most widely used drug in the world

Ferric Nitrate

– an acidified solution – is used to detect aspirin. Aspirin hydrolyzes to form salicylic acid and acetic acid, and the ferric ion reacts with the salicylic acid to form a compound with a characteristic

purple color.

acetaminophen

Tylenol – non-acidic, and a good pain reliever for those allergic to aspirin.

Also reacts with ferric ions to create a characteristic color when present.

antacids

Alka-Seltzer – used to treat hyperacidity

Contain carbonates (like sodium bicarbonate – found in pop) that neutralize the acid to produce salt, water, and CO2.

Alka-Seltzer also reacts with ferric nitrate because it contains a small amount of aspirin.

Hallucinogenic drugs

Drugs that disrupt normal brain function, impairing the thought process, communication, and the ability to focus on reality.

LSD

Marijuana Alkaloids – basic nitrogen

Heroin containing plants, white powders,

Cocaine marked physiological effects

Testing for hallucinogens

Most alkaloids can be identified by the colored precipitates they form with specific reagents.

Observations under various types of light or the use of chromatography can also be useful.

**Most hallucinogenic drugs are fluorescent, so they glow under UV light. If a drug tests positive for fluorescence, it then will undergo thin-layer chromatography to further determine its makeup.

Testing for Marijuana

Marijuana is the only hallucinogen that does not contain nitrogen.

Usually, tested under a microscope for visual identification – small crystals of

calcium carbonate

found along leaf hairs and small stems.

When

hydrochloric acid

is added to marijuana, effervescence occurs (production or CO2 bubbles)

Duquenois

-Levine Test

– definitive test – when mixed with marijuana and shaken, the solution will turn

pink

, then

violet

, and then

blue

upon standing.

Heavy metal poisons

Lead and arsenic used to be the most common heavy metals used in poisoning cases. Today, we have seen an increase in heavy metal poisoning due to mercury, cadmium, and copper.

Lead – affects functioning of blood, liver, kidney, and brain. Deposited in the bones over a period of time. Even a dose of

0.5g

can be

fatal.

Mercury – concentrates in brain tissues and destroys neurons, causing blindness, convulsions, mental retardation, and even death. A dose of

1.0g

is

fatal

.

Testing for metals

Both lead and mercury damage proximal renal tubules of the kidney, resulting in a large amount of characteristic amino acids in the urine.

Paper or thin-layer chromatography tests are run with urine samples and are compared to known

Rf

values of amino acids.

Mercury

Lead

Excretion of glycine Excretion of alanine and B-

aminoisobutyric

acid