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You will understand:

How to apply deductive reasoning

to a series of analytical data.

The limitations of presumptive

(screening) tests.

The relationship between the

electromagnetic spectrum and

spectroscopic analysis.

The dangers of using prescription

drugs, controlled substances,

over-the-counter medications,

and illegal drugs.

Objectives

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You will be able to:

Chemically identify illicit drug types.

Classify the types of illicit drugs and

their negative e ects.

Discuss the federal penalties for

possession and use of controlled

substances.

Explain the need for confirmatory

tests.

Objectives, continued

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You will be able to:

Describe IR, UV-VIS spectroscopy, and

GC-MS.

Present and interpret data with graphs.

Use the Physicians’ Desk Reference(PDR) to identify pills.

Use technology and mathematics to

improve investigations and

communications.

Objectives, continued

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Drugs and CrimeA drug is a natural or synthetic substance designed to a ect the

subject psychologically or physiologically.

“Controlled substances” are drugs that are restricted by law.

The Controlled Substances Act is a law that was enacted in 1970;

it lists illegal drugs, their categories, and penalties for

possession, sale, or use.

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Controlled Substances Act

Schedule I—high potential for abuse; no currently accepted

medical use in the U.S.; a lack of accepted safety for use under

medical supervision

Examples: heroin (diacetylmorphine), LSD, marijuana, ecstasy

(MDMA)

Schedule II—high potential for abuse; a currently

accepted medical use with severe restrictions; abuse

may lead to severe psychological or physical

dependence

Examples: cocaine, morphine, amphetamines (including

methamphetamines), PCP, Ritalin

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Controlled Substances Act, continued

Schedule III—lower potential for abuse than the drugs in I or II;

a currently accepted medical use in the U.S.; abuse may lead to

moderate physical dependence or high psychological

dependence

Examples: intermediate-acting barbiturates, anabolic steroids,

ketamine

Schedule IV—low potential for abuse relative to drugs in III; a currently accepted medical use in the U.S.; abuse may lead to limited physical or psychological dependence relative to drugs in III

Examples: stimulants and depressants including Valium, Xanax, Librium, phenobarbital, Darvon

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Controlled Substances Act, continued

Schedule V—low potential for abuse relative to drugs in IV;

currently accepted medical use in the U.S.; abuse may lead to

limited physical or psychological dependence relative to drugs

in IV

Examples: codeine found in low doses in cough medicines

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Illegal or Illicit?

An illegal drug is a drug that is against the law to have, use,

or distribute.

An illicit drug is a legal drug used in an inappropriate or

illegal way.

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Human Components Used for Drug Analysis

Blood

Urine

Hair

Gastric contents

Bile

Liver tissue

Brain tissue

Kidney tissue

Spleen tissue

Vitreous humor of the

eye

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Physicians’ Desk ReferencePDR—A Physicians’ Desk Reference is used to identify

manufactured pills, tablets, and capsules. It is updated each

year. This can sometimes be a quick and easy identifier of the

legally made drugs that may be found at a scene. The

reference book gives a picture of the drug and states whether

it is prescription, over-the-counter, or a controlled substance;

it gives more detailed information about the drug as well.

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Drug Identification

Screening or presumptive tests

Spot or color tests

Microcrystalline test—

a reagent is added, producing a

crystalline precipitate that is

unique for a certain drug

Chromatography

Confirmatory tests

Spectrophotometry

• Ultraviolet (UV)

• Visible

• Infrared (IR)

Mass spectrometry

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Screening or presumptive tests only tell that the drug is possibly

present.

Confirmatory tests tell that the drug is positively present.

(Screening tests are easier, cheaper, and quicker to use.)

Drug Identification, continued

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Presumptive Color TestsMarquis—turns purple in the presence

of most opium derivatives andorange-brown with amphetamines

Dille-Koppanyi—turns violet-blue inthe presence of barbiturates

Duquenois-Levine—turns a purplecolor in the presence of marijuana

Van Urk—turns a blue-purple in thepresence of LSD

Scott test—color test for cocaine; blue

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ChromatographyA technique for separating mixtures into their components

Includes two phases—a mobile one that flows past a stationary one

The mixture interacts with the stationary phase and separates

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Types of ChromatographyPaper

Thin-layer (TLC)

Gas (GC)

Pyrolysis gas (PGC)

Liquid (LC)

High-performance liquid (HPLC)

Column

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Paper ChromatographyStationary phase—paper

Mobile phase—a liquid solvent

Capillary action moves the mobile

phase through the stationary

phase.

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Thin-layer Chromatography

Stationary phase—a thin layer

of coating (usually alumina

or silica) on a sheet of plastic

or glass

Mobile phase—a liquid solvent

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Retention Factor (Rf)This is a number that represents

how far a compound travels ina particular solvent.

It is determined by measuring thedistance the compoundtraveled and dividing it by thedistance the solvent traveled.

If the Rf value for an unknowncompound is close to or thesame as that for the knowncompound, the two compoundsare likely similar or identical (amatch).

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Gas Chromatography

Phases

Stationary—a solid or aviscous liquid that lines a tubeor column

Mobile—an inert gas like

nitrogen or helium

Analysis

Shows a peak that is proportional to the quantity ofthe substance present

Uses retention time instead ofRf for the qualitative analysis

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Uses of Gas ChromatographyNot considered a confirmation of a controlled substance

Used as a separation tool for mass spectroscopy (MS) and

infrared spectroscopy (IR)

Used to quantitatively measure the concentration of a sample.

(In a courtroom, there is no real requirement to know the

concentration of a substance. It does not a ect guilt or

innocence.)

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Confirmatory Tests: Spectroscopy

Spectroscopy—the interaction of electromagnetic radiation

with matter

Spectrophotometer—an instrument used to measure and

record the absorption spectrum of a chemical substance

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Spectrophotometry

Components

A radiation source

A frequency selector

A sample holder

A detector to convert electromagnetic radiation into an electricalsignal

A recorder to produce a record of the signal

Types

Ultraviolet

Visible

Infrared

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Infrared Spectrometry

Material absorbs energy in the near-IR region of theelectromagnetic spectrum

Compares the IR light beam before and after it passes througha transparent sample

Result—an absorption or transmittance spectrum

Gives a unique view of the substance; like a fingerprint

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Mass SpectrometryGas chromatography has one major drawback: It does not give

a specific identification. Mass spectrometry cannot separate

mixtures. By combining the two (GC-MS), constituents of

mixtures can be specifically identified.

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Mass Spectrometry, continuedIn a mass spectrometer, an electron beam is directed at sample

molecules in a vacuum chamber. The electrons break apart the

sample molecules into many positive-charged fragments. These

are sorted and collected according to their mass-to-charge

ratio by an oscillating electric or magnetic field.

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Mass Spectra

Each molecular species has its own unique mass spectrum.

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IR Spectrophotometry and Mass Spectrometry

Both work well in identifying pure substances.

Mixtures are di cult to identify in both techniques.

Both are compared to a catalog of knowns.

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People of Historical Significance

Arthur Je rey Dempster was born in Canada, but studied at and

received his PhD from the University of Chicago. He began

teaching physics there in 1916. In 1918, Dempster developed

the first modern mass spectrometer. His version was over 100

times more accurate than previous ones and established the

basic theory and design of mass spectrometers that is still used

to this day.

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People of Historical Significance, continuedFrancis William Aston was a British physicist who won the

1922 Nobel Prize in Chemistry for his work in the invention

of the mass spectrograph. He used a method of

electromagnetic focusing to separate substances. This

enabled him to identify no fewer than 212 of the 287

naturally occurring elemental isotopes.