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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 effects.

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 affect 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 ActSchedule 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, continuedSchedule 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 IIIExamples: stimulants and depressants including Valium, Xanax, Librium, phenobarbital, Darvon

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Controlled Substances Act, continuedSchedule 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 AnalysisBlood

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 IdentificationScreening 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 and orange-brown with amphetamines

Dille-Koppanyi—turns violet-blue in the presence of barbiturates

Duquenois-Levine—turns a purple color in the presence of marijuana

Van Urk—turns a blue-purple in the presence 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 in a particular solvent.

It is determined by measuring the distance the compound traveled and dividing it by the distance the solvent traveled.

If the Rf value for an unknown compound is close to or the same as that for the known compound, the two compounds are likely similar or identical (a match).

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Gas ChromatographyPhases

Stationary—a solid or a viscous liquid that lines a tube or column

Mobile—an inert gas like nitrogen or helium

AnalysisShows a peak that is proportional to the quantity of the substance present

Uses retention time instead of Rf

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 affect guilt or innocence.)

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Confirmatory Tests: SpectroscopySpectroscopy—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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SpectrophotometryComponents

A radiation source

A frequency selector

A sample holder

A detector to convert electromagnetic radiation into an electrical signal

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 the electromagnetic spectrum

Compares the IR light beam before and after it passes through a 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 SpectrometryBoth work well in identifying pure substances.

Mixtures are difficult to identify in both techniques.

Both are compared to a catalog of knowns.

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People of Historical SignificanceArthur Jeffrey 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.