Drugs

Drugs

2

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

Drugs

3

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

Drugs

4

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

Drugs

5

Drugs and Crime

A 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.

Drugs

6

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

Drugs

7

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

Drugs

8

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

Drugs

9

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.

Drugs

10

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

Drugs

11

Physicians’ Desk Reference

PDR—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.

Drugs

12

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

Drugs

13

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

Drugs

14

Presumptive Color Tests

Marquis—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

Drugs

15

Chromatography

A 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

Drugs

16

Types of Chromatography

Paper

Thin-layer (TLC)

Gas (GC)

Pyrolysis gas (PGC)

Liquid (LC)

High-performance liquid (HPLC)

Column

Drugs

17

Paper Chromatography

Stationary phase—paper

Mobile phase—a liquid solvent

Capillary action moves the mobile

phase through the stationary phase.

Drugs

18

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

Drugs

19

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).

Retention Factor (Rf)

Drugs

20

Gas Chromatography

Phases

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

Mobile—an inert gas like

nitrogen or helium

Analysis

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

Uses retention time instead of Rf for the qualitative analysis

Drugs

21

Uses of Gas Chromatography

Not 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.)

Drugs

22

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

Drugs

23

Spectrophotometry

Components

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

Drugs

24

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

Drugs

25

Mass Spectrometry

Gas 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.

Drugs

26

Mass Spectrometry, continued

In 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.

Drugs

27

Mass Spectra

Each molecular species has its own unique mass spectrum.

Drugs

28

IR Spectrophotometry and Mass Spectrometry

Both work well in identifying pure substances.

Mixtures are difficult to identify in both techniques.

Both are compared to a catalog of knowns.

Drugs

29

People of Historical Significance

Arthur 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.

Drugs

30

People of Historical Significance, continued

Francis 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.