Chapter 7

Drugs

Chapter 7 - Drugs (and Crime)

A drug is a natural or synthetic substance designed to affect the subject psychologically or physiologically.

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.

“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.

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

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

Controlled Substances Act, continuedSchedule 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

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

Narcotics: analgesics, relieve pain by depressing central nervous system activity; leads to physical dependence;

opium derivatives, such as morphine, heroin

Hallucinogens: Cause marked changes in thought processes, perceptions, and mood

Includes marijuana, LSD, PCP, MDMA

Depressants:

Alcohol, barbiturates, tranquilizers, inhalants

Stimulants:

Amphetamines, cocaine, crack

Classes of drugs

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.

Human Components Used for Drug AnalysisBlood

Urine

Hair

Gastric contents

Bile

Liver tissue

Brain tissue

Kidney tissue

Spleen tissue

Vitreous humor of the eye

Drug evidence can be collected in the form of:

®Powders

®Tablets

®Capsules

®Vegetable matter

®Liquids

®Pipes

®Cigarettes

®Cookers

®syringes

They contain active drug ingredients as well as inactive substances or additives (sugar, starch, quinine) to increase quantity, dilute potency, and raise total value.

Drug Identification

Screening or presumptive tests

Spot or color tests

Microcrystalline test—

a reagent is added to sample on a microscopic slide, producing a crystalline precipitate that is unique for a certain drug; size and shape of crystals are specific to drug type

Chromatography

Confirmatory tests

Spectrophotometry

• Ultraviolet (UV)

• Visible

• Infrared (IR)

Mass spectrometry

Screening or presumptive tests only tell that the drug is possibly present. (Screening tests are easier, cheaper, and quicker to use.)

Confirmatory tests tell that the drug is positively present.

2-step procedure:

1) Use screening tests to reduce the number of possibilities to a small and manageable number.

2) Use more sophisticated tests to pinpoint and confirm the identity of the drug.

Presumptive Color Tests(not conclusive evidence – not allowed in court)

Marquis — 2% formaldehyde in sulfuric acid; turns purple in the presence of most opium derivatives and orange-brown with amphetamines/methamphetamine

Dille-Koppanyi — 1% cobalt acetate in methanol followed by 5% isopropylamine in methanol; turns violet-blue in the presence of barbiturates

Duquenois-Levine — Solution A 2% vanillin and 1% acetylaldehyde in ethyl alcohol; Solution B concentrated HCl and Solution C (chloroform); a purple color in the chloroform layer indicates the presence of marijuana

Van Urk — turns a blue-purple in the presence of LSD

Scott test — color test for cocaine; Solution A turns blue; Solution B will turn the blue color to clear pink then Solution C will make the blue color reappear

ChromatographyA technique for separating mixtures into their individual components

Requires a comparison between known and unknown drugs so one must have a tentative ID on drug type before analysis.

Complements the color and crystal tests.

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

The mixture interacts with the stationary phase and separates

Types of Chromatography

Paper Thin-layer (TLC)

Gas (GC) Pyrolysis gas (PGC)

Liquid (LC)

High-performance liquid (HPLC) Column

Paper ChromatographyStationary phase—paper

Mobile phase—a liquid solvent

Capillary action moves the mobile phase through

the stationary phase.

Thin-layer ChromatographyStationary phase—a thin layer of coating (usually alumina

or silica) on a sheet of plastic or glass

Mobile phase—a liquid solvent

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).

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

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.)

Confirmatory Tests: SpectroscopySpectroscopy—the interaction of

electromagnetic radiation with matter

Spectrophotometer—an instrument used to measure and record the absorption of light in the ultraviolet (UV) and infrared (IR) regions of the electromagnetic (EM) spectrum of a chemical substance

Components Types

A radiation source Ultraviolet, Visible, Infrared

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

Additional notesUV range is not conclusive. It only establishes a probable identity

for the substance.IR can specifically identify a substance, like a fingerprint

Infrared SpectrometryMaterial 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

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.

In a mass spectrometer, a high-energy electron beam is directed at sample molecules in a vacuum chamber. The electrons break apart the sample molecules into many positive-charged fragments. No two compounds fragment in the exactly the same way. These are sorted and collected according to their mass-to-charge ratio by an oscillating electric or magnetic field.

Mass Spectra

Each molecular species has its own unique mass spectrum.

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.

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.

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.