Transcript Slide 1

Drugs
Drugs
Objectives
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, overthe-counter medications, and illegal
drugs.
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Drugs
Objectives, continued
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.
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Drugs
Objectives, continued
You will be able to:
Describe IR, UV-VIS spectroscopy, and GCMS.
Present and interpret data with graphs.
Use the Physicians’ Desk Reference (PDR)
to identify pills.
Use technology and mathematics to improve
investigations and communications.
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Drugs
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.
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Drugs
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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Drugs
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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Drugs
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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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.
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Human Components Used for Drug Analysis
Blood
Liver tissue
Urine
Brain tissue
Hair
Kidney tissue
Gastric contents
Spleen tissue
Bile
Vitreous humor of the eye
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Drugs
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.
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Drugs
Drug Identification
Screening or presumptive tests
Confirmatory tests
Spot or color tests
Spectrophotometry
Microcrystalline test—
• Ultraviolet (UV)
a reagent is added, producing a
crystalline precipitate that is unique for
a certain drug
• Visible
• Infrared (IR)
Mass spectrometry
Chromatography
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Drug Identification, continued
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.)
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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
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Drugs
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
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Types of Chromatography
Paper
Thin-layer (TLC)
Gas (GC)
Pyrolysis gas (PGC)
Liquid (LC)
High-performance liquid (HPLC)
Column
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Paper Chromatography
Stationary 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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Drugs
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
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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.)
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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 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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Drugs
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.
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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.
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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 difficult to identify in both techniques.
Both are compared to a catalog of knowns.
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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.
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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.
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