Transcript ppt chapter 7

Chapter 7
Drugs
“Having sniffed the dead man’s lips, I
detected a slightly sour smell, and I
came to the conclusion that he had
poison forced upon him.”
—Sherlock Holmes, in Sir Arthur Conan Doyle’s
A Study in Scarlet
Drugs
Students will learn:
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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.
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Drugs
Students will be able to:
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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
 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.
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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
 Controlled Substances Act is a law that
was enacted in 1970; it lists illegal drugs,
their category and their penalty for
possession, sale or use.
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Controlled Substances Act
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Schedule I—high potential for abuse; no currently acceptable
medical use in the US; a lack of accepted safety for use under
medical supervision
Schedule II—high potential for abuse; a currently accepted
medical use with severe restrictions; abuse may lead to severe
psychological or physical dependence
Schedule III—lower potential for abuse than the drugs in I or II; a
currently accepted medical use in the US; abuse may lead to
moderate physical dependence or high psychological dependence
Schedule IV—low potential for abuse relative to drugs in III; a
currently accepted medical use in the US; abuse may lead to
limited physical or psychological dependence relative to drugs in III
Schedule V—low potential for abuse relative to drugs in IV;
currently accepted medical use in the US; abuse may lead to
limited physical or psychological dependence relative to drugs in IV
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Examples of Controlled
Substances and Their Schedule
Placement
 Schedule I—heroin (diacetylmorphine), LSD,
marijuana, ecstasy (MDMA)
 Schedule II—cocaine, morphine, amphetamines
(including methamphetamines), PCP, Ritalin
 Schedule III—intermediate acting barbiturates,
anabolic steroids, ketamine
 Schedule IV—other stimulants and depressants
including Valium, Xanan, Librium, phenobarbital,
Darvon
 Schedule V—codeine found in low doses in cough
medicines
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Identification of Drugs
 PDR—Physicians’ Desk Reference
 Field Tests—presumptive tests
 Laboratory Tests—conclusive
tests
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Human Components
Used for Drug Analysis
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 Blood
 Liver tissue
 Urine
 Brain tissue
 Hair
 Kidney tissue
 Gastric Contents
 Spleen tissue
 Bile
 Vitreous Humor of
the Eye
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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, whether it
is a prescription, over the counter, or a
controlled substance; as well as more
detailed information about the drug.
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Drug Identification
Screening or
presumptive tests
 Spot or color tests
 Microcrystalline test—
a reagent is added
that produces a
crystalline precipitate
which is unique for a
certain drug.
 Chromatography
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Confirmatory tests
 Spectrophotometry
 Ultraviolet (UV)
 Visible
 Infrared (IR)
 Mass spectrometry
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Presumptive Color Tests
 Marquis—turns purple in the
presence of most opium
derivatives and orange-brown
with amphetamines
 Dillie-Koppanyi—turns violetblue 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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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
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Paper
Thin Layer (TLC)
Gas (GC)
Pyrolysis Gas (PGC)
Liquid (LC)
High Pressure 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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Gas Chromatography
Phases
 Stationary—a solid or a
viscous liquid that lines a
tube or column
 Mobile—an inert gas like
nitrogen or helium
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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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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 Spectometry
 Material absorbs energy in the near-IR region of the
electromagnetic spectrum.
 Compares the IR light beam before and after passing
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 Spectrometry
Gas chromatography has one major drawback;
it does not give a specific identification. Mass
spectrometry cannot separate mixtures. By
combining the two (GCMS), constituents of
mixtures can be specifically identified.
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Mass Spectrometry
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 a 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
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
developed, 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
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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