ch7--drugs by pptfiles

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									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 Dr. G Tools of the trade

Drugs
 A drug is a natural or synthetic substance designed to affect the subject psychologically or physiologically.  Can effect the function or structure of living tissue through various chemical reactions.  Some drugs are habit forming and are classified as narcotics (regulated by Federal law)
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Drugs/Poisons
Whenever a drug is taken in excessive amounts and causes illness or death, exhibits toxic properties, it is classified as a poison.

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Drugs and Crime
 “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
 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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At the crime scene
If a victim is found unconscious, must determine if a drug or poison was administered to the victim and what the substance was. The crime scene needs to be carefully searched for evidence…it is easier to determine what poisoned a victim by examining container than to have to examine the victim’s body parts.
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Identification of Drugs
 PDR—Physicians’ Desk Reference  Field Tests—presumptive tests

 Laboratory Tests—conclusive tests

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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

Confirmatory tests
 Spectrophotometry  Ultraviolet (UV)  Visible  Infrared (IR)  Mass spectrometry

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Human Components Used for Drug Analysis
 Blood
 Urine  Hair

 Liver tissue
 Brain tissue  Kidney tissue

 Gastric Contents
 Bile

 Spleen tissue
 Vitreous Humor of the Eye

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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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Heavy Metal Poisoning
Mercury
• Concentrates in the brain tissues and can cause blindness, convulsions, mental retardation, even death • Fatal dose 1 gram • Mercury poisons producing glycine in the urine • Found in batteries, thermometers,industrial waste, contaminated fish, electrical equipment
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Lead
• Affects the functioning of blood, liver, kidney and brain • Deposited in the bones over time • Fatal dose 0.5 g • Lead poisoning produces alanine in the urine • Found in storage batteries, industrial paint, solder, ceramic glazes, solder, leaded gas, paint pigments
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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) Colum
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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 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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