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 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, 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, marijuana, 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, continued 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 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 Classes of drugs 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 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 Analysis Blood Liver tissue Urine Brain tissue Hair Kidney tissue Gastric contents Spleen tissue Bile 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 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. 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. Screening or presumptive tests Confirmatory tests Spot or color tests Spectrophotometry Microcrystalline test— • Ultraviolet (UV) 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 • Visible • Infrared (IR) Mass spectrometry 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 Chromatography A 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 Chromatography Stationary phase—paper Mobile phase—a liquid solvent Capillary action moves the mobile phase through the stationary phase. 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 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 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 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.) Confirmatory Tests: Spectroscopy Spectroscopy—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 notes UV range is not conclusive. It only establishes a probable identity for the substance. IR can specifically identify a substance, like a fingerprint 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 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. 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 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. 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.