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Forensic Science: An Introduction

Forensic Science: An Introduction. Drugs and Toxicology. Dependence. Drug – natural or synthetic substance used to produce a physiological or psychological effect. Psychological dependence – emotional attachment to the drug

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Forensic Science: An Introduction

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  1. Forensic Science: An Introduction Drugs and Toxicology

  2. Dependence • Drug – natural or synthetic substance used to produce a physiological or psychological effect. • Psychological dependence – emotional attachment to the drug • Physical dependence – physiological need characterized by withdrawal sickness if not taken

  3. Narcotics • Depresses vital body functions • Physical – yes • Psychological – high • Opiates - Morphine,Heroine,Codeine • Synthetic Opiates - Methadone,OxyContin

  4. Hallucinogens • Induces changes in normal though and moods • Physical – no • Physiological – only PCP • Marijuana ( THC), Hashish • LSD • PCP

  5. Depressants • Slows down functions of the CNS • Physical - yes • Psychological – varies • Alcohol • Barbituates (Quaaludes) • Antipsychotics/anxiety (Valium) • Huffing materials

  6. Stimulants • Speeds up the CNS • Physical – only nicotine • Psychological – varies • Amphetamines – speed • Methamphetamines (crsytal meth) • Cocaine/crack

  7. Others • Club Drugs • GHB, Rohybinol (Roofies) - depressants • Ecstacy, ketamine – stimulants/hallucogens • Anabolic Steroids

  8. Controlled Substance Act • Schedule I – no current medical use; heroin, marijuana, methaqualone, LDS • Schedule II – current medical use; high dependence; opiates not in Sch I, cocaine, methadone, PCP, most amphetamines, most barbituates • Schedule III – less potential for abuse, current medical use; low-mod phys abuse; codeine, anabolic steroids, barbs not Sch II • Schedule IV – low potential for abuse; tranquilizers, Valium, • Schedule V – low abuse and dependence; opiate drug mixtures with nonnarcotic medicinal ingredients

  9. Drug Analysis • Screening – preliminary test used to reduce the number of possible identities of unknown substances • Confirmation – a single test that specifically identifies a substance • Qualitative – determines the identity of the substance • Quantitative – determines the amount of the substance

  10. Color Tests • Marquis – heroine, morphine, opiates (amphetamines, methamphetamines Dillie-Koppanyi – barbiturates • Duquenois-Levine – marijuana • Van Urk – LSD • Scott Test – cocaine • Microcrystalline Tests – a chemical test that creates crystals when added to the drug. The size and color identifies the substance.

  11. Chromatography • Molecules in a mobile phase are attracted to a stationary phase and are thus separated out of a mixture. • TLC – stationary phase is a gel-coated plate • GC –mobile gas phase moves over a stationary liquid phase in a column • Uses retention time to identify substances and has the sensitivity to detect at a nanogram level.

  12. Spectrophotometry • Identifying a substance by the way it absorbs selected wavelengths of light • Absorption spectrum • Beer’s Law • UV spec – establishes a probable identity by eliminating others • IR spec – complex enough for specific identification • Mass spec – paired with GC; provide fingerprint via fragmentation patterns of a substance

  13. Toxicology • Toxicology – the detection and identity of drugs and poisons in the body fluids, tissues and organs • Absorption – passage across the wall of the stomach and small intestine into the blood stream • Distribution – where the substance travels and has its effect once in the blood • Metabolism – the alteration of a substance into other chemicals in the body in order to eliminate it • Elimination – how the body gets rid of the substance and/or its metabolites • Toxicity – the impact the drug or poison has on the body

  14. Alcohol • Absorbed quickly into all watery portions in the body • BAC is affected by time of consumption, type, food in stomach, etc • Eliminated by oxidation (into CO2 and water) or excretion (breath, urine) • BAC determined by analyzing blood or breath • Henry’s Law - 2100:1 ratio of alcohol in the blood to alcohol in alveolar air( 1 ml of blood has as much alcohol as 2100 ml of alveolar air) • Blood is collected with anticoagulant and a preservative

  15. Police In the Field • Field sobriety testing – psychophysical tests • Horizontal-gaze nystagmus – eye jerking on a side to side movement • Walk and turn and one-leg stand tests are divided attention tasks • Breathalyzer • Legal BAC – less than 0.08% or DWI/DUI • Implied consent

  16. Toxicologist • Must detect very small amounts of a drug that most likely has been metabolized and then determine its toxicity • Specimens collected by medical examiner or physician • Blood (1-10 ml) • Urine (1-2 voids) • Hair (long-term use) • Cocaine, alcohol, and marijuana make up 90% of the drugs encountered in a tox lab

  17. Techniques • Acid-base extraction – allows extraction and categorization of some drugs • Screening tests – TLC, GC, immunoassay • Confirmation tests – GC/MS

  18. Non-drug poisons • Heavy metals – As, Bi, At, Hg, Th • Screen with Reinsch test – X + HCl + Co • Confirm – emission spec or X-ray diffraction • CO – suicide or murder, percent saturation of CO in blood, outcompetes O2 in blood

  19. Toxicologist must assess • drug’s influence on the behavior of the individual • determine past history with drug • possible drug interactions

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