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Forensic toxicology

Forensic toxicology. Part I – Drugs of Abuse. Drug vs. Poison. A drug is a natural or synthetic substance designed to affect humans (or other animals) psychologically and/or physically. A drug taken in excess, showing its toxic effects, causing illness or death is considered a poison .

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Forensic toxicology

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  1. Forensic toxicology Part I – Drugs of Abuse

  2. Drug vs. Poison • A drugis a natural or synthetic substance designed to affect humans (or other animals) psychologically and/or physically. • A drug taken in excess, showing its toxic effects, causing illness or death is considered a poison. Dramamine Overdose: Drowsiness, Seizures, Convulsions, Difficulty Breathing, DEATH

  3. Controlled and Illicit Substances • Controlled Substances are drugs or chemicals whose manufacture, possession and use are regulated by the government. • Illegal Drugs (Drug Enforcement Agency) • Prescription Drugs (Federal Drug Administration) • Over the Counter Drugs (OTC) • Illicit Substances (aka drugs of abuse) are drugs taken strictly for pleasure whether produced legally or illegally. • Designer Drugs – drugs produced solely for abuse and evasion of specific drug laws.

  4. Drugs Crimes and Use Statistics • Direct drug crimes consist of the possession, manufacturing, and distribution of illicit substances. • Indirect drug crimes are those that are committed to support a person’s drug addiction or are crimes that are committed while someone is under the influence of drugs.

  5. Drug Classification According to Pharmacology (4 Types) • Pharmacology - The science of drugs, including their composition, uses, and effects • 1. Hallucinogens (psychedellic drugs) • Changes normal thought processes, perceptions and moods • Desired Effects Include: • Hallucinations (visual or auditory) • Super strength in some cases • Undesirable Side Effects • Amnesia • Depression • Anxiety • Psychosis

  6. Drug Classification (continued) • 2. Stimulants (Uppers) • Act on the central nervous system to increase energy and/or alertness while suppressing appetite and fatigue. • Desired Effects Include: • Mental alertness • Increased energy • Undesirable Side Effects • Restlessness • Anxiety • Sudden Death

  7. Drug Classification (continued) • 3. Narcotics (analgesics) • Act on pain centers in the central nervous system • Synthetic narcotics are known as opiates • Desired Effects Include: • Pain relief • Anxiety relief • Undesirable Side Effects • Death • Serum hepatitis

  8. Drug Classification (continued) • 4. Depressants (Downers) • sometimes referred to as sedatives and tranquilizers, are substances that can slow brain activity. • Desired Effects Include: • Anxiety relief • Relaxation • Undesirable Side Effects • Depression • Chronic Fatigue • Anxiety

  9. DEA Schedules of Controlled Substances • Schedule I Controlled Substances • Substances in this schedule have no currently accepted medical use in the United States, a lack of accepted safety for use under medical supervision, and a high potential for abuse. • Some examples of substances listed in Schedule I are: heroin, LSD, marijuana, methaqualone, and ecstasy.

  10. DEA Schedules of Controlled Substances • Schedule II Controlled Substances • Substances in this schedule have a high potential for abuse which may lead to severe psychological or physical dependence. • Examples of Schedule II narcotics include: methadone, oxycodone, Percocet, morphine, and opium. • Example of Schedule II stimulants include: methamphetamine

  11. DEA Schedules of Controlled Substances • Schedule III Controlled Substances • Substances in this schedule have a potential for abuse less than substances in Schedules I or II and abuse may lead to moderate or low physical dependence or high psychological dependence. • Examples of Schedule III narcotics include: Vicodin and Codeine • Examples of Schedule III non-narcotics include: ketamine, and anabolic steroids.

  12. DEA Schedules of Controlled Substances • Schedule IV Controlled Substances • Substances in this schedule have a low potential for abuse relative to substances in Schedule III. Examples: Valium, Xanax, Halcion. • Schedule V Controlled Substances • Substances in this schedule have a low potential for abuse relative to substances listed in Schedule IV and consist primarily of preparations containing limited quantities of certain narcotics. Example: some OTC cough medicines

  13. Basic Laboratory Science • Standard/reference samples allow the laboratory to establish the known properties of a material so that the identity of crime scene evidence can be determined. • Positive test – A test result that indicates the substance being tested for is present in the sample. • False positive test – A test result that indicates that the substance being tested for is present when it is not. • Negative test – A test result that indicates that the substance being tested for in a sample is absent or in too small a quantity to be detected.

  14. Basic Laboratory Science • Qualitative test – A test that determines that a substance is present. • Quantitative test – A test that determines how much of a substance is present

  15. Screening tests vs. Confirmatory Tests • Screening test- a test that is nonspecific and preliminary in nature. • May test for a class of substances • Example: Class: Opiates Drugs: heroin, morphine, codeine • Often can be performed in the field – field test • Confirmatory test- a single test that specifically identifies a substance

  16. Principles of Drug Analysis • Criminal penalties depend on the actual substance present in a sample and the amount of substance present. • Drug analysis process • Step 1: Chemist performs screening tests • Visual/microscopic • Microcrystalline • Spot test – In the field • Thin-layer chromatography (TLC) – in the lab • Step 2: Chemist performs a quantitative analysis to confirm the sample’s identity and determine its mass • Infrared spectroscopy (IR) • Gas Chromatography and mass spectroscopy (GC/Mass Spec)

  17. The Spot Test • Samples are mixed with chemicals to determine if drugs are present • A positive test results in a color change. • Standards are always tested along with samples

  18. Thin-layer Chromatography (TLC) • A Separation technique that takes advantage of the solubility and physical properties of the controlled substance to separate and distinguish compounds in a mixture • Has solid stationary phase (silica gel plate) and liquid moving phase (solvent). • If the sample to be analyzed is solid, it must first be dissolved in a suitable solvent.

  19. Identifying Drugs by TLC • Procedure: • A small amount of drug sample is applied to a TLC plate. • Standards are always tested with samples. • The plate is placed in a solvent. • After a period of time, the plate is removed and visualized. • Plates can either be placed under ultraviolet light revealing those materials that fluoresce as bright spots on dark background. • Or, the plate can be sprayed with a chemical reagent that reacts with the separated substances and causes them to form colored spots.

  20. Identifying Drugs by TLC • Analysis of a TLC plate • Rf is a calculated ratio of the distance moved by a drug relative to the distance moved by the solvent used in developing the plate.

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