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FORENSIC SCIENCE Toxicology

FORENSIC SCIENCE Toxicology. Toxicology. Study of poisons or the detection of foreign substances in the body that can have a toxic effect such as: Alcohol Industrial chemicals Poisonous gas Illegal drugs Drug overdoses. TOXICOLOGY. TYPES: Environmental--air, water, soil

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FORENSIC SCIENCE Toxicology

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  1. FORENSIC SCIENCEToxicology

  2. Toxicology • Study of poisons or the detection of foreign substances in the body that can have a toxic effect such as: • Alcohol • Industrial chemicals • Poisonous gas • Illegal drugs • Drug overdoses

  3. TOXICOLOGY TYPES: • Environmental--air, water, soil • Consumer--foods, cosmetics, drugs • Medical, clinical, forensic

  4. Forensic Toxicology • Postmortem--medical examiner or coroner • Criminal--motor vehicle accidents (MVA), assault, etc. • Workplace drug testing • Sports--human and animal

  5. Why do Toxicology? Toxicology can: • Be a cause of death • Contribute to death • Cause impairment • Explain behavior

  6. OUR STUDY • Drugs • Poisons • Alcohol Basically, toxicology involves the separation, detection, identification and measurement of the drug and/or poison.

  7. Drugs and Crime • Definition--a natural or synthetic substance designed to affect the subject psychologically or physiologically. • “Controlled substances”--drugs that are restricted by law • Controlled Substances Act--enacted in 1970 lists illegal drugs, their category and their penalty for possession, sale or use.

  8. Testing • PDR’s--Physician’s Desk Reference • Field Tests--presumptive tests • Lab Tests--conclusive tests

  9. PDR’s

  10. Analysis of Drugs • Controlled Substances Act • Schedule I--heroin, LSD • Schedule II--morphine, methadone • Schedule III--barbiturates, amphetamines • Schedule IV--other stimulates and depressants • Schedule V--codeine

  11. Screening tests or presumptive tests Color tests Microcrystalline test--a reagent is added that produces a crystalline precipitate which are unique for certain drugs. Confirmation tests Chromatography Spectrophotometry Mass spectrometry DRUG IDENTIFICATION

  12. Presumptive Color Tests • Marquis--turns purple in the presence of most opium derivatives and orange-brown with amphetamines • Dillie-Koppanyi--turns violet-blue in the presence of barbiturates

  13. Presumptive Color Tests • 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

  14. Confirmation TestsChromatography • Techniques for separating mixtures into their component compounds • Includes two phases--one mobile and one stationary that flow past one another • As the mixture separates it interacts with the two phases.

  15. Types of Chromatography • Paper • Thin Layer • Gas • Pyrolysis Gas • High Pressure Liquid (HPLC)

  16. Paper Chromatography • Stationary phase--paper • Mobile phase--a liquid solvent Capillary action moves the mobile phase through the stationary phase

  17. Thin Layer Chromatography • Stationary phase--a thin layer of coating on a sheet of plastic or glass (usually aluminum or silica) • Mobile phase--a liquid solvent from www.lbp.police.uk

  18. 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.

  19. Retention Factor (Rf) If the Rf value for an unknown compound is close to or the same as that for the known compound, the two compounds are most likely similar or identical (a match)

  20. Results from Thin Layer • What was in the unknown sample?

  21. Gas Chromatography • Stationary phase--a solid or very syrupy liquid lines a tube or column • Mobile phase--an inert gas like nitrogen or helium

  22. GC Analysis • Shows a peak that is proportional to the quantity of the substance present • Uses retention time instead of Rf for the quantitative analysis

  23. Retention Time • Time between the sample being injected and when it exits the column reaching the detector. • Tm is the time taken for the mobile phase to pass through the column

  24. Pyrolysis Gas Chromatography • Used when a sample does not readily dissolve in a solvent • If heating this sample decomposes it into gaseous products, these products can be analyzed by CGC

  25. A pyrogram is a visual representation of the results

  26. High Pressure LiquidChromatography • Stationary phase--fine solid particles • Mobile phase--a liquid solvent A solvent is pumped through the column as a sample is injected into it. The sample, as it moves, is slowed to differing degrees, depending on its interaction with the stationary phase. Different components of the sample mixture are, therefore, separated.

  27. Liquid Chromatography

  28. Mass Spectrometry Gas chromatography has one major drawback--it does not give a specific identification. By teaming a gas chromatograph with a mass spectrometer, this is accomplished. The mixture is separated first in a gas chromatograph. The GC column is directly attached to the mass spectrometer where a beam of electrons is shot through the sample molecules.

  29. MS (cont.) The electrons cause the molecules to lose electrons and become positively charged. These are unstable and decompose into many smaller fragments. These fragments pass through an electric or magnetic field and are separated according to their masses. NO TWO SUBSTANCES PRODUCE THE SAME FRAGMENTATION PATTERN.

  30. Example of a GS/MS

  31. Blood Urine Vitreous Bile Liver tissue Brain tissue Kidney tissue Spleen tissue Human Analysisfor Drugs

  32. “If all those buried in our cemeteries who were poisoned could raise their hands, we would probably be shocked by the numbers. --John Trestrail

  33. POISONERS in HISTORY • Olympias—a famous Greek poisoner • Locusta—personal poisoner of Emperor Nero • Lucretia Borgia—father was Pope Alexander VI • Madame Giulia Toffana—committed over 600 successful poisonings, including two Popes. • Hieronyma Spara—formed a society to teach women how to murder their husbands • Madame de Brinvilliers and Catherine Deshayes—French poisoners. AND many others through modern times.

  34. Symptoms of VariousTypes of Poisoning Type of Poison Symptom/Evidence • Caustic Poison (lye) Characteristic burns around the lips and mouth of the victim • Carbon Monoxide Red or pink patches on the chest and thighs. Unusually brighter red lividity • Sulfuric acid Black vomit • Hydrochloric acid Greenish-brown vomit • Nitric acid Yellow vomit • Phosphorous Coffee brown vomit. Onion or garlic odor • Cyanide Burnt almond odor • Arsenic, Mercury Pronounced diarrhea • Methyl (wood) or Nausea and vomiting, Isopropyl (rubbing) alcohol unconsciousness, possibly blindness

  35. Form Common color Characteristic odor Solubility Taste Common sources Lethal dose Mechanism Possible methods of administration Time interval of onset of symptoms. Symptoms resulting from an acute exposure Symptoms resulting from chronic exposure Disease states mimicked by poisoning Notes relating to the victim Specimens from victim Analytical detection methods Known toxic levels Notes pertinent to analysis of poison List of cases in which poison was used Points to Know about aPoison from “Criminal Poisoning” by John Trestrail

  36. New Terror--Yuschenko In 2004, Viktor Yushchenko announced independent candidate for president of the Ukraine. His major rival was Prime Minister Viktor Yanukovych. The campaign was often bitter, controversial, and violent, with accusations of "dirty tricks" from both sides. Yushchenko became seriously ill in early September 2004. On December 11, Austrian doctors confirmed Yushchenko was poisoned with TCDD dioxin having had more than 1,000 times the usual concentration in his body. This is the second highest dioxin level ever measured in a human. No one has ever been tried for this crime.

  37. Evidence • Class Presumptive or screening tests can be used to determine that it is a drug. • Individual Chromatography, especially in conjunction with mass spectrometry, will specifically identify a drug or poison and its components.

  38. Toxicology of Alcohol

  39. Statistics • Nearly 17,500 automobile deaths in the U.S. • 40% of all auto fatalities are due to alcohol • Over 2 million people/year injured, requiring hospitalization due to alcohol • Most abused drug; Must be able to test rapidly/accurately, due to legal needs

  40. Alcohol--Ethyl Alcohol: C2H5OH • Toxic--affecting the central nervous system, especially the brain • Toxicologists can test for alcohol in body fluids, tissues, organs • Acts as a depressant • Alcohol appears in blood within minutes of consumption; 30-90 minutes for full absorption • Detoxification--about 90% in the liver • About 5% is excreted unchanged in breath, perspiration and urine

  41. Effects of Increasing BloodAlcohol .02 MELLOW FEELING. SLIGHT BODY WARMTH. LESS INHIBITED. .05 NOTICEABLE RELAXATION. LESS ALERT. LESS SELF-FOCUSED. COORDINATION IMPAIRMENT BEGINS. .08 DRUNK DRIVING LIMIT. DEFINITE IMPAIRMENT IN COORDINATION AND JUDGMENT. .10 NOISY. POSSIBLE EMBARRASSING BEHAVIOR. MOOD SWINGS. REDUCTION IN REACTION TIME. .15 IMPAIRED BALANCE AND MOVEMENT. CLEARLY DRUNK. .30 MANY LOSE CONSCIOUSNESS .40 MOST LOSE CONSCIOUSNESS; SOME DIE. .50 BREATHING STOPS. MANY DIE.

  42. Rate of Absorption Depends on: • amount of alcohol consumed • the alcohol content of the beverage • time taken to consume it • quantity and type of food present in the stomach

  43. BACBlood Alcohol Content • Expressed as percent weight per volume • Legal limits in most states is 0.08% • Parameters influencing BAC: • Body weight • Alcoholic content • Number of beverages consumed • Time between consumption

  44. BAC • Burn off rate if 0.015% per hour but can vary • Male BAC male = 0.071 x (oz) x (% alcohol) body weight • Female BAC female = 0.085 x (oz) x (% alcohol) body weight

  45. Dose-Response Curve This is a dose-response curve for ethyl alcohol, the kind of alcohol in alcoholic beverages. At low doses the effects of alcohol are familiar and are not life-threatening, but may still be very dangerous. At higher doses, alcohol is extremely toxic to humans and can cause death.

  46. Preliminary tests--used to determine the degree of suspect’s physical impairment and whether or not another test is justified. Psychophysical tests--3 Basic Tests Horizontal gaze nystagmus (HGN)--follow a pen or small flashlight, tracking left to right with one’s eyes. In general, wavering at 45 degrees indicates 0.10 BAC. Nine Step walk and turn (WAT): comprehend and execute two or more simple instructions at one time. One-leg stand (OLS): maintain balance, comprehend andexecute two or more simple instructions at one time. Field Tests

  47. Henry’s Law • When a volatile chemical is dissolved in a liquid and is brought to equilibrium with air, there is a fixed ratio between the concentration of the volatile compound in the air and its concentration in the liquid, and this ratio is constant for a given temperature. THEREFORE, the concentration of alcohol in breath is proportional to that in the blood. • This ratio of alcohol in the blood to alcohol in the alveolar air is approximately 2100 to 1. In other words 1 ml of blood will contain nearly the same amount of alcohol as 2100 ml of breath.

  48. The Breathalyzer • more practical in the field • collects and measures alcohol content of alveolar breath • Breath sample mixes with 3 ml of 0.025 % K2Cr2O7 and 0.025 % silver nitrate in sulfuric acid and water 2K2Cr2O7 + 3C 2H5H+ 8H 2SO4  2Cr2(SO4)3 + 2K2SO4 + 3CH3COOH + 11 H2O • Potassium dichromate is yellow, as concentration decreases the light absorption diminishes so the breathalyzer indirectly measures alcohol concentration by measuring light absorption of potassium dichromate before and after the reaction with alcohol

  49. Generalizations • During absorption, the concentration of alcohol in arterial blood will be higher than in venous blood. • Breath test reflects alcohol concentration in the pulmonary artery. • Breathalyzer also can react with acetone (as found with diabetics), acetaldehyde, methanol, isopropyl alcohol, and paraldehyde, but these are toxic and their presence means the person is in serious medical condition. • Now using an infrared light absorption device with a digital read-out. Prints out a card for a permanent record.

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