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FORENSIC SCIENCE Toxicology 1 TOXICOLOGY TYPES: • Environmental--air, water, soil • Consumer--foods, cosmetics, drugs • Medical, clinical, forensic 2 Forensic Toxicology Postmortem--medical examiner or coroner Criminal--motor vehicle accidents (MVA), assault, etc. Workplace drug testing Sports--human and animal 3 Why do Toxicology? Toxicology can: • Be a cause of death • Contribute to death • Cause impairment • Explain behavior 4 OUR STUDY Drugs Poisons Basically, toxicology involves the separation, detection, identification and measurement of the drug and/or poison. 5 Testing PDR’s--Physician’s Desk Reference Field Tests--presumptive tests Lab Tests--conclusive tests 6 PDR’s 7 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 8 DRUG IDENTIFICATION 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 9 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 10 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 11 Confirmation Tests Chromatography 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. 12 Types of Chromatography Paper Thin Layer Gas Pyrolysis Gas High Pressure Liquid (HPLC) 13 Paper Chromatography Stationary phase-paper Mobile phase--a liquid solvent Capillary action moves the mobile phase through the stationary phase 14 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 15 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. 16 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) 17 Gas Chromatography Stationary phase--a solid or very syrupy liquid lines a tube or column Mobile phase--an inert gas like nitrogen or helium 18 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 19 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 20 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 A pyrogram is the visual representation of the results 21 High Pressure Liquid Chromatography 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. 22 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. 23 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. 24 Example of a GS/MS 25 Human Analysis for Drugs Blood Liver tissue Urine Brain tissue Vitreous Kidney tissue Bile Spleen tissue 26 “If all those buried in our cemeteries who were poisoned could raise their hands, we would probably be shocked by the numbers. --John Trestrail 27 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. 28 Symptoms of Various Types of Poisoning Type of Poison • Caustic Poison (lye) • • • • • • • • Symptom/Evidence 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 Points to Know about a Poison 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 from “Criminal Poisoning” by John Trestrail 30 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. 31
