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Forensic Toxicology Testing

Forensic Toxicology Testing. Forensic Toxicology. Definition: The science of detecting and identifying the presence of drugs and poisons in body fluids, tissues, and organs. Role of the Toxicologist. Must identify one of thousands of drugs and poisons

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Forensic Toxicology Testing

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  1. Forensic Toxicology Testing

  2. Forensic Toxicology • Definition: • The science of detecting and identifying the presence of drugs and poisons in body fluids, tissues, and organs.

  3. Role of the Toxicologist • Must identify one of thousands of drugs and poisons • Must find nanogram to microgram quantities dissipated throughout the entire body • Not always looking for exact chemicals, but metabolites of desired chemicals (ex. heroin breaks down into morphine within seconds)

  4. Obtaining specimens • Antemortem samples • 10mL of whole blood • Urine • Postmortem samples • Hair (collect metabolites) • Vitreous humor • Liver • Stomach contents • Larvae

  5. Color Tests • Marquis Test: • Turns purple in the presence of Heroin, morphine, opium • Turns orange-brown in presence of Amphetamines • Scott Test:Three solutions • Blue then pink then back to blue in the presence of Cocaine • Duquenois-Levine: • Test for marijuana –turns purple

  6. Marquis’ Reagent • 2% formaldehyde in sulfuric acid • Turns purple in presence of heroine & morphine • Turns orange-brown in presence of amphetamines & methamphetamines

  7. Dillie-Koppanyi • Screening test for barbiturates • Positive test turns violet-blue color

  8. Duquenois-Levine Test • Valuable color test for presence of marijuana • Set of 3 solutions that are added in succession to suspected sample • Turns a purplish color in chloroform layer.

  9. Van Urk test • Positive test for presence of LSD • Sample turns blue-purple color • Aka – Ehrlich’s Reagent.

  10. Scott test • Color test for presence of cocaine • Turns blue in solution A • Addition of solution B, turns pink • Addition of solution C bottom layer turns blue

  11. More Analytical Tests • Microcrystalline Tests • Chromatography • Spectrophotometry • Mass Spectrophotometry

  12. Urinalysis • Color of urine (clear and pale to deep yellow) is due to urochrome which is a pigment that results when hemoglobin is broken down • Some drugs and vitamins may alter urine color. Cloudy urine is indicative of a urinary infection.

  13. Urine pH • Usually slightly acidic (pH 6). • Body metabolism and diet can cause urine pH to vary from 4.5 to 8. • Large amounts of protein and whole wheat cause acidic urine • Vegan diets or bacterial infections can cause pH to climb and become alkaline (>7)

  14. Urine Specific Gravity • SG is the ratio of the density of substance divided by the density of water. • SG of water is 1.0, urine is 1.001-1.035

  15. Abnormal components in urine • Glucose – condition is called Glycosuria. Caused by diabetes mellitus or high intake of sugars • Proteins – Proteinuria or Albuminuria. Caused by pregnancy, high protein diets, heart failure, severe hypertension, renal disease. • Hemoglobin – Hemoglobinuria. Caused by transfusion reaction or severe burns • Erythrocytes – Hematuria. Cause by bleeding in urinary tract (kidney stones). • Leukocytes – Pyuria. Caused by urinary tract infection.

  16. Benedict’s Test for Glucose • Glucose is a reducing sugar- this means it has a free aldehyde group • CuSO4 Cu++ + SO4-- • 2 Cu++ + Reducing Sugar Cu+        (electron donor) • Cu+ Cu2O (ppt) • The final color of the solution depends on how much of this precipitate is formed and therefore the color gives an indication of how much reducing sugar was present. • Increasing amounts of reducing sugar • green orange red brown

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