Post Mortem Forensic Toxicology

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Post Mortem Forensic Toxicology

• Jeffery Hackett
• MSc PhD CSci CChem MRSC
• jhackett_at_unitedchem.com

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What is it?

• Post-Mortem Forensic Toxicology determines the
  absence or presence of drugs and their
  metabolites, chemicals such as ethanol and other
  volatile substances, carbon monoxide and other
  gases, metals, and other toxic chemicals in human
  fluids and tissues, and evaluates their role as a
  determinant or contributory factor in the cause
  and manner of death

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Where do I find out about it?

• Journals
• Forensic Science International
• J.Forensic Science
• J. Anal. Toxicology
• J.Chromatogr. B (and A)
• Books
• R.C. Baselt Disposition of Toxic Drugs and
  Chemicals in Man
• Clarkes Analysis of Drugs and Poisons
• J.Garriot Medico-legal Aspects of Alcohol

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Interesting cases

• Dr. Crippen Hyocine
• Georgi Markov Ricin
• Justin Devilliers Fentanyl
• Ivan Litvanenko Polonium
• Mrs Cahill Cyanide
• Stacy Castor Ethylene Glycol

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Whats it all really about

• 1. How drugs get into people
• 2. How we get the drugs out
• 3. How drugs are tested for
• 4. What does it all mean??

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1. How do drugs get into people??

• Intoxicants Ethanol (Other Alcohols)
• Oral administration
• Butane (Other gases)
• Toluene(also Solvents)
• Via Inhalation
• Marilyn Monroe?

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Illicit Drugs

• Cannabinoids Smoked
• Amphetamines Oral
• Cocaine/ Heroin Smoked, Snorted, Injected

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Prescription Drugs

• Acetaminophen
• Propoxyphene
• Fentanyl
• Oxycodone
• Zolpidem
• Temazepam
• Methadone
• Mainly oral administration, some have been
  abused in other ways

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Weird and Wonderful
Mephedrone MCat
Spice (JWH-018)
Salvia Divinorum
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Route of DrugsOral administration

• A.D.M.E.
• Drugs will leave from the stomach
• Pass through the Liver
• Enter into Blood stream/ CSF
• Leave through Liver/Kidneys
• Pass into Urine

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What does this mean for sampling?

• Blood is always important (Site?)
• Liver will sequester higher levels of
  drugs
• Lungs are excellent for solvents
• Urine is the last point for drugs
• Hair has problems all of its own
• Vitreous Humor Alcohol Data
• Brain?? Oral Fluid

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THC in Blood (LC-MSMS)1 ng per mL
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2. Getting the drugs out

• Volatile/Semivolatile Headspace
• Acid drugs Solvent extraction
• Basic drugs Solid phase (micro) extraction
• Metals/Metalloids Digestion

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Headspace Analysis

• Samples are warmed to create an atmosphere
• Aliquots are taken of the vapour
• This is free of contamination/ interferences
• Low boilingPropane
• Medium Ethanol
• High Toluene

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Solvent extraction

• pH Modification
• Addition of acid/ base
• COOH ??COO- H
• H R-COO-? COOH
• Neutral Species are more soluble in
  organic solvents

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Solid phase extraction

• Samples are pH modified
• Filtered through porous sorbents
• Drugs are collected onto modified surfaces
• Interferences are washed off
• Compounds of interest are eluted off
• pH pKa 2
• pHpKa log ionised/unionised

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Digestion

• Dry digestion
• Samples are heated, ignited and ashed
• Residue is dissolved in dilute acid
• Good for Copper, Lead, Zinc etc
• Wet digestion
• Samples are heated in strong acid solution
• Solution is reduced in volume, neutralized and
  diluted
• Good for volatile metals Mercury
• Thallium

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Drug Testing

• Immunoassay
• ELISA/EMIT/FPIA/RIA
• Chromatography
• Gas Chromatography (FID, ECD, MS)
• Liquid Chromatography (PDA, FLD, MS/MS)

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ELISA Instrumentation
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Method

• Immunoassays are Presumptive Tests
• All operators are competency trained.
• Calibrators are matrix matched
• Set at Negative, Cut off and Positive
  values
• Good for Blood, Urine and Tissue
• Wide range of analytes available

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ELISA Analysis
 
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Gas-ChromatographyInstrumentation
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Example of Gas-Chromatography
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Gas-Chromatography Mass Spectrometry
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Mass Spectrometry
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Liquid ChromatographyInstrumentation
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Example of Liquid Chromatography (xanthines
Theophylline/ Theobrmine/ Caffeine/
8-Chlorotheophylline)
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Different Detectors (LC)UV and Fluorescence
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LC-MSMS
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Chromatographic Methods

• Use Validated/Peer Reviewed ones
• Internal Standards (IS) must match analytes
• Best IS are deuterated (MS)
• Substituted Analogues (FID,NPD)
• Non-drug materials
• extraction involves Volatile Solvents (GC)
• Miscible Solvents (LC)

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Chromatographic Analysis

• Involves
• Calibration curves with known
  standards and controls
• Derivitization with recognized
  modifiers (BSTFA, PFPA)
• Recognized detection methods
• (SIM, MRM, PDA)

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Calibration CurveTHC and Metabolite
THC (0.25 to 50 ng/ mL)
Carboxy-THC (0.25 to 50 ng/ mL)
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4. What does it all mean Toxicology Report
RESULTS   Blood (Iliac)   Ethyl Alcohol Not
Detected5 Benzoylecgonine 0.05 mg/L1,2,4
Sertraline 0.11 mg/L2,4 Desmethylsertraline
0.01 mg/L2,4 Quetiapine 0.50 mg/L   Negative
for Acetaminophen, Amitriptyline, Barbiturates,
Chlordiazepoxide, Citalopram, Clomipramine,
Cocaethylene, Cocaine, Desipramine, Diazepam,
Doxylamine, Ibuprofen, Imipramine, Meperidine,
Methadone, Methamphetamine, N-desmethyltramadol,
Norpropoxyphene, Pentazocine, Phenytoin,
Procainamide, Procaine, Strychnine,
Thioridazine, Tramadol, Trazodone,
Trimipramine, Venlafaxine, and Verapamil.2,4 Fo
r example use onlyNot a real report.
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Interpretation of Drugs
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Psilocybin/ Psilocin Question
PB IS PC
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Interpretation of AlcoholClinical Values

• BAC/g Effect
• 0.02 Relaxed
• 0.05 Tranquil
• 0.10 Coordination problems
  0.20 Intoxication Obvious
• 0.30 Passing Out
• 0.40 Comatose
• 0.50 Death

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Post Mortem AlcoholA Point of View

• Widmark
• BAC 100 A
• WtWf
• Back-Extrapolation
• Post Absorptive Period
• Linear Elimination
• No Alcohol Consumption
• Should not be applied because of the number
  variables

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New Issue (EtG/ EtS)
Ethylglucuronide molecule
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My Thanks

• Albert Elian
• Bob Osiwiecz (Erie Co. Med Examiner Lab)
• J. Spencer
• Mike Telepchak