Toxicology The Study of Poisons

Alcohol Testing Blood – 10-20 mL of blood should be obtained (officer must be careful NOT to use alcohol to clean the syringe or the area of skin from which the sample is drawn). Urine – Subject should first void the bladder, then provide a 25-mL sample after 20 minutes Breath – Tested in the field (breathalyzer)

Samples (blood or urine) are generally tested by gas chromatography (GC) Small sample is injected into GC and is immediately vaporized. A carrier gas (nitrogen or helium) moves sample through tube (column). Constitiuents of mixture (blood or urine) exit the column at different times. A peak on the GC chart shows the presence and level of alcohol in the sample.

Drugs Sample is separated into acidic (barbiturates, aspirin) and basic (amphetamines, cocaine, methadone, PCP) “fractions.” Thin-Layer Chromatography or Gas Chromatography is performed Immunoassay – specific antigen-antibody reactions (like blood typing) GCMS is preferred

Poisons in Death Investigations Samples are collected: 3 ounces of blood (no preservatives) – taken from both chambers of heart All stomach contents (sometimes stomach itself) ½ of the liver Both kidneys All urine from bladder ½ of the brain (entire brain if volatile poison is suspected) Both lungs if volatile poison is suspected Spleen if cyanide is suspected

Circumstances that May Point to Poison If body is skeletonized: hair, nails, bones Medicines or other substances found near victim Cups, glasses, and other containers Circumstances that May Point to Poison Corrosion or burns about the mouth Presence of drugs or paraphernalia Victim being a “burden” on others – makes him/her a target