Forensic Toxicologist identifies and analyzes poisons, drugs, and chemicals studies the effect of such substances on the body Important in helping medical examiner determine cause of death in an autopsy all the blood and tissue samples undergo a toxicology screening.
Toxicology Tests: Chromatography – separate and quantify individual chemical compounds Mobile phase – substance is dissolved in solvent Stationary phase – dissolved substance is passed through a finely divided adsorbent, different compounds move at different speeds, rates of adsorption are plotted on a chart.
Toxicology Tests: Thin-Layer Chromatography (TLC) – uses a glass or plastic plate covered with a thin layer of finely ground adsorbent such as silica gel or alumina sample is deposited on the plate locations of separated components are noted after the solvent evaporates
Toxicology Tests: Gas Chromatography – separates liquids and gases material is coated on fine clay or glass beads and packed into a steel or copper column column is heated above boiling point of liquid gas pushes compounds through column detectors measure emerging fractions
Toxicology Tests:Mass Spectrometry – identifies the chemical structure of an unknown substance after separating a substance using gas chromatography each component enters a vacuum chamber the components collide with a beam of high-energy electrons causing the component molecules to lose electrons and become charged ions they then pass through a magnetic or electric field where they are separated according to their masses and can be identified
Toxicology Tests:Spectrophotometry - measures how much radiation from the electromagnetic spectrum is absorbed by a particular chemical
At the Crime Scene Crime scene technicians can Fire accelerants conduct field tests Blood that detect many Explosives chemical residues Gunshot residue found at crime Drugs scenes, in Cosmetic material vehicles, or on Construction material clothing Trace metals
Types of chemical evidence Solids – poisons, drugs, soil, cement, minerals, explo sive residues, gunshot residues, cosmetics, trace materials Liquids – acids, gasoline, body fluids, beverages, chemicals for drug labs, cleaning fluids, medications, poisons Gases – natural gases, refrigerants, butane, propane, tear gas, propellants