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Forensic Toxicology Midterm 117
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Forensic Toxicology - ANSWER application of science + study of poisons to elucidation of questions that
occur in judicial proceedings
principles of forensic toxicology - ANSWER - to attempt to provide answers to questions that may arise
during criminal investigations/ in subsequent court proceedings
Carl Wilhelm Scheele - ANSWER German Chemist
converted arsenic trioxide to arsine gas using nitric acid in presence of zinc
James Marsh - ANSWER English Chemist
who developed "Marsh Test" (arsenic mirror) to detect this poison in biological specimens
Matthew J. B. Orfila - ANSWER "Father of Toxicology" 1813
chemist must aim to perfect process necessary for establishing case of poisoning in order to reveal crime
+ to assist magistrate to punish the guilty
questions that must be answered - ANSWER has this person been poisoned?
what is the identity of the poison?
how was it administered?
what are its effects?
was it dangerous/ lethal amount?
Forensic toxicology chemical analyses - ANSWER detect presence of poison
measure its concentration
relate this to its known toxicity/ effects on organism
,Forensic Toxicology Midterm 117
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forensic toxicologist situations - ANSWER toxicological investigations
human + animal performance testing
forensic drug testing
toxicological investigations - ANSWER - to establish poisoning as COD
- to investigate unlawful poisoning by 3rd party; in cases of non-accidental child poisoning; in cases of
drug-facilitated sexual assault
- to establish presence of substance that may affect a person's behavior/ ability to make
rational/reasoned judgment
human + animal performance testing - ANSWER - to investigate incidents of driving under the influence
of drugs +/ alcohol
- to detect use of performance-enhancing drugs in human + animal sports
forensic drug testing - ANSWER - to detect non-compliance w/ policies governing use of drugs in
workplace
- to provide evidence in case where parents may be denied access to young children on basis of history
of drug abuse + where continued abuse may endanger child
Poisons - ANSWER Group 1: gases
Group 2: volatile substances
Group 3: drugs
Group 4: metals
Group 5: pesticides
Group 6: anions
Group 7: miscellaneous substances
classifications of poisons - ANSWER classified according to method used for extraction:
, Forensic Toxicology Midterm 117
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- gaseous + volatile substances isolated by distillation/, by sampling headspace above sample help in
closed container
- organic non-volatile substances isolated by solvent extraction ( drugs + pesticides)
- metallic poisons isolated by ashing, by wet oxidation of organic matter/ by enzymatic hydrolysis of
tissue
- toxic anions isolated by dialysis
- miscellaneous poisons that require immunoassays/ special extraction techniques, such as ion-exchange
columns, formations of derivatives/ ion-pairs, freeze-drying + continuous extraction w/ polar solvent
Analytical System - ANSWER to exclude/ indicate presence of any poison in each of chemical groups
Importance of Documentation - ANSWER Secure chain of custody:
- aspect of sampling
- avoidance of contamination
- appropriate packaging of samples
- chain of custody + recording sample info @ all stages of process
- type of body fluids + other samples
- aim of analysis + individual case circumstances
Most analyses require several unit operations: - ANSWER - separation of poison + its metabolites from
biological material
- concentration
- identification
-confirmation of identity
- quantification
typically 4 main steps in any toxicological examination - ANSWER 1. detection
2. identification
3. quantification