Forensic toxicology

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The forensic toxicology is a field between chemistry and medicine and supports using toxicological , pharmaceutical and chemical methods to investigate unnatural deaths, poisonings and drug and substance abuse. Samples are taken either from the tissue of organs or from the body fluids urine , blood or saliva . Forensic toxicology in the sense of judicial poisoning theory makes a significant contribution to the clarification of criminal and civil law issues.

history

The doctrine of poison aroused interest from the 17th century when poisonous murders were committed on a large scale in various countries, mainly with arsenic . At that time, however, there were still no detection methods to convict the perpetrators. It was not until the beginning of the 19th century that Mathieu Orfila laid the foundations for the new subject. James Marsh , who developed the Marsh probe in 1836 , made an important contribution to the detection of arsenic poisoning . At that time, most poisonings were still carried out using arsenic. Today, however, arsenic poisoning is extremely rare. In 1850, Jean Servais Stas developed a method for separating nicotine from a poison victim by means of ether extraction. This process, further developed by Julius Otto in 1856, is still used today as the Stas Otto process for the extraction of alkaloids from body tissues. Poisons were identified with appropriate detection reagents until the 1950s. After that, the rapid development of instrumental analysis made the identification of toxic substances from body fluids and tissue samples much easier .

Substances and modern detection methods

Frequently analyzed substances are drugs , medicines , insecticides , solvents and other chemical compounds that can act as poison , the following examples of which are amenable to forensic toxicological investigation:

The substances from body tissues are enriched by liquid-liquid extraction with suitable solvents.

The analysis methods are thin-layer chromatography , spectroscopic methods such as IR spectroscopy or UV spectroscopy (to identify the pure substance) and gas chromatography-mass spectrometry or HPLC-MS (for reliable identification in substance mixtures). Gas chromatography (GC) and high-performance liquid chromatography (HPLC) are also used for larger amounts of substance . In addition, immunochemical tests ( antigen-antibody reactions ) are playing an increasingly important role.

evaluation

The examination results are assessed taking into account the following questions:

  • Are the chemical detection methods qualitatively and quantitatively meaningful?
  • Is there a suspicion of intentional poisoning, abuse or an accident?
  • Which pathological - anatomical changes can be determined, e.g. B. Chemical burns , type of dead spots , appearance of organs?
  • Which criminal investigations can contribute to the assessment or indicate the direction of a possible further investigation?

literature

Web links

Society for Toxicology and Forensic Chemistry

Remarks

  1. ↑ Jürgen Thorwald: Traces in the dust or stages of forensic chemistry and biology. In: Jürgen Thorwald: The hour of the detectives. Becomes and worlds of criminology. Droemer Knaur, Zurich and Munich 1966, p. 286 ff.
  2. ↑ Schönberg L, Grobosch T, Lampe D, Kloft C: Toxicological screening in urine: comparison of two automated HPLC screening systems, toxicological identification system (TOX.IS *) versus REMEDI-HS. , J Anal Toxicol. 2007 Jul-Aug; 31 (6): 321-7, PMID 17725877