Postmortem Toxicology: Laboratory Analysis

Abstract

Abstract Postmortem toxicology is a unique application of forensic toxicology to investigate whether or not drugs or poisons contribute to the cause and manner of death. Virtually, all body parts of the deceased can be used for toxicological analysis, but the quality and availability of specimens is often affected by postmortem degradation or autolysis. An overview on the significance of different body fluids, tissues, and specimens are given. While the most common specimens of choice are blood, urine, and vitreous humor, depending on the case and availability of specimens for collection, liver, gastric content, etc. are also useful. Additional information relevant to the case, such as evidence collected at the scene, medical history, and autopsy findings, can assist in determining the appropriate toxicological analysis and to assist in the interpretation of results. Using a single analytical method for the analysis of all potential drugs and poisons with distinct chemical and physical properties is practically impossible. A typical toxicological examination usually consists of a general toxicological screening scheme and supplemented with case‐specific tests. A combination of chromatographic techniques (gas chromatography (GC) and high‐performance liquid chromatography (HPLC)) with various detection systems (nitrogen‐phosphorus, electron capture, and mass spectrometry (MS) for GC; diode‐array detector (DAD) for HPLC) are useful to provide diverse screening and analytical capabilities. Liquid‐liquid extraction and solid‐phase extraction are common extraction techniques used prior to chromatographic analysis. The application of liquid chromatography mass spectrometry (LC‐MS) has been demonstrated to be a useful complimentary technique for the analysis of those substances that are not amenable to gas chromatography mass spectrometry (GC‐MS) and high‐performance liquid chromatography diode‐array detector (HPLC‐DAD). Recent developments in the application of hybrid linear ion‐trap liquid chromatography tandem mass spectrometry (LC‐MS/MS) and LC‐time‐of‐flight‐MS have successfully demonstrated their potential use in general unknown screening. When drugs and poisons are detected, confirmation tests and, if necessary, quantitative analyses will have to be performed. To ensure the accuracy and reliability of the toxicological results, analytical methods must be properly validated.