Postmortem Toxicology: Artifacts

Abstract

This article attempts to highlight important artifacts (misleading signs) being an inherent part of postmortem toxicology. A major issue with specimens collected for a postmortem toxicology investigation is an understanding of drug use in the antemortem setting as well as the medical history. Drug concentration is likely to change already during perimortem. The potential for postmortem redistribution largely depends on the drug's physicochemical/pharmacokinetic properties and environmental conditions, and can be dependent on the site and time. Body fluids and tissues as well as drugs are affected by autolysis (cell disruption) and putrefaction. Degradation as well as formation of new entities occurs as competing processes to postmortem redistribution. Analysis of formalin‐treated samples may create problems with regard to sample processing along with the loss, decomposition, or methylation of drugs. The main collection artifact is contamination. Poor sampling will severely affect a case investigation, as well as the use of inappropriate specimen containers and preservatives. Precaution taken to preserve drug stability during storage until analysis is guided by current knowledge. Problems may also occur during the isolation and identification of a drug. A thoroughly evaluated determination of the parent drug along with major metabolites/degradation products seems necessary to avoid misinterpretation.

Issues Affecting Interpretation: Stability and Artefacts

“…Stability data for drugs in postmortem specimens have recently been reviewed (Skopp 2004(Skopp , 2009Drummer 2008Drummer , 2010. Possible mechanisms operating on drugs during the postmortem interval are given in Table 49.3.…”

“…An accumulation of methylecgonine has been observed if fluoride is present; acidification and storage at 4°C of blood decreases the formation of benzoylecgonine from cocaine. Acidification may not only stabilise cocaine but also N-glycosides (Skopp 2009). Sodium fluoride has been suggested to prevent formation of ethanol in postmortem blood; nevertheless, in vitro formation of ethanol has been observed in samples containing fluoride (Hoiseth et al 2008).…”

“…Trichloroacetic acid is a metabolite of the solvent trichloroethylene or of chloral hydrate with an elimination half-life of 3-5 days. Further valuable information on artefacts is covered by a few reviews (Skopp 2009;Drummer 2010;Baselt 2011).…”

“…Artificial formation of a compound or instability of an analyte can occur at any stage of the bioanalytical process including collection, processing, storage, extraction and analysis resulting in an over-or underestimation of the drug; in some cases, the particular drug may even escape detection (Li et al 2010). In addition, in a postmortem toxicology investigation such changes may have already occurred during the process of dying, pretreatment of the corpse and the postmortem time period (Skopp 2004(Skopp , 2009.…”