Postmortem metabolomics: strategies to assess time-dependent postmortem changes of Diazepam, Nordiazepam, Morphine, Codeine, Mirtazapine and Citalopram

Postmortem redistribution (PMR) can result in artificial drug concentration changes following death and complicate forensic case interpretation. Currently, no accurate methods for PMR prediction exist. Hence, alternative strategies were developed investigating the time-dependent postmortem behavior of diazepam, nordiazepam, morphine, codeine, mirtazapine and citalopram. For 477 authentic postmortem cases, femoral blood samples were collected at two postmortem time-points. All samples were quantified for drugs of abuse (targeted; liquid chromatography-tandem mass spectrometry LC-MS/MS) and characterized for small endogenous molecules (untargeted; gas chromatography-high resolution MS (GC-HRMS). Trends for significant time-dependent concentration decreases (diazepam (n = 137), nordiazepam (n = 126)), increases (mirtazapine (n = 55), citalopram (n = 50)) or minimal median postmortem changes (morphine (n = 122), codeine (n = 92)) could be observed. Robust mathematical mixed effect models were created for the generalized postmortem behavior of diazepam and nordiazepam, which could be used to back-calculate drug concentrations towards a time-point closer to the estimated time of death (caution: inter-individual variability). Significant correlations between time-dependent concentration changes of morphine, mirtazapine and citalopram with individual endogenous molecules could be determined; no correlation was deemed strong enough for successful a posteriori estimation on the occurrence of PMR for specific cases. The current dataset did successfully lead to a significant knowledge gain in further understanding the time-dependent postmortem behavior of the studied drugs (of abuse)

The effectiveness of decontamination procedures used in forensic hair analysis

Hair is a mainstream specimen used in forensic toxicology to determine drug use and exposure. However, the interpretation of an analytical hair result can be complicated by the presence of external drug contamination. Decontamination procedures are included in hair analysis methods to remove external contamination, but the capacity of these washes to completely remove contamination for all drugs is controversial. It is evident that there is no consensus on the most effective decontamination procedure, nor can decontamination procedures consistently remove external drug contamination to less than reportable cut-offs for all analytes. ∆9-tetrahydrocannabinol deposited from cannabis smoke is mostly removed by organic solvents, whereas ionizable drugs are more effectively removed by an aqueous wash. Organizations such as the Society of Hair Testing recommend a hair decontamination procedure should include both an organic and aqueous washing step, which is in accordance with the reviewed literature. Studies involving a systematic evaluation of various solvents have shown that the most effective organic solvent was methanol and the most effective aqueous solvent contained sodium dodecyl sulfate detergent. If future systematic studies can demonstrate similar findings, a consensus on the most effective decontamination procedure for forensic hair analysis may be established

The effectiveness of decontamination procedures used in forensic hair analysis

Hair is a mainstream specimen used in forensic toxicology to determine drug use and exposure. However, the interpretation of an analytical hair result can be complicated by the presence of external drug contamination. Decontamination procedures are included in hair analysis methods to remove external contamination, but the capacity of these washes to completely remove contamination for all drugs is controversial. It is evident that there is no consensus on the most effective decontamination procedure, nor can decontamination procedures consistently remove external drug contamination to less than reportable cut-offs for all analytes. ∆9-tetrahydrocannabinol deposited from cannabis smoke is mostly removed by organic solvents, whereas ionizable drugs are more effectively removed by an aqueous wash. Organizations such as the Society of Hair Testing recommend a hair decontamination procedure should include both an organic and aqueous washing step, which is in accordance with the reviewed literature. Studies involving a systematic evaluation of various solvents have shown that the most effective organic solvent was methanol and the most effective aqueous solvent contained sodium dodecyl sulfate detergent. If future systematic studies can demonstrate similar findings, a consensus on the most effective decontamination procedure for forensic hair analysis may be established

A systematic investigation of forensic hair decontamination procedures and their limitations

The effectiveness of decontamination procedures used for the removal of external drug contamination in forensic hair analysis is an ongoing debate. This investigation evaluated wash methods complying with Society of Hair Testing (SoHT) guidelines and their capacity to remove cocaine (COC) and methamphetamine (MA) from artificially contaminated hair. The most effective decontamination method was determined using a systematic approach, involving (1) an initial washing solvent screen, (2) optimization of wash duration, (3) comparison of sequential wash methods, and (4) reanalysis of clinical hair samples. For analysis, hair was subjected to micro-pulverized methanolic extraction prior to quantitation by ultra-high performance liquid chromatography−tandem mass spectrometry (UHPLC−MS/MS). Methanol (MeOH) and 0.1 M phosphate buffer (pH 6) were the most effective organic and aqueous solvents, respectively, removing 28%38% of COC and 16%31% of MA. Wash durations longer than 3060 minutes did not remove additional amounts, and a more efficient sequential wash method was subsequently developed. Despite this, the interpretation of reportable results relative to the SoHT cut-off levels was unchanged for most clinical hair samples reanalyzed after washing by agitation for 30 minutes with MeOH. These findings highlight the inability of decontamination solvents to completely remove external COC and MA contamination from hair, including wash methods adhering to SoHT guidelines

Postmortem Metabolomics: Strategies to Assess Time-Dependent Postmortem Changes of Diazepam, Nordiazepam, Morphine, Codeine, Mirtazapine and Citalopram

Postmortem redistribution (PMR) can result in artificial drug concentration changes following death and complicate forensic case interpretation. Currently, no accurate methods for PMR prediction exist. Hence, alternative strategies were developed investigating the time-dependent postmortem behavior of diazepam, nordiazepam, morphine, codeine, mirtazapine and citalopram. For 477 authentic postmortem cases, femoral blood samples were collected at two postmortem time-points. All samples were quantified for drugs of abuse (targeted; liquid chromatography-tandem mass spectrometry LC-MS/MS) and characterized for small endogenous molecules (untargeted; gas chromatography-high resolution MS (GC-HRMS). Trends for significant time-dependent concentration decreases (diazepam (n = 137), nordiazepam (n = 126)), increases (mirtazapine (n = 55), citalopram (n = 50)) or minimal median postmortem changes (morphine (n = 122), codeine (n = 92)) could be observed. Robust mathematical mixed effect models were created for the generalized postmortem behavior of diazepam and nordiazepam, which could be used to back-calculate drug concentrations towards a time-point closer to the estimated time of death (caution: inter-individual variability). Significant correlations between time-dependent concentration changes of morphine, mirtazapine and citalopram with individual endogenous molecules could be determined; no correlation was deemed strong enough for successful a posteriori estimation on the occurrence of PMR for specific cases. The current dataset did successfully lead to a significant knowledge gain in further understanding the time-dependent postmortem behavior of the studied drugs (of abuse)