A review of multi-disciplinary decomposition research and key drivers of variation in decay

The decomposition of animal remains is a multifaceted process, involving ecological, biological, and chemical interactions. While the complexity is acknowledged through concepts like the necrobiome, it's unclear if this complexity is reflected in research. Appreciation of the complexity of decomposition is crucial for identifying sources of variation in estimations of time since death in medico-legal science, as well as building broader ecological knowledge of the decomposition process. To gain insights into the extent of multidisciplinary research in the field of decomposition science, we conducted an examination of peer-reviewed literature on four key drivers of variation: volatile organic compounds, microbes, drugs/toxins, and insects. Among 650 articles, we identified their scientific discipline, driver/s of variation investigated, and year of publication. We found that 19% explored relationships between two drivers, while only 4% investigated interactions between three. None considered all four drivers. Over the past three decades, there has been a steady increase in decomposition research publications, signifying its growing importance. Most research (79%) was linked to forensic science, highlighting opportunities for interdisciplinary collaboration in decomposition science. Overall, our review underscores the need to incorporate multidisciplinary approaches and theory into contemporary decomposition research.

Postmortem Analysis of Benzodiazepines in Human Bone by Gas Chromatography-Mass Spectrometry

A procedure based on gas chromatography-mass spectrometry was developed for the analysis of benzodiazepines (nordiazepam, oxazepam, lormetazepam, lorazepam, clonazepam, bromazepam and alprazolam) in postmortem human ribs. Powdered bone samples, including marrow remains inside, with the internal standard diazepam-d5 were subjected to enzymatic hydrolysis with 100 μL of β-glucoronidase and were incubated in sodium hydroxide for 1 h in a 70°C oven. Samples underwent liquid phase extraction and ethyl acetate was used as eluent. Chromatography was performed on a fused silica capillary column and the selected-ion-monitoring mode was used for analytes determination. The method was validated in the range 0.1-0.5 ng/mg (depending on the benzodiazepine) to 100 ng/mg with average values of recovery, matrix effect and process efficiency ranged from 83.2 to 94.3%, from 97.3 to 102.1% and from 80.5 to 91.2%, respectively. The intra- and inter-day accuracy was <15%. The procedure was tested in rib specimens obtained during routine autopsies from 20 cases where these benzodiazepines were found in blood. Benzodiazepines were detected in the combined bone and marrow samples in 60% of cases. Lorazepam was detected in bone in the range of 0.3-0.7 ng/mg, nordiazepam at 1.3-4.2 ng/mg and oxazepam at 1.1-1.2 ng/mg. To our knowledge, this protocol for the simultaneous analysis of these benzodiazepines is the first performed and validated using human ribs.

Detection of Chemical Weapon Nerve Agents in Bone by Liquid Chromatography-Mass Spectrometry

A recently proposed model for the incorporation of xenobiotics of forensic interest into the human skeleton suggests nerve agent metabolites may incorporate into bone at relatively elevated concentrations based on their unique chemical properties. To test the hypothesis that nerve agent metabolites interact with bone, methods for the extraction, isolation and semi-quantitative detection of nerve agent metabolites (MPA, EMPA, IMPA, iBuMPA, CMPA and PMPA, corresponding to the nerve agents VX, Russian VX, sarin, cyclosarin and soman, respectively) from osseous tissue were developed using liquid chromatography-mass spectrometry with both quadrupole time-of-flight and triple quadrupole (QqQ) instruments. The optimized methods were validated on the QqQ instrument. Despite high ion suppression, the achieved limits of detection (5-20 pg/g for four analytes; 350 pg/g for the fifth analyte) were lower than many of those published for the same analytes in other biomatrices, including serum and urine. These methods were tested on the skeletal remains of minipigs exposed to the chemical weapon VX in vivo. The VX metabolite was detected in multiple minipig bone samples; to the authors' knowledge, this is the first time in vivo nerve agent exposure has been detected from bone. Further, detected concentrations and diaphyseal-to-epiphyseal area count ratios reflect animal exposure history. Although the results are limited, they are promising, indicating that nerve agent metabolites may interact with bone as a pharmacokinetic compartment and can be extracted from bone postmortem. Additional studies, assessing the effects of different agents, exposure pathways and taphonomic variables, are needed; however, these results suggest the method may be used with human bone to detect use of chemical weapons from postmortem biomatrices even well after a suspected attack. More general implications for both nerve agent toxicology and skeletal toxicology are also discussed.

Analysis of Dextromethorphan and Three Metabolites in Decomposed Skeletal Tissues by UPLC-QToF-MS: Comparison of Acute and Repeated Drug Exposures

Ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-QToF-MS) analysis of dextromethorphan (DXM) and its metabolites-dextrorphan, 3-methoxymorphinan (3-MEM) and 3-hydroxymorphinan-in skeletal remains of rats exposed to DXM under different dosing patterns is described. Rats (n = 20) received DXM in one of four dosing patterns: acute (ACU1 or ACU2-100 or 200 mg/kg, i.p.; n = 5, respectively) or repeated (REP1 or REP2-3 doses of 25 or 50 mg/kg, i.p., 30 min apart; n = 5, respectively). Drug-free animals (n = 5) served as negative controls. Following euthanasia, the animals decomposed to skeleton outdoors. Bones were sorted by animal and skeletal element (vertebra, femur, pelvis, tibia, rib and skull), washed, air-dried and pulverized prior to dynamic methanolic drug extraction, filtration/pass-through extraction and analysis by UPLC-QToF-MS in positive electrospray ionization mode. Analyte levels (expressed as mass-normalized response ratios, RR/m) differed significantly between ACU1 and ACU2 (Mann-Whitney (MW), P < 0.05) in all skeletal elements for all analytes investigated, and between REP1 and REP2 in most skeletal elements for 3-MEM and 3-HOM, but in all skeletal elements for DXM. Between ACU1 and ACU2, and between REP1 and REP2, analyte level ratios (RRi/RRj) differed significantly (MW, P < 0.05) in 3/6 to 6/6 skeletal elements, depending on the ratios concerned, with no analyte level ratio differing significantly between both ACU1 vs ACU2 and REP1 vs REP2. Kruskal-Wallis (KW) analysis showed skeletal element to be a main effect for all analyte levels and analyte level ratios in all ACU and REP groups examined (P < 0.05). For data pooled only according to exposure pattern, KW analysis showed dose pattern to be a main effect for both analyte levels and analyte level ratios (P < 0.05). These data illustrate a dependence of these measures on dose, dose pattern and skeletal element, suggesting that some exposure patterns may be distinguished by toxicological analysis of bone.

Development and Validation of a Method for the Analysis of Bisoprolol and Atenolol in Human Bone

A method based on gas chromatography-mass spectrometry (GC-MS) is described for the determination of bisoprolol and atenolol in human bone. After the addition of lobivolol as internal standard, pulverized samples were incubated in acetonitrile for 1 h under ultrasounds. After adjusting the pH of the samples to 6, they were centrifuged, and the supernatants were subjected to solid phase extraction. Elution was achieved by using 3 mL of 2% ammonium hydroxide in 80:20 dichloromethane:isopropanol solution. Eluted samples were evaporated and derivatized. Chromatography was performed on a fused silica capillary column and analytes were determined in the selected-ion-monitoring (SIM) mode. The assay was validated in the range 0.1-0.3 ng/mg (depending on the drug) to 150 ng/mg, the mean absolute recoveries were 60% for bisoprolol and 106% for atenolol, the matrix effect was 69% for bisoprolol and 70% for atenolol and process efficiency was 41% for bisoprolol and 80% for atenolol. The intra- and inter-assay accuracy values were always better than 12%. The validated method was then applied to bone samples from two real forensic cases in which toxicological analysis in blood were positive for atenolol in the first case (0.65 µg/mL) and bisoprolol in the second case (0.06 µg/mL). Atenolol was found in bone samples from the corresponding case at the approximate concentration of 148 ng/mg and bisoprolol was found at 8 ng/mg.

Semi-quantitative analysis of tramadol, dextromethorphan, and metabolites in decomposed skeletal tissues by ultra performance liquid chromatography quadrupole time of flight mass spectrometry

The use of filtration/pass-through extraction (FPTE) and ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-qTOF-MS) to detect tramadol (TRAM), dextromethorphan (DXM), and metabolites from skeletal remains is described. Rats (n=5) received 50 mg/kg tramadol and were euthanized by CO₂ asphyxiation approximately 30 minutes post-dose. Rats (n=4) received 75 mg/kg dextromethorphan and were euthanized by CO₂ asphyxiation approximately 45 minutes post-dose. Remains decomposed to skeleton outdoors and vertebral bones were collected. Bones were cleaned, dried, and pulverized to a fine powder. Bones underwent dynamic methanolic extraction followed by FPTE before analysis using UPLC-qTOF-MS. Recovery was at least 90% of maximal value within the first 10 minutes of methanolic extraction for all samples assayed. Analytical response was measured over the concentration range of 1-500 ng/mL, with precision and bias <20% in triplicate analyses of all calibrators, and a limit of detection of 1 ng/mL for TRAM, DXM, and all metabolites. The vertebral bone analyzed using this method detected TRAM, DXM, and their respective metabolites in all samples analyzed.