Detecting volatile organic compounds to locate human remains in a simulated collapsed building

Could Necroleachate Be the Cemetery's Sewage? A Panorama from Brazilian Legislation

Cemeteries can be compared to landfills, as the leachate produced in these areas, also known as necroleachate, can be environmentally transported, polluting groundwater, surface water, and soil. In Brazil, to ensure no negative environmental impacts and public health risks, cemetery management is the responsibility of states and municipalities. In this context, this article aims to discuss Brazilian sanitary-environmental legislation concerning cemetery waste management. Only half of all Brazilian states have established sanitary-environmental cemetery legislation, and only 19 municipalities have specific laws. These laws, however, are broad and contain many gaps. Necroleachate care and control require both sanitary and environmental assessments to avoid environmental vulnerability and contamination risks for populations inhabiting surrounding areas. In this regard, new water analysis parameters in environmentally vulnerable areas should be established to control the population's drinking water quality, such as the detection of C. perfringens. Furthermore, the construction of vertical cemeteries instead of horizontal ones and the adoption of cremation procedures should also be considered. This assessment comprises a novel research framework, as no studies on the impact of Brazilian laws on environmental necroleachate contamination are available to date.

The smell of death. State-of-the-art and future research directions

The decomposition of a body is inseparably associated with the release of several types of odors. This phenomenon has been used in the training of sniffer dogs for decades. The odor profile associated with decomposition consists of a range of volatile organic compounds (VOCs), chemical composition of which varies over time, temperature, environmental conditions, and the type of microorganisms, and insects colonizing the carcass. Mercaptans are responsible for the bad smell associated with corpses; however, there are no unified recommendations for conducting forensic analysis based on the detectable odor of revealed corpses and previous research on VOCs shows differing results. The aim of this review is to systematize the current knowledge on the type of volatile organic compounds related to the decomposition process, depending on a few variables. This knowledge will improve the methods of VOCs detection and analysis to be used in modern forensic diagnostics and improve the methods of training dogs for forensic applications.

The use of lipids from textiles as soft-tissue biomarkers of human decomposition

The ability to determine the post-mortem interval (PMI) in complex death investigations involving human remains, is a vital task faced by law enforcement. Establishing the PMI in a case can significantly aid in the reconstruction of forensically relevant events surrounding that death. However, due to the complexities surrounding the decomposition of human remains, the determination of the PMI still remains a challenge in some cases. Thus, the identification of biomarkers of human decomposition are an emerging, and essential, area of research. Previous studies have also demonstrated great success in the use of textiles as a host to indirectly capture decomposition by-products. This study reports the successful adaptation and optimisation of an analytical chemical workflow for the targeted analysis of lipids from textiles associated with decomposing human remains using gas-chromatography (GC) coupled with tandem mass spectrometry (MS/MS). This study discusses novel information regarding the complex challenges of matrix effects observed with decomposition samples. In addition, the first lipid profiles obtained from textiles associated with two decomposing human donors from the Australian Facility for Taphonomic Experimental Research (AFTER) using GC-MS/MS are presented.

Simulating comprehensive two-dimensional gas chromatography mass spectrometry data with realistic run-to-run shifting to evaluate the robustness of tile-based Fisher ratio analysis

Untargeted analysis of comprehensive two-dimensional (2D) gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS) data has the potential to be hindered by run-to-run retention time shifting. To address this challenge, tile-based Fisher ratio (F-ratio) analysis (FRA) has been developed, which utilizes a supervised, untargeted approach involving a chromatographic segmentation routine termed "tiling" combined with the ANOVA F-ratio statistic to discover class-distinguishing analytes while minimizing false positives arising from shifting. The tiling algorithm is designed to account for retention shifting in both separation dimensions. Although applications of FRA have been reported, there remains a need to thoroughly evaluate the robustness of FRA for different levels of run-to-run retention shifting in order to broaden the scope of its application. To this end, a novel method of simulating GC×GC-TOFMS chromatograms with realistic run-to-run shifting is presented by random generation of low-frequency "shift functions". The dimensionless retention-time precision, <δ_r>, which is four times the standard deviation in retention time normalized to the peak width-at-base is used as a key modeling variable along with the 2D chromatographic saturation, α_e,2D, and within-class relative standard deviation in peak area, RSD_wc. We demonstrate that all three of these variables operate together to impact true positive discovery. To quantify the "success" of true positive discovery, GC×GC-TOFMS datasets for various combinations of <δ_r>, α_e,2D, and RSD_wc were simulated and then analyzed by FRA using a wide range of relative tile areas (RTA), which is a dimensionless measure of tile size. Since each hit in the FRA hit list was known a priori as either a true or false positive based on the simulation inputs, receiver operating characteristic (ROC) curves were readily constructed. Then, the area under the ROC curve (AUROC) was used as a metric for discovery "success" for various combinations of the modeling variables. Based on the results of this study, recommendations for tile size selection and experimental design are provided, and further supported by comparison to previous tile-based FRA applications. For instance, values for <δ_r>, α_e,2D, and RSD_wc obtained from a GC×GC-TOFMS dataset of yeast metabolites suggested an optimum RTA of 6.25, corresponding closely to the RTA of 4.00 employed in the study, implying the simulation results obtained here can be generalized to real datasets.

A headspace collection chamber for whole body volatilomics

The human body secretes a complex blend of volatile organic compounds (VOCs) via the skin, breath and bodily fluids. In this study, we have developed a headspace collection chamber for whole body volatilome profiling.