Analysis of volatile organic compounds released from the decay of surrogate human models simulating victims of collapsed buildings by thermal desorption-comprehensive two-dimensional gas chromatography-time of flight mass spectrometry.

Field experiments were devised to mimic the entrapment conditions under the rubble of collapsed buildings aiming to investigate the evolution of volatile organic compounds (VOCs) during the early dead body decomposition stage. Three pig carcasses were placed inside concrete tunnels of a search and rescue (SAR) operational field terrain for simulating the entrapment environment after a building collapse. The experimental campaign employed both laboratory and on-site analytical methods running in parallel. The current work focuses only on the results of the laboratory method using thermal desorption coupled to comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (TD-GC×GC-TOF MS). The flow-modulated TD-GC×GC-TOF MS provided enhanced separation of the VOC profile and served as a reference method for the evaluation of the on-site analytical methods in the current experimental campaign. Bespoke software was used to deconvolve the VOC profile to extract as much information as possible into peak lists. In total, 288 unique VOCs were identified (i.e., not found in blank samples). The majority were aliphatics (172), aromatics (25) and nitrogen compounds (19), followed by ketones (17), esters (13), alcohols (12), aldehydes (11), sulfur (9), miscellaneous (8) and acid compounds (2). The TD-GC×GC-TOF MS proved to be a sensitive and powerful system for resolving the chemical puzzle of above-ground "scent of death".

Dynamic vapor generator that simulates transient odor emissions of victims entrapped in the voids of collapsed buildings.

The design, development, and validation of a dynamic vapor generator are presented. The generator simulates human scent (odor) emissions from trapped victims in the voids of collapsed buildings. The validation of the device was carried out using a reference detector: a quadrupole mass spectrometer equipped with a pulsed sampling (PS-MS) system. A series of experiments were conducted for evaluating the simulator's performance, defining types and weights of different factors, and proposing further optimization of the device. The developed device enabled the production of stable and transient odor profiles in a controllable and reproducible way (relative standard deviation, RSD < 11%) at ppbv to low ppmv concentrations and allowed emission durations up to 30 min. Moreover, the factors affecting its optimum performance (i.e., evaporation chamber temperature, air flow rate through the mixing chamber, air flow rate through the evaporation chamber, and type of compound) were evaluated through an analysis of variance (ANOVA) tool revealing the next steps toward optimizing the generator. The developed simulator, potentially, can also serve the need for calibrating and evaluating the performance of analytical devices (e.g., gas chromatographers, ion mobility spectrometers, mass spectrometers, sensors, e-noses) in the field. Furthermore, it can contribute in better training of urban search and rescue (USaR) canines.

A scale-up field experiment for the monitoring of a burning process using chemical, audio, and video sensors.

Fires are becoming more violent and frequent resulting in major economic losses and long-lasting effects on communities and ecosystems; thus, efficient fire monitoring is becoming a necessity. A novel triple multi-sensor approach was developed for monitoring and studying the burning of dry forest fuel in an open field scheduled experiment; chemical, optical, and acoustical sensors were combined to record the fire spread. The results of this integrated field campaign for real-time monitoring of the fire event are presented and discussed. Chemical analysis, despite its limitations, corresponded to the burning process with a minor time delay. Nevertheless, the evolution profile of CO2, CO, NO, and O2 were detected and monitored. The chemical monitoring of smoke components enabled the observing of the different fire phases (flaming, smoldering) based on the emissions identified in each phase. The analysis of fire acoustical signals presented accurate and timely response to the fire event. In the same content, the use of a thermographic camera, for monitoring the biomass burning, was also considerable (both profiles of the intensities of average gray and red component greater than 230) and presented similar promising potentials to audio results. Further work is needed towards integrating sensors signals for automation purposes leading to potential applications in real situations.

Physiology and biochemistry of human subjects during entrapment.

A classification of various categories of entrapped people under the ruins of collapsed buildings after earthquakes, technical failures or explosions is proposed. Type and degree of injury at the moment of building collapse and duration of entrapment are the two basic parameters in this classification. The aim is to provide sources and types of volatile organic compounds (VOCs) that can be used for establishing a new method for locating entrapped victims based on human chemical signatures. Potential target compounds, among others, are ammonia, acetone, isoprene, dimethylsulfide, dimethyldisulfide and trimethylamine. In this context, the possible neuroendocrine, metabolic and physical responses of potential victims during the different types of entrapment are correlated with the sources of VOCs such as expired air, urine, blood and sweat. The proposed classification scheme was developed as part of an integrated research project which investigates the use of combined audio, video and chemical methods for the early location of entrapped people under the ruins of collapsed buildings.

The trapped human experiment.

This experiment observed the evolution of metabolite plumes from a human trapped in a simulation of a collapsed building. Ten participants took it in turns over five days to lie in a simulation of a collapsed building and eight of them completed the 6 h protocol while their breath, sweat and skin metabolites were passed through a simulation of a collapsed glass-clad reinforced-concrete building. Safety, welfare and environmental parameters were monitored continuously, and active adsorbent sampling for thermal desorption GC-MS, on-line and embedded CO, CO(2) and O(2) monitoring, aspirating ion mobility spectrometry with integrated semiconductor gas sensors, direct injection GC-ion mobility spectrometry, active sampling thermal desorption GC-differential mobility spectrometry and a prototype remote early detection system for survivor location were used to monitor the evolution of the metabolite plumes that were generated. Oxygen levels within the void simulator were allowed to fall no lower than 19.1% (v). Concurrent levels of carbon dioxide built up to an average level of 1.6% (v) in the breathing zone of the participants. Temperature, humidity, carbon dioxide levels and the physiological measurements were consistent with a reproducible methodology that enabled the metabolite plumes to be sampled and characterized from the different parts of the experiment. Welfare and safety data were satisfactory with pulse rates, blood pressures and oxygenation, all within levels consistent with healthy adults. Up to 12 in-test welfare assessments per participant and a six-week follow-up Stanford Acute Stress Response Questionnaire indicated that the researchers and participants did not experience any adverse effects from their involvement in the study. Preliminary observations confirmed that CO(2), NH(3) and acetone were effective markers for trapped humans, although interactions with water absorbed in building debris needed further study. An unexpected observation from the NH(3) channel was the suppression of NH(3) during those periods when the participants slept, and this will be the subject of further study, as will be the detailed analysis of the casualty detection data obtained from the seven instruments used.

Combined chemical and optical methods for monitoring the early decay stages of surrogate human models.

As the body decays shortly after death, a variety of gases and volatile organic compounds (VOCs) constantly emanate. Ethical and practical reasons limit the use of human corpses in controlled, time-dependent, intervening experiments for monitoring the chemistry of body decay. Therefore the utilization of pig carcasses serves as a potential surrogate to human models. The aim of this work was to study buried body decay in conditions of entrapment in collapsed buildings. Six domestic pigs were used to study carcass decay. They were enclosed in plastic body bags after being partially buried with rubbles, resembling entrapment in collapsed buildings. Three experimental cycles were performed, employing two pig carcasses in each cycle; VOCs and inorganic gases were measured daily, along with daily visible and thermal images. VOCs were collected in standard sorbent tubes and subsequently analyzed using a Thermal Desorption/Gas Chromatograph/high sensitivity bench-top Time-of-Flight Mass Spectrometer (TD/GC/TOF-MS). A comprehensive, stage by stage, detailed information on the decay process is being presented based on the experimental macroscopic observations, justifying thus the use of pig carcasses as surrogate material. A variety of VOCs were identified including almost all chemical classes: sulfur, nitrogen, oxygen compounds (aldehydes, alcohols, ketones, acids and esters), hydrocarbons, fluorides and chlorides. Carcasses obtained from a pig farm resulted in more sulfur and nitrogen cadaveric volatiles. Carbon dioxide was by far the most abundant inorganic gas identified along with carbon monoxide, hydrogen sulfide and sulfur dioxide. Visual monitoring was based on video captured images allowing for macroscopic observations, while thermal camera monitoring which is mostly temperature dependent, resulted in highlighting the local micro-changes on the carcasses, as a result of the intense microbial activity. The combination of chemical and optical methods proved very useful and informative, uncovering hidden aspects of the early stages of decay and also guiding in the development of combined chemical and imaging methods for the detection of dead bodies.

Environmental aspects of VOCs evolved in the early stages of human decomposition.

In the present study, the time profile, measured as "accumulation", of volatile organic compounds (VOCs) produced during the early stages of human decomposition was investigated. A human cadaver was placed in a sealed bag at approximately the 4th day after death. Evolved VOCs were monitored for 24 h by sampling at different time intervals. VOCs produced were analyzed by thermal desorption/gas chromatography/mass spectrometry (TD/GC/MS). Over 30 substances were identified in total. These included mainly aliphatic and aromatic hydrocarbons, oxygenated compounds (alcohols, aldehydes, ketones) and organic sulfides. The last were the most prominent class of compounds identified. Eleven compounds were present in all the sampling cycles and constitute a "common core": ethanol, 2-propanone, dimethyl disulfide, methyl benzene, octane, 2-butanone, methyl ethyl disulfide, dimethyl trisulfide and o-, m- and p-xylenes. The last sampling cycle yielded the most abundant compounds in number and quantities. Inorganic gases such as CO2, CO, NH3 and H2S were also determined. The fundamental physicochemical properties of the evolved VOCs were used for evaluating their environmental impacts. It appears that the decay process, which is a dynamic procedure, can provide chemical signals that might be detected and properly evaluated by experts in the fields of forensic sciences, search and rescue units and environmental scientists.

Integration of field chemical data in initial risk assessment of forest fire smoke.

A risk assessment framework was used to assess the risks of forest fire smoke (ffs) to the exposed communities, critical infrastructures and the environment. The present work is focused on the planning and problem formulation phases of this risk assessment procedure. Specifically, as part of the problem formulation phase, integration of the available ffs chemical data was carried out by answering critical questions regarding the ffs. In this way, critical factors have been identified, which mostly define and characterize ffs as a cause of problems and possible symptoms. The integrated information can be used in order to determine assessment endpoints, conceptual models, and risk hypotheses, as presented in an indicative example referred to a simple risk scenario. This work, enhanced with additional risk scenarios, can be used for the next phases of the risk assessment procedure, such as risk analysis and risk characterization. Future research needs for adequate evaluation of ffs impacts on communities, infrastructures, and the environment are also discussed.

Analysis of expired air of fasting male monks at Mount Athos.

Expired air chemical analysis is investigated as a search and locate method for the early detection of entrapped people under the ruins of collapsed buildings after an earthquake. Fasting individuals were examined as a group that simulates the medical status of some of such victims. Exhaled air from seven fasting male monks (after 63 h) was analysed using thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) analysis. Over 150 volatile organic compounds (VOCs) were identified and the 43 most frequent are presented. Acetone showed by far the highest "positive alveolar gradient". Other compounds included phenol, di-limonene, 2-pentanone, isoprene and acetaldehyde. Quantitative results showed a 30-fold increase of acetone concentration (5.8 ppmv) compared to control measurements of a volunteer. Breath acetone was also identified through a portable gas chromatography-ion mobility spectrometer showing possible, under certain conditions, effectiveness of the method in the field.

On-line monitoring of pine needles combustion emissions in the presence of fire retardant using a "thermogravimetry (TG)-bridge/mass spectrometry method".

In this work a new method called TG-bridge/mass spectrometry is presented, for the on-line monitoring of the pine needles combustion emissions in a common lab furnace. The TG-bridge (thermogravimetry-bridge) system has been developed in-house as a TG-MS (thermogravimetry-mass spectrometry) interface, for TG-MS analysis. In this work, TG-bridge was used for directly sampling of the combustion emissions from the inside of the furnace and transferring them into the mass spectrometer (MS), without disturbing the sub-pressure conditions inside the MS ion source. The effect of Fire-Trol 931 (a long-term fire retardant) on the emissions, produced during the combustion of pine needles, is tested in the lab for future application in the field. It was shown that in treated samples, increased evolution of ammonia and aromatic compounds took place, compared to untreated samples. Maximum concentrations of specific compounds, such as benzene and toluene, evolved during the combustion experiments in the furnace, were determined.

A study of volatile organic compounds evolved from the decaying human body.

Two men were found dead near the island of Samos, Greece, in the Mediterranean sea. The estimated time of death for both victims was 3-4 weeks. Autopsy revealed no remarkable external injuries or acute poisoning. The exact cause of death remained unclear because the bodies had advanced decomposition. Volatile organic compounds (VOCs) evolved from these two corpses were determined by thermal desorption/gas chromatography/mass spectrometry analysis (TD/GC/MS). Over 80 substances have been identified and quantified. The most prominent among them were dimethyl disulfide (13.39 nmol/L), toluene (10.11 nmol/L), hexane (5.58 nmol/L), benzene 1,2,4-trimethyl (4.04 nmol/L), 2-propanone (3.84 nmol/L), 3-pentanone (3.59 nmol/L). Qualitative and quantitative differences among the evolved VOCs and CO2 mean concentration values might indicate different rates of decomposition between the two bodies. The study of the evolved VOCs appears to be a promising adjunct to the forensic pathologist as they may offer important information which can be used in his final evaluation.

Preliminary investigation of using volatile organic compounds from human expired air, blood and urine for locating entrapped people in earthquakes.

A preliminary investigation on the possibility of using volatile organic compounds (VOCs) determination of expired air, blood and urine, for the early location of entrapped people in earthquakes, has been carried out. A group of 15 healthy subjects has been sampled. The identification of a common "core" of substances might provide indications of human presence that can be used for the development of a real time field analytical method for the on site detection of entrapped people. Expired air samples have been analyzed by thermal desorption GC/MS and VOCs from blood and urine by headspace SPME-GC/MS. Acetone was the only compound found common in all three matrices. Isoprene was found in both expired air and blood samples. Acetone and isoprene along with a number of saturated hydrocarbons were among the major constituents identified in expired air analysis. Various ketones (2-pentanone, 4-heptanone, 2-butanone) were also determined over urine specimens. Using the techniques and methods of field analytical chemistry and technology appears to be the proper approach for applying the results of the present study in real situations.

Short column gas chromatography-mass spectrometry and principal component analysis for the identification of coeluted substances in doping control analysis.

The identification of four doping control substances in an artificial mixture, using short column gas chromatography-mass spectrometry (GC-MS) analysis was examined. Two chromatographic peaks were recorded in the chromatogram, using a short capillary column (1.8 m) at an oven temperature of 180 degrees C. The first peak was associated with a mixture of a solvent derivative and an artifact. The second one corresponded to the mixture of four control substances. Principal component analysis was applied on a selected GC-MS data set of the latter peak to determine clear full spectra of pure substances from mixture spectra. The time of GC-MS analysis was significantly reduced to less than 1 min from 30 min which is a typical GC-MS analysis time, using standard methods of doping control analysis.