Two cases of suicide by asphyxiation due to helium and argon

High-Precision Trace Hydrogen Sensing by Multipass Raman Scattering

Despite its growing importance in the energy generation and storage industry, the detection of hydrogen in trace concentrations remains challenging, as established optical absorption methods are ineffective in probing homonuclear diatomics. Besides indirect detection approaches using, e.g., chemically sensitized microdevices, Raman scattering has shown promise as an alternative direct method of unambiguous hydrogen chemical fingerprinting. We investigated the suitability of feedback-assisted multipass spontaneous Raman scattering for this task and examined the precision with which hydrogen can be sensed at concentrations below 2 parts per million. A limit of detection of 60, 30, and 20 parts per billion was obtained at a pressure of 0.2 MPa in a 10-min-long, 120-min-long, and 720-min-long measurement, respectively, with the lowest concentration probed being 75 parts per billion. Various methods of signal extraction were compared, including asymmetric multi-peak fitting, which allowed the resolution of concentration steps of 50 parts per billion, determining the ambient air hydrogen concentration with an uncertainty level of 20 parts per billion.

Helium Suicide, a Rapid and Painless Asphyxia: Toxicological Findings

Suicide by helium inhalation has become increasingly common in the last few decades in Europe and the US because it produces a quick and painless death. Inhaled-gas suicides can easily be assessed through death scene investigation and autopsy. However, helium is a colorless and odorless inert gas that unfortunately cannot be detected using standard toxicological analysis. A successful gas analysis was performed following the suicide of a 17-year-old female. For the detection of helium, central/peripheral blood samples and gaseous samples from the esophagus, stomach, and upper and lower respiratory airways (from the trachea and the primary left and right bronchia) were collected with a gastight syringe, ensuring minimal dilution. Qualitative analyses were positive in all gaseous samples. Quantitative analyses were performed using a special gas-inlet system with a vacuum by which the sample can be transferred to a mass spectrometer, reducing the risk of contamination. Helium concentrations were 20.16% from the trachea, 12.33% from the right lung, and 1.5% from the stomach. Based on the high levels of helium, the cause and manner of death were assessed as asphyxia suicide by inhalation of helium. Therefore, toxicological analyses should always be applied in order to gain evidence of inhaled gas in gaseous samples.

Samobójstwo przy użyciu helu – opis przypadku

W ostatnich latach obserwuje się wzrost liczby samobójstw z wykorzystaniem helu. Zgony z użyciem tego gazu są szybkie i nie towarzyszy im uczucie duszności. W niniejszej pracy przedstawiono wyniki badania pośmiertnego kobiety, która popełniła samobójstwo poprzez inhalację helu. Sekcja zwłok nie wykazała żadnych zmian pourazowych, natomiast badanie TK wykazało obecność dużej ilości gazu w naczyniach żylnych i tętniczych całego ciała oraz w jamach serca. W ocenie obrazów PMCT uwzględniono także zmiany wynikające z procesów rozkładowych. Rezultaty przeprowadzonej diagnostyki potwierdzają wyniki wcześniejszych doniesień, które wskazywały, iż wdychanie dużych ilości helu prowadzi do śmierci nie tylko (jak wcześniej sądzono) w mechanizmie wypierania tlenu, ale także poprzez powstawanie zatorów gazowych. Suicidal helium inhalation – case report A significant increase in the number of suicides with the use of helium has been observed in recent years. Deaths with its use are quick and are not accompanied by a feeling of breathlessness. This paper presents the results of a post-mortem examination of a woman who committed suicide by inhaling helium. Conventional postmortem examination did not reveal any post-traumatic changes, while a computed tomography (CT) scans showed the presence of a large amount of gas in the veins and arteries of the whole body and in the heart chambers. In the assessment of postmortem computed tomography (PMCT) images, changes resulting from putrefaction were also taken into account. The results of the diagnostics carried out confirm the results of previous reports, which indicated that inhalation of large amounts of helium leads to death not only (as previously thought) in the oxygen displacement mechanism, but also through the formation of gas embolisms.

Detection of helium in a fire victim: A case report

We report here detection of helium in specimens derived from a burn autopsy case. A male was found in a burnt bedroom. Part of a heat-denatured plastic bag, sealing tape, and flexible tubing remained on his head and neck. In addition, five helium tanks were found near him. His history in conjunction with the discovery conditions suggested a suicide attempt by inhalation of helium. The body had extensive first to fourth degree burns caused by heat. A small amount of soot was deposited in the respiratory tract. Except for the thermal burns, no other injuries were found. Toxicologically, the blood carboxyhemoglobin saturation levels were less than 6%, while combustion-derived volatile hydrocarbons such as benzene or toluene were detected in the blood. In addition, tracheal gas, gastric gas, headspace gas of lung tissue, brain, and heart blood were collected during autopsy for detection of helium. Analysis was performed using headspace gas chromatography with a thermal conductivity detector. Helium was detected in all of the samples tested. Etizolam at a low limit of therapeutic concentration or less was detected in the blood. Neither ethanol nor other drugs of abuse were detected in his blood or urine. Autopsy findings and experiments suggest that the victim inhaled helium and was still alive when a fire broke out. The cause of his death was diagnosed as death from fire and flames. The present result suggests that helium may remain in a burned body and that investigation of helium in cases of fire-related deaths is informative for determination of the cause of death or confirmation of the ante mortem involvement of helium.

Quantitative Determination of H2 in Human Blood by 22Ne-aided Gas Chromatography-Mass Spectrometry Using a Single Quadrupole Instrument

Here, we present a quantitative method for H2 detection by gas chromatography-selected ion monitoring-mass spectrometry (GC-SIM-MS) using a single quadrupole instrument. Additionally, the developed method was applied to the detection of H2 in human blood by GC-SIM-MS analysis using the existing 22Ne in air as an internal standard (IS). H2 was analyzed by GC-SIM-MS using a single quadrupole instrument with double TC-Molsieve 5A capillary columns for the separation of permanent gases. The detections of H2 (analyte) and 22Ne (IS) were performed at m/z 2 and 22, respectively, by GC-SIM-MS. The analyte and IS were separated using He as the carrier gas. The ratio of the peak area of H2 to 22Ne was employed to obtain a calibration curve for H2 determination in the gas phase. The proposed GC-SIM-MS method exhibited high sensitivity in terms of the limits of detection (LOD) (1.7 ppm) and quantitation (LOQ) (5.8 ppm) for H2 analysis. The developed quantitative assay of H2 in the headspace of blood samples achieved high repeatability with a relative standard deviation (RSD) of 1.4 - 4.7%. We successfully detected and quantified H2 in the headspaces of vacuum blood-collection tubes containing whole blood from 11 deceased individuals with several causes of death by employing the developed GC-SIM-MS method. The quantitative value of H2 ranged from 5 to 905 ppm. The proposed GC-SIM-MS method was applicable to the quantitative assay of H2 in biological samples without tedious pretreatment requirements.

How common are suicides using nitrous oxide?

Analysis of autopsy cases of suicide from Forensic Science South Australia files (2003–2017) where helium, nitrogen or nitrous oxide gas had been used revealed that only 2/58 (3.5%) cases utilised nitrous oxide; the remainder of cases had used helium or nitrogen. The two cases are presented here. In case 1, a 48-year-old man was found completely encased in a plastic bag with a hose connected to an opened cylinder of nitrous oxide. In case 2, a 27-year-old woman was found with a plastic bag over her head, tied around her neck, with a tube connected to a small canister of nitrous oxide. There were approximately 20 empty canisters of nitrous oxide nearby. Death in both cases was due to nitrous oxide augmentation of plastic bag asphyxia, manner suicide. The relative ease with which helium and nitrogen cylinders containing large amounts of gas can be obtained may explain the low numbers of suicides utilising nitrous oxide.

A new and sensitive method for quantitative determination of helium in human blood by gas chromatography-mass spectrometry using naturally existing neon-21 as internal standard

Purpose

In this study, we proposed a new sensitive quantitative method for detecting helium in human blood by gas chromatography–selected-ion monitoring (SIM)-mass spectrometry (GC–SIM-MS) using naturally existing neon-21 in air as internal standard (IS).

Methods

GC–SIM-MS analysis was performed on a double TC-Molsieve 5A capillary column (total length 60 m) for the separation of permanent gases by a single-run experiment. By using hydrogen as the carrier gas, the analyte (helium) and IS (neon-21) were separated on the double column, and detected at m/z 4 and 21, respectively. The ratio of the peak area of helium-to-neon-21 was used for obtaining the calibration curve for helium determination.

Results

The limits of detection and quantification of helium under the present GC–SIM-MS conditions were as low as 1.8 and 6.0 ppm, respectively. The proposed GC–SIM-MS method also showed high repeatability with relative standard deviation at 1.3–5.1%, indicating that the use of neon-21 as IS was valid for reliable helium assays. The successful quantification of helium in the headspace of vacuum blood collection tubes containing the whole blood from four humans who died of helium inhalation was achieved using the proposed neon-21-aided GC–SIM-MS method; the values obtained for helium were 24–497 ppm.

Conclusions

The proposed GC–SIM-MS method in combination with the naturally existing neon-21 as IS is most recommendable for quantitative assays of helium in biological samples because of its simplicity and extremely high sensitivity.

Indirect hydrogen analysis by gas chromatography coupled to mass spectrometry (GC-MS)

Gas chromatography (GC) is an analytical tool very useful to investigate the composition of gaseous mixtures. The different gases are separated by specific columns but, if hydrogen (H2 ) is present in the sample, its detection can be performed by a thermal conductivity detector or a helium ionization detector. Indeed, coupled to GC, no other detector can perform this detection except the expensive atomic emission detector. Based on the detection and analysis of H2 isotopes by low-pressure chemical ionization mass spectrometry (MS), a new method for H2 detection by GC coupled to MS with an electron ionization ion source and a quadrupole analyser is presented. The presence of H2 in a gaseous mixture could easily be put in evidence by the monitoring of the molecular ion of the protonated carrier gas.