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.

Comparison of Different Analytical Methods for the Determination of Carbon Monoxide in Postmortem Blood.

The determination of carbon monoxide (CO) and carboxyhemoglobin (COHb) is of utmost importance in forensic toxicology to determine the cause of death in cases of CO poisoning, fire, and explosions. To this end, reliable and updated analytical methods are required. In this paper, four different methods for the determination of carbon monoxide in postmortem blood samples were compared: (i) the spectrophotometric determination of COHb applying the method proposed by Rodkey and modified by Beutler-West, (ii) the spectrophotometric determination of CO using a micro-diffusion-based method, (iii) the determination of CO by gas chromatography coupled to a TCD detector, and (iv) the determination of COHb by blood gas analysis. Three postmortem blood samples were analyzed with all methods, and the results were comparable. The applied methodologies showed different features depending on the sensitivity, sample preparation, and volume. The HS-GC/TCD method in our hand was the most appropriate, on postmortem samples, and versatile to apply. Unfortunately, only a limited number of postmortem blood samples were available for this study due to the rarity of that kind of intoxication in our jurisdiction.

Analysis of trace impurities in neon by a customized gas chromatography.

Excimer lasers, widely used in the semiconductor industry, are crucial for analyzing the purity of premix laser gases for the purpose of controlling stable laser output power. In this study, we designed a system for analyzing impurities in pure neon (Ne) base gas by customized GC. Impurities in pure neon (H2 and He), which cannot be analyzed at the sub-µmol/mol level using commercial GC detectors, were analyzed by a customized pulsed-discharge Ne ionization detector (PDNeD) and a pressurized injection thermal conductivity detector using Ne as the carrier gas (Pres. Inj. Ne-TCD). From the results, trace species in Ne were identified with the following detection limits: H2, 0.378µmol/mol; O2, 0.119µmol/mol; CH4, 0.880µmol/mol; CO, 0.263µmol/mol; CO2, 0.162µmol/mol (PDNeD); and He, 0.190µmol/mol (Pres. Inj. Ne-TCD). This PDNeD and pressurized injection Ne-TCD technique thus developed permit the quantification of trace impurities present in high-purity Ne.