Semiquantitative screening of trace combustion-derived volatile substances in the blood of fire victims using NeedlEx

Various autopsy findings are used for the diagnosis of burning death, including inhalation injury, soot in the respiratory tract, vital reaction, blood carboxyhemoglobin (COHb), and blood cyanide. However, not all findings are necessarily complete, and autopsy diagnosis can be difficult in cases where there are few findings. In this study, we analyzed combustion-derived volatile substances (CVSs) in post-mortem blood in fire-related cases, focusing on those that occur when buildings and furniture thermally decompose during a fire, and evaluated these as potential new autopsy findings. The blood CVSs of 61 fire-related cases from 2013 to 2015 were analyzed by a rapid and operationally simple method that employed a gas chromatograph-mass spectrometer coupled to a NeedlEx A total of 39 types of aliphatic and aromatic hydrocarbons were detected in the blood of fire victims. They could be detected even in post-mortem blood with COHb <10%, cyanide concentration <0.25μg/ml, and no soot in the respiratory tract. Styrene was detected in all cases except for one case of burning suicide with kerosene. The blood CVSs could be readily differentiated between the victims of building fires, self-immolation with kerosene, and self-immolation with gasoline: the presence of alpha-methylstyrene with a large amount styrene indicated a building fire; the detection of C9-C12 aliphatic hydrocarbons and C3 alkylbenzenes suggested a kerosene-related fire; and the detection of large amount of toluene and C3 alkylbenzenes indicated a gasoline-related fire. The number of blood CVSs detected for the building fire victims showed correlations with COHb level, cyanide concentration, and the amount of soot. With self-immolation, the number of blood CVSs detected showed weak correlation with COHb level, cyanide concentration, or amount of soot. Analysis of blood CVSs enabled the identification of the type of fire-related death, which is impossible by conventional autopsy findings.