Application of Headspace Gas Chromatography with Flame Ionization Detector for Determination of Carboxyhemoglobin in Forensic Blood Samples

The level of carboxyhemoglobin (CO-Hb) in the forensic blood sample is a critical evidence to the conclusion that the fatality was related to CO poisoning or other reason causing death. In this study, we validated the method for CO-Hb determination in blood using headspace gas chromatography-flame ionization detector (HS-GC/FID) for further application to the analysis of forensic samples. The liberated CO from CO-Hb was reduced to methane by a specific catalyst and then analyzed by GC-FID. The quantitative range for CO-Hb was from 2.5 to 100% with the limit of detection down to 0.5%. The average recovery at different levels of CO-Hb was from 96.8 to 98.5% with high repeatability and intermediate precision. The obtained parameters presented that the method was highly sensitive and accurate for CO-Hb determination in blood samples. The method was also applied to the analysis of 27 forensic samples that had the questionable cause of death. Eighteen samples were related to CO poisoning with the level of CO-Hb exceeding 15%. All the results demonstrated that this method could be applied for forensic diagnosis.