Comparative Evaluation of Carboxyhemoglobin Quantification in Postmortem Whole Blood by CO-Oximetry and Headspace Gas Chromatography with Flame Ionization Detection and Atom Absorption Spectrophotometry.

This article focuses on a comparative evaluation of two methods for determining carboxyhemoglobin (COHb) levels in postmortem whole blood: CO-oximetry measuring at 128 wavelengths and headspace gas chromatography with flame ionization detection combined with atomic absorption spectrophotometry (HS-GC--FID-AAS). Analyzing 124 forensic postmortem samples over nearly three years, the study found both methods to be comparable and satisfactory across a wide COHb saturation range (5–85%), with CO-oximetry demonstrating better precision and accuracy and requiring less sample preparation. Minor discrepancies were observed, particularly in samples with high COHb or methemoglobin levels, and dilution or sample quality factors may influence results. The study concludes that CO-oximetry alone is suitable for routine forensic COHb screening and confirmation, with HS-GC--FID-AAS reserved for cases unsuitable for oximetry, thereby fulfilling forensic toxicology guidelines for independent confirmation.