Application of portable oximeter for the determination of methemoglobin in forensic practice

N. Tanaka, K. Ameno , M. Jamal, A.Ito , N. Miyatake , M. Kumihashi, S. Kimura, K. Tsutsui, H. Kinoshita,

Abstract: The concentration of methemoglobin (Met-Hb) in blood provides useful information in cases of exposure to oxidizing agents such as nitrates, nitrites or chlorates. In the present study, we determined Met-Hb concentrations in blood samples using a portable AVOX 4000 oximeter (AVOX) and compared the results to the conventional spectrophotometric method. There was good correlation between the values obtained by oximeter and those obtained by the conventional method, in the range of 0-70% Met-Hb. Because Met-Hb is unstable, it is important to analyze it soon after sampling. The concentrations of Met-Hb in samples stored at 4°C gradually decreased over time. We applied forensic sample obtained from fire-related deaths, and carboxyhemoglobin (CO-Hb) was also determined simultaneously by AVOX. AVOX is a new tool that is suitable for Met-Hb determination because of its easy handling and it requires a smaller sample size than the conventional method.
Keywords: oximeter, methemoglobin, stability, fire-related death.