Multicomponent Spectroscopic Assay for Hemoglobin and Ferrihemoglobin Species in Methemoglobin Treatment of Cyanide Poisoning

Monitoring the concentrations of various hemoglobin and ferrihemoglobin species and their cyanide complexes is important in the study of the efficacy of methemoglobin-forming agents for the treatment of cyanide toxicity. In this study, the visible absorption spectra of three hemoglobin intermediates were experimentally determined and compared with computer-generated spectra. The data supported the assumption that the molar absorptivities of the intermediates are equivalent to the combined absorptivities of the component subunits. A multicomponent Fourier transform (FT)-aided full spectrum quantitation system (FSQ®) to simultaneously measure hemoglobin (Hb), hemimethemoglobin (hemiMetHb), and the cyanide complex dicyanohemimethemoglobln (dicyhemiMetHb) was also evaluated. It was found that FSQ had satisfactory accuracy and precision to quantitate hemiMetHb and dicyhemiMetHb at concentrations from 2 to 20% of the total Hb, a range commonly encountered in the treatment of cyanide poisoning using methemoglobin-forming agents. The simplicity and rapid throughput of the method make it suitable for clinical evaluation studies and form the basis for the design of a portable instrument for field analysis of these species.