The determination of cyanide in water and biological tissues by methemoglobin

Abstract

The authors developed a simple and sensitive method for the determination of cyanide using spectrophotometry to measure changes caused by cyanide in the absorption spectra of methemoglobin. Met-hemes in the hemoglobin molecules react with cyanide rapidly to form a cyanomethemoglobin complex, even at low concentrations of cyanide, in a stoichiometric manner. After adding cyanide, the absorption spectra of methemoglobin changed with a typical decrease in absorbance at 630 nm, and an increase in absorbance at 540 nm. These changes were closely correlated with the concentrations of cyanide ion. From the results, it was shown that 0.2 μg/ml of cyanide ion in water and 0.4 μg/ml in biological tissues can be detected by this method. The method may be useful for the convenient and sensitive detection of cyanide in waste water and biological tissues and fluids.