Volume 41, Issue 3 (May 1996)
Stability and Spontaneous Production of Blood Cyanide During Heating
To investigate the effects of heat on blood cyanide concentrations, in vitro experiments were performed using a headspace gas chromatographic method. Cyanide concentrations were determined for solutions of human hemoglobin (Hb) at neutrality, and for blood which was sealed in a vial and incubated at 25, 50, 63, 75 and 90°C for 1 h. Spontaneous cyanide production was also measured. Nearly all of the added cyanide was recovered in both the Hb and for blood samples which were heated below 63°C. Cyanide recovery in Hb decreased in a temperature-dependent manner at temperatures above 75°C, and more than half of the recovered cyanide was found to be in the free form. In contrast, cyanide in blood disappeared more rapidly, and a major portion of it existed in the bound form. Cyanide concentrations in Hb solutions which were heated at 90°C dropped in the two phases; a rapid initial phase, followed by a slower process. Spontaneous cyanide production was observed at temperatures above 50°C for Hb and above 63°C for blood. Under optimal conditions (75°C heating), about 0.2 mmol of cyanide was produced per mol heme of Hb.