An evaluation and modification of a microdiffusion method for the emergency determination of blood cyanide.

Data are presented to indicate the recovery one can expect with different diffusion times in the microdiffusion procedure for the determination of cyanide using Conway cells. Using a predetermined recovery factor, a diffusion time of 10 min is recommended for emergency situations. In the use of the pyridine-barbituric acid reagent for color development, it was found that the reagents could be added as rapidly as is manually possible and that while the color complex begins to fade as soon as developed, the error after 4 to 10 min ranges from 3 to 9%.