Rapid Determination of Cyanide and Azide in Beverages by Microdiffusion Spectrophotometric Method

A rapid screening method was developed for the determination of the toxic volatile anions, cyanide and azide, in beverages. This method consisted of a microdiffusion extraction combined with spectrophotometry using the König cyanide reaction and ferric azide complex formation in conjugation with cerium azide oxido-reduction. The time required to achieve full recovery in the extraction of hydrogen cyanide and hydrazoic acid from samples was considerably shortened by increasing the diffusion temperature from 25°C to 40°C. The time required to achieve saturated color development in the König cyanide reaction was also shortened by increasing incubation temperature to 40°C. The interference in both azide color reactions was examined for volatile compounds. Cyanide interfered only in the case of ferric azide complex formation. Sulfide, sulfate, nitrite, and acetic acid interfered in both the color reactions. The established method gave a detection limit of 6µM for cyanide and 0.5mM for azide, and it required only 1 h to determine both anions. Cyanide and azide disappeared by evaporation from beverages during 25°C storage under open conditions in a pH-dependent manner as a function of their respective pKa values of 9.2 and 4.6.