Determination of cyanide through its reaction with gelatin-stabilised gold sol in air

Abstract

A highly specific spectrophotometric method for the determination of cyanide is described, based on the dissolution of a pink gold sol (λ_max. 530 nm) in the presence of air. The coloured gold sol becomes colourless at the end-point. Under the experimental conditions, the minimum amount of cyanide that can be determined is 0.16 µg ml^–1. The relative standard deviation and confidence limit (95%) for 4.24 µg of cyanide (40 replicates) are 0.51% and 4.239 ± 0.007, respectively. The method shows a remarkable freedom from interferences and it is suitable for the determination of total cyanide in industrial and biological samples without preliminary distillation.