Spectrophotometric determination of cyanide with pyridine and 4,4′-diaminostilbene-2,2′-disulphonic acid

Abstract

The use of 4,4′-diaminostilbene-2,2′-disulphonic acid (amsonic acid) as an alternative coupling agent to barbituric acid in the determination of cyanide is proposed. Amsonic acid possesses cost and availability advantages, and the stability of the pyridine-amsonic acid reagent is greater than that of pyridine-barbituric acid (17 d versus 24 h). The method can be applied at a wide range of cyanide concentrations, from 0.01 to 0.10 µg ml^–1 at 490 nm and from 0.10 to 0.60 µg ml^–1 at 545 nm. The detection limit is about the same order of magnitude as the standard method.