| Abstract: | Abstract An automated benzidine-pyridine method for the analysis of total cyanide is described. Cyanides are converted to cyanogen bromide by the reaction with bromine water. Cyanogen bromide reacts with benzidine in a dilute pyridine medium to form an intense red color directly proportional to the cyanide concentration. Cyanide often is found complexed with metals. Complex iron cyanides such as ferrocyanide or ferricyanide are difficult to decompose, but the conversion is hastened with mercuric chloride and magnesium chloride in a modified Serfass distillation.1 Hydrogen cyanide is readily formed and absorbed in sodium hydroxide. |
