Ultrasensitive methods are described for the detection and determination of cyanide-containing organic compounds and of various metal ions. The methods are based either on the hydrolysis of the organic compounds to give cyanide ion, which then catalyzes the reduction of o-dinitrobenzene via formation of the cyanohydrin anion of p-nitrobenzaldehyde, or on the inhibition of this catalytic reaction by silver-(I), mercury(II), copper(II), cobalt(II), nickel(II), zinc(II) and cadmium(II) which form cyanide complexes. By these methods, tetracyanoethylene, p-chlorobenzylidine malononitrile, or benzoyl cyanide (0.1-10 μg/ml) may be determined with a deviation of about 2%, and Ag(i). Hg(II) (0.02-0.2 μg/ml), Cu(II) (0.003-0.030 μg/ml), Co(II) (0.06-0.40 μg/ml) and Ni(II), Zn(II) and Cd(II) (1-10 μg/ml) can be determined with a deviation of about 3%. © 1968.
