INDIRECT DETERMINATION OF CYANIDE BY ATOMIC-ABSORPTION SPECTROMETRY

Two methods for determination of cyanide by atomic absorption spectrom etry (AAS) are developed. Both methods are based on the formation of a n ion association compound between a metal complex, (Ag(CN)(2)(-) or C u(CN)(3)(2-)), and a quaternary ammonium ion (benzyldimethylhexadecyla mmonium ion). The ion association compound is extracted into isomethyl butylketone (IBMK) and the metal is determined by AAS directly in extr act. The method based on the formation of silver cyanide complex provi des a reproducibility of 2.5%, a recovery of 99% and a detection limit of 1.7 mu g/L while the method based on the formation of copper compl ex gives a reproducibility of 6%, a recovery of 93% and a detection li mit of 0.6 mu g/L. Several foreign ions were studied; the method based on the formation of Ag(CN)(2)(-) presents minor interferences.