Selective Determination of Free Cyanide in Environmental Water Matrices by Ion Chromatography with Suppressed Conductivity Detection

The study was aimed at developing suitable chromatographic conditions and pretreatment methods for reliable trace analysis of cyanide in drinking water and seawater. Separation of CN^- (as CNO^-), F^-, Cl^-, Br^-, and was carried on a Dionex IonPac AS20 column. Two different methods were developed for different samples. LOD and LOQ values were 7.2 g L^-1 and 24.0 g L^-1 for Method I and were 15.4 g L^-1 and 51.3 g L^-1 for Method II, respectively. Our results did not indicate the presence of cyanide in drinking water samples commercially supplied from Istanbul markets. By the addition of 250, 500, and 1000 g L^-1 to drinking water, cyanide recoveries were found 100.1%, 104.5%, and 106.9%, respectively, by employing Method I. Method II was applied to an artificial and real seawater sample obtained from the Marmara Sea, Istanbul, where a 50 g L^-1 cyanide spike gave a recovery of 100.1%. Interferences from excessive amounts of salts in seawater were removed by using strongly acidic cation-exchange resin and melamine-formaldehyde resin. The proposed pre-Treatment Method (II) and chromatographic conditions provided low LODs for cyanide in seawater (well below acute toxicity limits), as dilution errors and matrix effects were eliminated.