Low-Level Speciation of Cyanide in Waters

Frontier Geosciences, Inc., proposes to develop a novel method for the speciation of a wide variety of different covalent and complex cyanides in waters, based on the coupling of a chromatographic separation to the most sensitive and selective cyanide detector that currently is available commercially. This type of method development specifically is requested by the U.S. Environmental Protection Agency (EPA) because the techniques currently available for cyanide speciation do not meet all the requirements of the EPA and the affected industries. Operationally defined techniques can only separate free from complexed cyanide, and generally are susceptible to matrix interferences, especially to false positive results. Conversely, the few available direct speciation techniques that separate different cyanide species chromatographically often use detectors that lack either sensitivity or specificity, resulting in limited applicability of the method (only in strongly contaminated environments) or in the lack of positive identification of a signal as one defined cyanide species. Frontier Geosciences, Inc., collaborates closely with the mining and petroleum industries and their regulatory counterparts in the areas of metal(loid) analysis, speciation, and geochemistry, and has experienced a very strong demand and need for direct, sensitive, specific, and accurate cyanide determination and speciation during the last few years. The anticipated solution for the problem investigated in this proposal consists of an ion chromatographic (IC) separation of the anionic cyanide species, coupled to an online UV-assisted wet chemical derivatization step that breaks down all cyanide species to free CN , which then is detected by a flow injection-gas diffusion-amperometric detection (FIGDAD) system. The final method would permit the separation and quantification of at least nine different cyanide species with detection limits of 1 ¿g/L per species. The Phase I objectives are to: (1) couple IC to FIGDAD and demonstrate a detection limit of 1 ¿g/L for CN- ; (2) develop the separation of nine relevant cyanide species; (3) demonstrate the feasibility of online UV-photolytic breakdown for [Fe(CN)6]3- and [Fe(CN)6]4- ; and (4) demonstrate feasibility of the method in real-world water samples and in alkaline leachates from cyanide-contaminated soils/sediments.