Determination of low environmental free cyanide concentrations in freshwaters

Cyanide compounds are naturally emitted into the environment in low levels by degradation processes or emitted from anthropogenic sources. In surface water, complex cyanide compounds as well as 'free cyanide' are present. The latter term covers hydrogen cyanide and cyanide compounds which easily liberate hydrogen cyanide under slightly acidic conditions. Especially free cyanide may cause adverse effects in the environment. To exclude negative impacts on freshwater systems, in the context of the European Water Framework Directive (WFD), preventive regulatory activities for free cyanide are currently under discussion. However, established analytical methods for quantification of free cyanide only obtain limits of quantification (LOQs) in the range of 1 μg