Results are expressed as ppm (mg/L) cyanide. Measurements are made against a color comparator. The CHEMets® visual colorimetric test kit develops a blue-purple color in direct proportion to the free cyanide concentration. For total cyanide analysis, distillation of the sample is required.ĬHEMetrics offers both visual and instrumental test kits employing the Isonicotinic-Barbituric Acid Method for the measurement of free cyanide in water. Sample pretreatment to remove hydrogen sulfide is recommended. It is common to monitor effluents and surface water supplies for cyanide to ensure that it is not entering natural waters or potential drinking water sources.ĬHEMetrics’ free cyanide water test kits are applicable for monitoring effluents and surface water supplies. Due to the potential for both short-term and long-term health effects to humans, the Maximum Contaminant Level for free cyanide in drinking water is 0.2 mg/L.
However, due to its acute toxicity to aquatic life, discharges from industrial and municipal wastewater facilities are regulated through permitting processes, necessitating routine effluent monitoring. Total cyanide is the sum of all inorganic forms of cyanide that dissociate into free cyanide when refluxed under strongly acidic conditions.Ĭyanide can be safely removed from water by alkaline chlorination. Free cyanide is defined as the sum of molecular hydrogen cyanide (HCN) and cyanide ion (CN –). Cyanide is often found in effluent from electroplating and metal cleaning operations, coke ovens, steel manufacturing facilities, gas scrubbers, and polymer production. It readily reacts with transition metals which makes it useful for industrial purposes but also makes it a toxic compound.
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