Analyzing Cyanide by Ion Chromatography

Ideal method for testing cyanide and metal cyanides in drinking water

Metal cyanide complexes are negatively charged ionic complexes consisting of one or more cyanide ions bound to a single transition metal cation. Metal cyanides are an environmental concern because they can dissociate to release the toxic substance HCN into water. Cyanide also occurs naturally in foods such as bamboo shoots and almonds, and it is naturally generated by microorganisms. Cyanide is used in industries like plating and mining, and can be released into the air from burning coal and plastics.

Cyanide analysis

Colorimetric and spectrophotometric methods have traditionally been used for cyanide detection and quantitation. However, these methods require distillation and can have many interferences. Ion chromatography methods for cyanide can resolve each individual metal cyanide complex into a discrete chromatographic peak, allowing a precise differentiation of complexes of lesser toxicity from those of greater toxicity.

Regulatory information

The U.S. government classifies cyanide as a regulated inorganic contaminant in drinking water. The following regulatory bodies have established guidelines around cyanide.

  • EPA: Specifies a Maximum Contaminant Level (MCL) in drinking and surface water of 200μg/L of free cyanide. In wastewater, there is a limit of 5.2μg/L total cyanide continuous discharge from publicly owned treatment works, 22μg/L maximum discharges into fresh water, and 1μg/L into salt water.
  • FDA: In bottled water, an MCL of 0.2mg/L.
  • WHO: Specifies an MCL of 0.07mg/L in drinking water.

Example application notes