Cyanide is a carbon-nitrogen chemical unit which combines with many organic and inorganic compounds. It is an extremely toxic substance that is produced naturally and artificially. Cyanides are generally not persistent when released to water or soil, and are not likely to accumulate in aquatic life. But high levels of cyanides can cause rapid toxicity among aquatic life. One of the easiest and cheapest method available for the determination of cyanide concentration is the cyanide-selective electrode method.