Modified picrate method for determination of cyanide in blood.

Cyanide (CN-) is widely distributed in the ecosystem and has been associated with toxic effects in humans and animals. Most outbreaks of CNֿ poisoning in animals result from ingestion of plants containing cyanogenic glycosides. Various analytical techniques for estimating cyanide in blood are available. A simple picrate method was developed to determine blood CN- in goats. This assay is a modification of commonly available methods using picrate paper and those using Conway diffusion cells. Cyanide in blood was measured during and after IV administration of KCN at 0.6 mg/min for 1 h. Blood CN- levels in rabbits were determined after oral administration of KCN for 10, 20, 30 and 40 days. The CN- concentration in blood of goats was time-dependent and continued rising during infusion followed by gradual decline after infusion stopped. A calibration curve set by dissolving various concentrations of KCN in distilled water showed a linear relationship between CN- concentration and absorbance (R=0.995) ranging from 0.3-120 mg CN-/L. Blood CN- levels in rabbits showed time-dependent increase with maximum concentration (1.34 mg/L) at 40 days. This is a simple and inexpensive tool for the determination of blood CN- in the laboratory and under field conditions as well.