Cyanogens are cyanogenic glucosides and are widespread in the plant kingdom in trace amounts. These glucosides release hydrogen cyanide by an endogenous enzymic reaction. Relatively high concentrations are found in certain grasses, root crops and fruit kernels. Young sorghum plants particularly ratoon crop, contain high amounts of cyanogens and bring deleterious effects on cattle.
Hydrocyanic acid which is evolved from the sample, forms a red colored compound with sodium picrate and the intensity is measured at 625nm.
» Whatman No.1 Filter Paper: Cut filter paper into strips 10-12cm long and 0.5cm wide, and saturate them with alkaline picrate solution.
» Alkaline picrate solution: Dissolve 25g sodium carbonate and 5g picric acid in one liter of water.
» Standard Hydrogen Cyanide Solution: Dissolve 0.241g of KCN/liter of water. This gives a solution containing 100mg hydrogen cyanide/mL.
Calculate the hydrogen cyanide content of the sample from the standard graph.
1. Hogg, P G and Ahlgren, H L (1942) J Ame Soc Agron 34 199.
2. Indira, P and Sinha, S K (1969) Indian J agric Sci 39 1021.
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