CYANIDE TEST
Cassava roots and leaves should not be consume raw because it contain two cyanogenic glucosides (Linamarin and Lotaustralin), these are decomposed by Linamarase a naturally occurring enzyme in cassava liberating Hydrogen cyanide. Excess cyanide residue from improper preparation of cassava products is known to cause goiters, ataxia, calcific pacreatitis and acute cyanide intoxication cause vomiting, collapse and in some cases even death within one or two hours. Patients of cyanide intoxication can be treated easily by injecting thiosulphate (thiosulphate react with cyanide to form thiocyanate)
AIM: To determine the presence of cyanide in cassava products
APPARATUS: 500ml Sample bottle, Spatula, Stirrer
REAGENT: Chloroform, distilled water, Picric paper
PRINCIPLE: The reaction of chloroform with cyanogenic glucosides leads to release of hydrogen cyanide which turns the picric paper reddish-brown
PROCEDURE:
Weigh 50g of the sample into the 500ml flour ( cassava flour (Garri))
Add 20ml of distilled water and stir
Add 2ml of Chloroform
Insert the Picric paper immediately with one part of it suspended on the sample bottle mouth and cover
Keep in a dark room for 8 hours ( or overnight)
Reddish colouration of the Picric paper indicates the presence of Hydrogen Cyanide
Dip picric paper into 10ml distilled water for 30 minutes and take absorbance of the resulting solution making water your blank at 510nm
Cyanide concentration = absorbance* 396
Limit: 10ppm (part per million)
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