How to carry out CYANIDE TEST on Cassava Products - BIOSCIENCE EDUCATION

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Sunday 4 April 2021

How to carry out CYANIDE TEST on Cassava Products


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 


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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