RAPID SCREENING ASSAY OF CYANIDE CONTENT OF CASSAVA

A rapid, inexpensive screening assay was developed in order to measure the cyanide content of cassava (Manihot esculenta Crantz) tubers. A small disc of parenchyma tissue cut with a cork borer or alternatively grated tissue was placed in a stoppered glass tube and the hydrogen cyanide liberated produced a blue colour on a filter paper previously spotted with a drop of tetra-base 14,4'-methylenebis-(N,N-dimethylaniline)] and cupric acetate. The intensity of the blue colour which developed within one hour was rated visually on a graded scale from 0 to 5. The correlation coefficient between samples accurately analysed for total cyanide and also tested using the rapid assay was 0.77.