Control of Konzo and Kits to Determine Cassava Cyanide and Urinary Thiocyanate

Kits available to measure total cyanide in cassava roots and flour and urinary thiocyanate

In 1995 we developed a new quantitative method of determination of cyanide, based on the well-known qualitative picrate paper test for cyanide. The method can be used as a simple field test with a colour chart with 10 shades of colour from 0-800 mg HCN equivalents / kg fresh weight = ppm, and/or quantitatively by elution of the colour from the paper in water and measurement of the absorbance at 510 nm in a spectrophotometer (Egan et al., 1998; Bradbury et al., 1999). The quantitative method was compared over a wide range of cyanogenic plants and foods with the acid hydrolysis method, and found to be just as accurate (Haque and Bradbury, 2002). We have increased tenfold the sensitivity of the picrate method by using a smaller picrate paper and elution volume and use of micro cells in the spectrophotometer (Bradbury, 2009).

Kits A and B 2 have been developed for determination of total cyanide in cassava roots and cassava products and each kit allows 100 analyses to be made. The stepwise procedures to be followed for use of these kits are available as protocol A and protocol B2. Subsequently, kits have been developed to allow analysis of cyanogenic leaves (kit E), bamboo shoots (kit F) and flax seed meal (Kit G). These kits are available free of charge to health workers and agriculturalists in developing countries.

Ingested cyanide is converted to thiocyanate in the body and removed in the urine, thus a urinary thiocyanate determination gives a measure of cyanide intake over the preceding days. We have developed a picrate method (Haque and Bradbury, 1999b) for determination of thiocyanate in urine, which was successfully trialled in Mozambique in 1999 (Ernesto et al. 2002a). The method is available as kit D 1 and a stepwise procedure Protocol D1 is available, for the use of this kit.

The Australian Centre for International Agricultural Research (ACIAR) funded the research and development of kits A to G and also supply of the kits, free of charge to agriculturalists and health workers in developing countries. This funding ceased in 2004 but the free offer is still available. Kits A, B2, D1, E, F and G may also be purchased by workers in developed countries for Australian $700. Nearly 600 free and 500+ purchased kits have now been supplied to workers in over 30 countries.

Kit A: Determination of total cyanide in cassava roots. Protocol A (PDF File)
Kit B 2: Determination of total cyanide in cassava products (flour, gari, etc) Protocol B2 (PDF File)
Kit D 1: Determination of thiocyanate in urine. Protocol D1 (PDF File)
Kit E: Determination of total cyanide in leaves. Protocol E (PDF File)
Kit F: Determination of total cyanide in bamboo shoots. Protocol F (PDF File)
Kit G: Determination of total cyanide in flax seed (linseed). Protocol G (PDF File)