In 1995 we developed a new quantitative method of determination of cyanide, based on the well-known qualitative picrate paper test for cyanide. This has now been translated into 16 languages. 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 (see Publications Nos. 17 and 19). 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 (see Publications No. 15). Linamarin and linamase were isolated for use in the kits (see Publications Nos. 23 and 24). 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 (see Publications No. 10).
Kits A and B2 were developed for determination of total cyanide in cassava roots and cassava products and each kit allows 100 analyses to be made. Subsequently, kits were developed to allow analysis of cyanogenic leaves (Kit E), bamboo shoots (Kit F) and flax seed meal (Kit G).
Ingested cyanide is converted to thiocyanate in the body and is removed in the urine, thus a urinary thiocyanate determination gives a measure of cyanide intake over the preceding days. Kit D1 was developed for the determination of thiocyanate in urine (see Publications No. 18), which was successfully trialled in Mozambique in 1999 (see Publications No. 16).
Kits and protocols are available. Read more about our Konzo kits.
A coloured poster which shows how to use the wetting method to remove cyanide from cassava flour was originally produced by Dr Dulce Nhassico in Portuguese. This was translated into English and other languages. It has since been modified twice to include cyanide poisoning and also another treatment option of standing for two hours in the sun to remove hydrogen cyanide from the wet flour. The text has been translated into many different languages (we wish to thank our many translators), and the words have been placed into the pictures by Mr Ian Denton. These laminated posters in 16 languages (a few have not been updated with the 2hr in the sun option) are available free of charge to be distributed in rural areas, particularly those where konzo and cyanide poisoning occur.
Poster English Gari
Poster Portuguese (Brochure)
Those marked * have not been updated for the 2hr in the sun modification.