This protocol describes how to analyse total cyanide (HCN) levels in fresh cassava roots using the picrate paper method. The method gives the potential cyanide content of cassava roots on a fresh weight basis. The picrate paper method for root cyanide determination relies on endogenous enzymes to breakdown the cyanogenic glucosides (linamarine) in fresh cassava root samples. The hydrogen cyanide liberated in the process reacts with picrate papers that have a colour pigment which darkens with released cyanide. The variations in the darkening of picrate papers is then used to measure the amount of hydrogen cyanide released from fresh cassava root samples. The picrate paper method is argued to not be a very reliable method for cassava cyanide determination. However, if you are going to have to work far from a laboratory where you cannot perform another preferred method, then the picrate paper method is your best option as you may not be able to avoid root deterioration and cyanide loss during transportation of cassava root samples. The key to using this method is focus, precision and timeliness. If these three are maintained throughout the analysis then chances of introducing errors are reduced making the obtained results more comparable with other cyanide determination methods.This protocol has been already well outlined by Dr J.H. Bradbury and his team, so please refer to their document (see the attached document below). A kit for cyanide analysis in cassava roots called PROTOCOL A: DETERMINATION OF TOTAL CYANIDE IN CASSAVA ROOTS, has also been designed by them. This protocol describes how the Protocol A kit can be used to determine cyanide in cassava roots. This protocol is not a replacement of the original protocol. Some of the contents of this protocol have however been directly copied from the original protocol; they are indicated in bold text. This protocol however contains additional insights from things encountered during the use of the kit; this information is in normal text. In addition to this, this protocol includes insights that Dr Bradbury shared to help troubleshoot a few unforeseen issues; these insights are in italics.