Selective spectrophotometric determination of canavanine
The optimisation of the analytical conditions for the spectrophotometric determination of canavanine (a non-protein amino acid that is important in animal nutrition) with pentacyanoaminoferrate-(II) and -(III)(PCAF) is described. The most influential parameters, e.g., reagent preparation, oxidant, pH, buffer composition, interferences, etc., were studied. The best results were obtained with freshly synthesised PCAF whose aqueous solutions were either kept in the dark or activated with UV light, with pH 7 phosphate buffer, by the addition of potassium persulphate solution (1%) and by measurement at 520 nm. The procedure was applied to the determination of canavanine in an acidic extract of lentil vetch seeds, a legume that is widely used in animal feed.