title: Simple spectrophotometric method for determination of phosphine residues in wheat.
abstract: A method has been developed for determination of phosphine residues in wheat, based on the reaction of phosphine with silver nitrate in aqueous solution to form an egg-yellow chromophore with an absorption maximum at 400 nm. At this wavelength, there is a linear relationship between absorbance and concentration of phosphine in the range 10-100 ng/mL. Phosphine-fumigated wheat is soaked in a known volume of AgNO3 solution, and the absorbance of the filtrate is read against a blank at 400 nm. The method is sensitive, with lower detection and estimation limits of 0.008 and 0.01 micrograms PH3, respectively. Recovery of added phosphine from a closed system was 85-100%. Accuracy for this method has been compared with that for the gas chromatographic method.
mesh_terms: D010573:Pesticide Residues / Q000032:analysis*; D010720:Phosphines / Q000032:analysis*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D014908:Triticum / Q000032:analysis*
chemical_list: D010573:Pesticide Residues; D010720:Phosphines