High-performance liquid chromatographic method for the determination of phytate

An improved method for the determination of phytate ( myo-inositol 1,2,3,5 4,6 hexakis (dihydrogen phosphate)) in plants is described. Phytate is extracted with 0.5 n HCl, purified and concentrated on an AG 1-X8 anion-exchange resin, taken to dryness in a vacuum desiccator, and analyzed by reverse-phase liquid chromatography on a μBondapak C 18 column. The refractive index peak due to phytate is well separated from a minor salt peak, and the area under the peak is linearly proportional to the phytate concentration over a wide range. Unlike most conventional methods involving precipitation by FeCl 3, the simpler and more reliable high-performance liquid chromatographic (hplc) assay avoids the numerous assumptions inherent in the iron precipitation, and accuracy is independent of the phytate content. As little as 0.003% phytate in plants may be quantitated with a coefficient of variation of less than 5%. When several cereal brans are analyzed by both the present method and a colorimetric method, excellent agreement is obtained between the values for phytate content at concentrations greater than 0.2%; lower concentrations can be detected only by the hplc method.