Quantitative determination of phytate in the presence of high inorganic phosphate

Abstract

The review on the determination of phytate and inositol phosphates by Oberleas (1) indicates that most methods for the determination of phytate are derived from the method of Heubner and Stadler (2). This method is based on the principle that ferric ion forms a stable complex with phytate in dilute acid solution and is the only phosphate compound, at least in significant concentration in nature, with this property. However, the phytate values were high when we applied the procedure of Oberleas (3) to samples with high inorganic phosphate content such as rat feces or semipurified rat diets. This appeared to be a result of inorganic phosphate coprecipitating with ferric phytate. As a preliminary step to study phytate balance in rats, a modified procedure of the Oberleas (3) method was developed that appears to free the ferric phytate precipitate of inorganic phosphate. The procedure and its efficiency are reported in this communication.