Indirect determination of phytic acid in urine

An indirect spectrophotometric method for the determination of phytic acid in human urine based on the reduction of molybdophosphate to molybdenum blue and its extraction as an ion pair with Adogen 464 is described. The method requires a clean-up of the sample with activated carbon, a separation of phytic acid from other components by column anion exchange chromatography: and its hydrolysis by microwave treatment. The calibration graph was linear over the range 0.03-0.30 mg l(-1) PO43- (referred to the aqueous phase), its slope being 1.66 l mg(-1). The relative standard deviation for a sample containing 6.4 mg l(-1) phytic acid was 0.7% (n=5). Found concentrations in urine were in the range 6.4-0.5 mg l(-1) phytic acid. (C) 1998 Elsevier Science B.V. All rights reserved.