Synchronous Fluorescence Determination of Phytic Acid in Foodstuffs and Urine Based on Replacement Reaction

Introduction - Phytic acid is a ubiquitous and abundant natural component in many plant seeds, fruits and vegetables. Its biological and pharmaceutical functions are still controversial. The examination on the level of phytic acid in foodstuffs and urine can provide valuable information for its dietary intake and metabolism. Objective - To develop a sensitive and reliable synchronous fluorescence protocol for determination of phytic acid in selected foodstuffs and human urine. Methodology - Phytic acid efficiently catches Cu2+ ion in previously prepared Cu-II-2,2'-bipyridine complex in aqueous solution, releasing the fluorescent 2,2'-bipyridine molecule and recovering synchronous fluorescence. The recovered fluorescence is proportional to the added phytic acid, by which the levels of phytic acid in the selected foodstuffs and human urine are quantified. Results - A calibration curve with a regression equation of I-f = 37.745 + 39.245c (R-2 > 0.9988) showed good linearity over the range 0.18-17.50 mg/L phytic acid. The relative standard deviation at 95% confidence degree was less than 2.04% (n = 5), indicating that the procedures are reproducible. The detection and quantification limit of phytic acid were estimated to be 0.12 and 0.18 mg/L, respectively. By the proposed method, phytic acid in the selected foodstuffs and urine was determined to be 3.25-16.76 and 0.43-1.21 mg/L with recoveries of 96.8%-105.6% and 95.1%-104.2%, respectively. The results are in good agreement with those obtained by the reported HPLC technique. Conclusion - The developed method is sensitive, reliable and economical, which permits its practical application in quantitative analyses of trace phytic acid in foodstuffs and urine. Copyright (c) 2010 John Wiley & Sons, Ltd.