Determination of phytic acid in wheat and wheat products by reverse phase high performance liquid chromatography

Abstract

A sensitive method for accurate determination of phytic acid in food samples is described. The proposed procedure involves high performance liquid chromatography (HPLC) and UV–vis detection. The method was based on metal replacement reaction of phytic acid from coloured complex (iron(III)–thiocyanate), separation and monitoring any decrease in concentration of coloured complex. The retention time for the monitored iron(III)–thiocyanate peak was achieved in less then 3 min in Gaussian shape. The proposed HPLC/UV–vis procedure shows good linearity over the concentration range of 10–125 μg ml −1 with correlation coefficient value of 0.997. The procedure is reproducible and accurate, illustrating a standard deviation between 0.72 and 1.20 μg ml −1 ( n = 10, for 50 μg ml −1) and relative standard deviation between 1.40 and 2.98% ( n = 10, for 50 μg ml −1) within and between days for reproducibility and absolute error ranging between 0.16 and 1.54% ( n = 10, for 100 μg ml −1) within and between days for accuracy, respectively. Detection limit was estimated as 0.5 μg ml −1 which is suitable for analysis of foodstuffs and plant materials in that phytic acid usually presents within 2.5–50 μg ml −1 range. The procedure was then applied to determination of phytic acid in wheat and wheat products. The content of the phytic acid in the samples was calculated by using the calibration curve obtained from the standard solution of phytic acid and iron(III)–thiocyanate solutions containing 100 μg ml −1 iron(III) ion.