Simple and Sensitive Spectrophotometric Method for Phytic Acid Determination in Grains

Phytic acid (PA) is the main way to store phosphorus in plants, representing about 60-82 % of the total content of phosphorus. The PA determination is still an analytical dare due to low chemical reactivity of this compound. The present work developed a simple and sensitive spectrophotometric method for phytic acid determination on a basis of a colored complex formation between glyoxal bis(2-hydroxianiline) (GBHA) and calcium ions in an alkaline medium (pH 12.5), inhibited by phytic acid presence. The selectivity of the method was evaluated for 15 possible interferences among anions and cations. The main figures of merit from the method in aqueous solution and optimized conditions presented a linear range from 1.0 to 12.5 mg L-1 (n = 8) for analytical curve A = -0.037C (PA) + 0.72 (r = 0.9981), limit of detection (LOD) equivalent to 0.33 mg L-1, and relative standard deviation (RSD) less than 2.7 %. The proposed method was applied to determine phytic acid in different grain bran/flour samples, the results when compared with reference procedure (Wade method) had no significant difference (significant level of 95 %). Additionally, to explore more applications, the proposed method was employed to determine phytic acid concentration in cream for skin whitening, with recovering of more than 86 %. Therefore, according to the results, the method was versatile with good precision, accuracy, and detection limit similar or better than other works described in the literature.