Quantification of phytic acid in baby foods by derivatization with (trimethylsilyl)diazomethane and liquid chromatography–mass spectrometry analysis

Rationale Phytic acid (PA) is both a naturally occurring nutrient and a widely used food additive for conferring antioxidant properties to food. PA can be found in baby foods and it is essential to monitor PA content due to its anti-nutritional properties when present in excess. Current methods for determining PA content are unsatisfactory because interference from inositol phosphates and inorganic phosphates complicates PA quantification. Methods Baby foods were extracted using aqueous HCl, and the extractant was subjected to derivatization with (trimethylsilyl)diazomethane after de-metalation using a cation exchange resin. The PA derivative was quantified using liquid chromatography–mass spectrometry (LC/MS/MS) with a multi-response monitoring mode ( m / z 829 to 451). Results The linearity of the developed analytical method ranged from 10 to 1000 ng/mL for PA with R 2 > 0.999. Reasonable reproducibility was obtained with an intraday relative standard deviation (RSD; N = 5) of 4.5% and an interday RSD ( N = 5) of 5.7% at a concentration of 10 ng/mL. The developed method was successfully applied to determine PA content in various baby foods, with PA recovery between 90.6% and 119.8%. Conclusions A robust and sensitive method for the determination of PA in baby foods has been developed by methyl esterification with (trimethylsilyl)diazomethane and using LC/MS/MS analysis. The established method showed good anti-interference and precision, and it has been applied for the determination of PA in various baby foods.