Small-Scale Ultrasound-Assisted Extraction of Phenolics from Pomegranate Peels and Their Application as a Natural Reagent for the Colorimetric Assay of Iron

Abstract

An environmentally friendly field-portable approach based on small-scale ultrasound-assisted extraction and micro-volume colorimetry was proposed for the determination of iron using natural reagent extracts from pomegranate peels. Ultrasound technology was utilized for the extraction of pomegranate peels in acetate buffer pH 5.5. Sonication parameters influencing the extraction process of natural reagents from pomegranate peel were investigated, including the type of solvent, mass/volume ratio of solvent, sonication time, temperature, and power. The efficiency of the ultrasound-assisted procedure for the extraction of iron from pharmaceutical formulations was evaluated by comparing to their label value and the reference method for pharmaceutical formulations. A linear calibration graph ranging from 1.0 to 10.0 mg L−1 Fe(III) was obtained from micro-volume colorimetric determination (at 530 nm) with limits of detection and quantification of 0.31 and 0.78 mg L−1, respectively. The reproducibility for 3.0 mg L−1 Fe(III) was 3.8% as the relative standard deviation. This developed system was successfully applied to determine the iron content in pharmaceutical formulations and the results agreed well with those obtained by a reference method. Good recoveries between 97 and 105% were obtained.