Extraction of endocrine disrupting phenols with iron-ferric oxide core-shell nanowires on graphene oxide nanosheets, followed by their determination by HPLC

We describe a novel magnetic nanosorbent that consists of nanowires consisting of a core of metallic iron and an iron (III) oxide shell. These nanowires were then deposited on graphene oxide to form a composite of the type Fe@Fe2O3/GO. Specifically, the magnetic composite is formed via electrostatic interaction between negatively charged GO nanosheets and positively charged Fe@Fe2O3 nanowires in aqueous solution. The material was successfully applied to the extraction of the endocrine-disrupting phenols bisphenol A, triclosan and 2,4-dichlorophenol from water samples. Compared to neat graphene oxide, the composite material exhibits improved properties in terms of microextraction where both the hydrophilic graphene oxide and the Fe@Fe2O3 nanowires participate in the adsorption of the hydrophilic analytes. The amount of adsorbent, pH of water sample, extraction time and desorption time, type and volume of desorption solution were optimized. Following extraction for the absorbent, the phenols were quantified by HPLC. The three phenols can be determined in 0.5 to 100 nga (TM) mL(-1) concentration range, with limits of detection (at an S/N ratio of 3) ranging from 0.08 to 0.10 nga (TM) mL(-1). The repeatability was investigated by evaluating the intra- and inter-day precisions with relative standard deviations of lower than 7.5 % (n = 5). The recoveries from spiked real water samples were in the range from 84.8 to 92.0 %. The results indicate that the novel material can be successfully applied to the extraction and analysis of phenols from water samples.