Hydroxy-Iron/β-cyclodextrin-Film Amperometric Sensor for the Endocrine Disruptor Substance Bisphenol-A in an Aqueous Medium with Reduced Fouling Effects

Abstract

Amperometric sensors for the detection of bisphenol A (BPA) were developed by drop coating an amorphous hydroxy iron product (FeOx) and its composites with β-cyclodextrin (BCD) on the surface of glassy carbon electrodes (GCE). The composite materials were prepared in an aqueous medium by adding a stoichiometric mixture of iron (II) and iron (III) ions into a strongly alkaline solution of BCD under reflux at 90°C. The electrochemical oxidation behavior and detection of BPA at the modified electrode was investigated by using cyclic voltammetry. The potentials (vs. Ag/AgCl) for BPA-oxidation at the modified electrodes (727–771 mV) were significantly lower than observed for the bare GCE (834 mV) in aq. KCl. The lowest oxidation potential was observed for the iron oxide film without BCD. However, the analytical figures of merit as an amperometric sensor based on cyclic voltammetric peak measurements were the best in the case of the iron oxide which was synthesized in the presence of BCD. Its two orders of magnitude of linearity, sub-micromolar detection limit, and reproducibility within experimental error make this sensor potentially exploitable for real sample analysis. The significantly shorter linearity range of the bare GCE indicated that the iron oxide product and its composites with BCD were less prone to passivation by BPA oxidation products. Application of the sensor in a real sample matrix was also demonstrated successfully using “Stoney Ginger Beer samples” spiked with a saturated aq. solution of BPA. The recovery rate was 100%.