| Bisphenol A (BPA), is an important industrial chemical, that has heavy demands in our daily life, where is used in materials such as baby water bottles, food cans, food packaging industries, etc. With more than one billion pounds produced each year, BPA is one of the most abundantly produced chemicals in the world. As an endocrine disrupting compound, BPA may cause numerous health concerns including sexual precocity, diabetes, cancer etc. BPA application is now restricted because it is easily leachable from household items and the public is at high risk of exposure to its toxicity. Therefore, there is an increasingly demand for routine quantification of BPA.Electrochemical analysis is a good detection method that is simple to use, sensitivity, low cost, environmentally friendly and more which is used to monitor environment and food safety, drug analysis, et al. Besides, comparing with nature molecular, molecularly imprinted polymer as bionic material with identified property, has more good characteristics, such as stability at heated, acid or alkali condition, which is also attracted much attention in the field of detection or separation.This work focuses on environmental protection through electrochemical detection couple with function nanomaterials and molecularly imprinted technology. With good absorption property of phenol, graphene was selected as the main material for the modified electrode. Innovating production of nanocomposites, graphene coupled with gold particle as well as reduced graphene oxide coupling with gold nanoparticle were made. These nanocomposites were combined with advanced technology, electrochemical methods and molecularly imprinted polymers, to establish new ways for highly selective and sensitive methods for detecting BPA. This paper is comprised of the following two parts,1. To develop a new method to synthesize graphene-AuNPs composites, and to characterize its morphology and structure through the use of X-ray diffraction, scanning electron microscopy, and EDS energy spectrum. In addition, the behavior of [Fe(CN)6]3-/4- and bisphenol A at the graphene-AuNPs/GCE electrode were supervised by cyclic voltammetry, Electrochemical impedance spectroscopy, linear voltammetry and differential pulse voltammetry. The cyclic voltammograms results show that graphene-AuNPs could enhance the current response of bisphenol A at the modified electrode as well as decrease the passivation effect on the electrode. Under optimized conditions, bisphenol A at graphene-AuNPs/GCE electrode had a good linear range from 5.7 to 570 ng/mL, with the linear regression equation:Ipa=0.00325c+7.28× 10-4, (R2=0.992), and from 570 to 2280 ng/mL, with linear regression equation: Ipa=9.136×10-4c+1.256, (R2=0.983) with the limit of detection (LOD) of 1.9 ng/mL (S/N=3). Graphene-AuNPs/GCE electrochemical sensor was used to analyze bisphenol A in water with a recovery rate from 78.91 to 115.54%. Compared with the results of HPLC, the correlation is strong. Thusly, the method of graphene-AuNPs/GCE sensor is reliable and suitable for water detection.2. On the basis of the previous chapter on this work, rGO-AuNPs composite was prepared using a similar method as what we had done. The nanoparticles were characterized by X-ray diffraction, Raman spectroscopy, infrared spectroscopy, scanning electron microscopy and EDS energy spectrum. Molecularly imprinted polymer of BPA was formed on the surface of the rGO-AuNPs/GCE electrode, which had increased recognition sites after it was modified with rGO-AuNPs nanoparticles. Under optimized conditions, the linear range of MEPs/rGO-AuNPs/GCE was from 0.25 to 17.50 uM with equation:Ip (μA)= 0.259c (μM)+0.025 (R2=0.998), and from 17.50 to 100.00 uM with equation:Ip (μA)= 0.073c (μM)+3.306 (R2=0.999). The LOD was as follows: 0.083μM (S/N=3). In addition, the analysis of BPA in soil sample had a good recovery between 93.36 to 118.8%, This proves that the sensor was suitable to be applied in environmental monitoring. Compared with HPLC, correlation of method was 99.8%, which proves that the method can be used for the detection of real samples.The innovation of this paper is trying to modify gold nanoparticles on the graphene surface direct through the cation-π effect, and the composite material were successfully obtained. In addition, new molecularly imprinted polymer which o-phenylendiamine were as monomers for the selection of bisphenol A was prepared. Combinating with the nanometer materials and molecularly imprinted polymer, the electrochemical sensor for detecting BPA were established. And the two kinds of established methods can successfully applied to detection of bisphenol A in the environment, indicating that they have reference value for practical application. |
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