Studies On Electrochemical Detection Of Bisphenol A In Food Contact Substances

BPA?Bisphenol A,BPA?,an organic compound with estrogenicity activity,is widely used in food packaging and industrial production for which can improve the mechanical properties and the availability of materials.But it not only has neural toxicity and carcinogenicity effect on the human body,but also harmful to the environment.Therefore,it is necessary to study the detection method of BPA in-depth.This paper established new,rapid and sensitive electrochemical methods for the determination of BPA.Two electrodes including a homemade electrode modified with PdNPs/GNs/IL composites?PdNPs/GNs/IL HME?and an AuNPs-IL/GNs modified glassy carbon electrode?GCE?were constructed for the electrochemical sensing of BPA.Moreover,to verify their reliability,the thus-fabricated electrochemical sensors were successfully employed to detect BPA in food contact substances.The paper mainly includes the following chapters:In chapter 1,the source,harm and detection methods now available of BPA were introduced;elaborate the composition and species of electrochemical sensor;intensively recommend the application of graphene,ionic liquid and noble metal nanoparticles in electrochemical sensors according to the research need;summed up the train thought and innovation of this paper.In chapter 2,a homemade electrode?HME?composed of palladium nanoparticles modified ionic liquid/graphene composite?PdNPs/IL/GNs?was fabricated and employed as a recyclable and convenient electrochemical sensor for detecting bisphenol A in food contact substance.PdNPs were synthesized in situ on the surface of IL/GNs HME through an effective and simple“touch”method.Owing to the surfactant-free synthesis,these PdNPs are very clean,which make the PdNPs/IL/GNs HME shows a good conductivity and high electrocatalytic activity as confirmed by the electrochemical measurements.Electrochemical oxidation of BPA on the PdNPs/IL/GNs HME was investigated by cyclic voltammetry method and the sensor exhibited higher electrochemical activity.Under optimized conditions,a good linear response was observed for the oxidation peak currents and the concentration of BPA in the range of 10?100?mol L^-11 with a detection limit?S/N=3?of 1.5?mol L^-1.To verify its reliability,the thus-fabricated electrochemical sensor was successfully employed to detect BPA in instant noodles cups.In chapter 3,IL/CS/GNs GCE was first fabricated and used as a BPA sensor.To further improve the sensitivity of the sensor,AuNPs were synthesized and modified on the surface of IL/CS/GNs GCE thus formed AuNPs-IL/CS/GNs GCE.Different methods including sodium citrate reduction,self-reduction method,and direct-immersion method were applied in the preparation of AuNPs.As direct-immersion method is a surfactant-free synthesis,the AuNPs are very clean and can be directly modified on an IL/CS/GNs GCE without any pre-treatments.Moreover,in the oxidation of BPA,the proposed AuNPs-IL/CS/GNs GCE exhibits better electrochemical activity with a higher peak current and a lower overpotential.The effect of the preparation conditions of AuNPs,pH of buffer solution and enrichment conditions of BPA were optimized;as well as investigated the stability and repeatability of the sensor.Under the optimized conditions,the BPA signals exhibited a good linear response with a distinguished detection limit?S/N=3?of 4.8 nmol L-1.The method was applied to the residual quantity of BPA detection in food packaging materials with a satisfying recovery rate ranging from 91.3%to 105.0%.In conclusion,this paper established new electrochemical methods for the determination of BPA in food contact substances,realized fast and sensitive detection of BPA through series of optimized conditions.These methods had a satisfactory recovery when applied to standard addition recovery experiments in practical samples,indicated favourable feasibility of the approaches in this paper.