| With the rapid social progress and industrial production development, more andmore negative effects are brought into human life. In recent years, chemical pollutionis serious, and a range of environment problems are also frequently exposed.Nonylphenol （NP） is accepted as environmental disrupters （EEDs）, which has beenattracted worldwide attention. Once NP is discharged into the environment, it will belongstanding. Through the biological accumulation function and food chain, itsdamages will be transferred and amplified. Thus, the development of NP detectionmethod is significant for studying its physiological functions and makingenvironmental health standards. In many of the detection means, electrochemicalmethod is extremely popular because of its advantages, such as rapid response, goodselectivity, high sensitivity, low expenditure, simple operation without complexsample preparation process, etc. In this work, simple and sensitive electrochemicalsensors are fabricated and then applied in the detection of nonylphenol in waterenvironment and food aspects. The main results are summarized as follows:Part one: Voltammetric determination of nonylphenol at a multi-walled carbonnanotubes-dihexadecyl hydrogen phosphate composite film modified glassy carbonelectrodeIn this part, the glassy carbon electrode （GCE） modified with multi-walledcarbon nanotubes （MWNTs）-dihexadecyl hydrogen phosphate （DHP） compositefilm was used to develop a NP electrochemical sensor. MWNTs pretreated by acid are inclined to get together, because of their negatively charged surface, which makesome active sites be covered. DHP contains one hydrophilic group and a pair ofhydrophobic groups （C-H chains）, and has a surface with negative charges. So DHPcan help MWNTs to be dispersed very well and exposed their surface active sides.Electrochemical response of NP is enhanced on the modified electrode than the bareone. Under optimal conditions, the oxidation peak current of NP varies linearly withits concentration over the range from2.0×10-6mol/L to2.6×10-5mol/L, with adetection limit of6.0×10-7mol/L. The sensor is successfully used to determine NP inenvironment water samples. The results are verified by high performance liquidchromatography （HPLC） method.Part two: A NP electrochemical sensor based on the carbon paste electrodemodified with cetyltrimethyl ammonium bromideIn this part, a carbon paste （CP） electrode coated with single molecule layer ofcetyltrimethyl ammonium bromide （CTAB） is utilized to improve the electrochemicalresponse of NP. CP electrode is made up of adhesives （i.e., paraffin oil） and carbonparticles. Generally, the adhesives in carbon paste electrodes are hydrophobic and canadsorb hydrophobic substrates from solutions on the electrode surfaces viahydrophobic interactions. The cationic surfactant, CTAB, has a hydrophilic head onone side and a long hydrophobic tail on the other side. Based on the hydrophobicinteraction between the hydrophobic long chain of CTAB and the paraffin oil incarbon paste, CTAB can form a stable monolayer positively charged on the electrodesurface. The electrochemical response of NP is greatly improved with the aid ofCTAB. Stirring accumulation is employed to increase the adsorption rate of NP, whichcan shorten the testing time. Under optimal conditions, the oxidation peak current ofNP varies linearly with its concentration is the range from1.0×10-7mol/L to2.5×10-5mol/L, with a detection limit of1.0×10-8mol/L. This method is successfully appliedto determine NP in some polyvinyl chloride （PVC） samples. And the results are consistent with these from high performance liquid chromatography （HPLC） method. |
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