Research Of Electrochemical Biosensor Technology For Rapid Detection Of Phenolic Pollutants

Phenolic contaminants are very important monitoring targets in environment.Phenol is a high toxic substances,which is discharged into natural water bodiesprimarily by industrial waste water. The priority pollutants blacklist in the wateridentified by our country is a total of fourteen categories, the fifth category is phenolicpollutants, and thus the monitoring of phenolic compounds is very important.Biosensor has the advantages of simple, rapid, accurate, sensitive,selective and so on.And it is easy to implement automation and online monitoring. Thus, the developmentof phenolic compounds biosensors becomes the research focus in the technology ofrapid determination of phenolic pollutants.This article was based on the electrocatalytic oxidation of phenol on preciousmetals and carbon nanotubes to develop electrochemical sensors and electrochemicalbiosensors used for determining phenol compounds. The voltammetric behaviours andelectrocatalytic michenism of phenol compounds at the electrodes were studied. Themain contents of the research are as follows:1. Gold particles were electrochemically deposited on a Nafion film coatedglassy carbon electrode to prepare a sensor for determing hydroquinone. Theelectrochemica1 behaviors of hydroquinone at the sensor based on gold particles andNafion film modified glassy carbon electrodes (Au/Nafion/GCE) were studied bycyclic voltammetry. The experimental parameters were optimized, and under theoptimal conditions, the oxidation peak current of hydroquinone was proportional tothe concentration of hydroquinone over the range of 5.0×10-5~1×10-3 mol/L with thedetection limit of 7.0×10-7 mol/L ( r = 0. 9970) .2. Gold particles and multiwall carbon nanotubes(MWNTs) film modified glassycarbon electrodes(Au/MWNTs/GCE) were prepared by drop-coating method andelectrochemica1 deposition method. A voltammetric method for determininghydroquinone was developed. The electrochemica1 behaviors of hydroquinone at thesensor were studied by cyclic voltammetry. The experimental parameters wereoptimized, and under the optimal conditions, the oxidation peak current ofhydroquinone was proportional to the concentration of hydroquinone over the rangeof 5.0×10-6~3.0×10-3 mol/L with the detection limit of 1.0×10-6 mol/L ( r = 0. 9988) .3. An amperometric biosensor for the detection of phenolic contaminants wasdescribed. Tyrosinase and bovine serum albumin were immobilized by glutaraldehydecross-linking method on the surface of the electrode which modified with multiwall carbon nanotubes. The prepared conditions of the biosensor were optimized. Thelinear range of phenol, hydroquinone, catechol, bisphenol A which were determinedby the biosensor are 4.0×10-7~1.0×10-5 mol/L, 2.0×10-7~6.0×10-5 mol/L,2.0×10-7~1.0×10-5 mol/L, 2.0×10-6~1.0×10-4 mol/L, with the linear correlationcoefficient of 0.9995, 0.9989, 0.9990, 0.9982 respectively. And the detection limitsare 2.0×10-7 mol/L, 2.0×10-7 mol/L, 2.0×10-7 mol/L, 5.0×10-7 mol/L respectively.The methods exhibited good recovery and reproducibility when the sensor wasused to analyze the real samples. The electrochemical sensors and biosensors possessmany advantages, such as: high sensitivity, good reproducibility, fast response, and soon. This methods possess good prospect in the applications of determining phenolcompounds in real samples.