A simple amperometric method for determination of total phenol by a polyphenol oxidase paper based biosensor

Phenolic compounds are known as environmental pollutants. Among of all the pollutants, phenols have the notoriety because of their strong stability, great harmfulness and poor biodegradability [1]. Therefore efficient and simple methods were introduced for determination of phenols in environmental monitoring [2]. In this research, a facile method was developed for the total phenol determination by immobilization of the potato tissue polyphenol oxidase at fiber matrices of the paper disc. The potato tissue in phosphate buffer solution as the source of the enzyme was immobilized at fiber matrices of the paper disc via physical adsorption. After drying, the mediator potassium hexacyanoferrate was added to the enzymatic paper disc. This paper disc after drying was placed on the top of the graphite screen printed electrode and was connected to potentiostat/ galvanostat electrochemical device. Electrochemical characterization of this biosensor was studied by cyclic voltammetry and electrochemical impedance spectroscopy methods. After optimization of effective parameters such as pH, potato tissue percentage and amount of mediator loading, phenol measurements were done by amperometric method. This biosensor showed a linear response for phenol in the wide concentration range of 0.2-800 µM with a detection limit about 0.13 µM and limit of quantification about 0.4 µM. The selectivity against some interference were evaluated. Furthermore, electrochemical detection was used for the determination of phenols in real samples like olive oil, river and waste water of wood factory.