Linear Sweep Voltammetry and Impedometric Analysis of Tea Polyphenols with Potato-extracted Enzyme Modified Electrode

In this paper, we report a new measurement technique for tea polyphenols by linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The enzyme tyrosinase was also extracted from crude cheap sources such as potato. Platinum working electrode was modified with this enzyme and electrochemical techniques were performed on the enzyme-modified electrode to exploit the oxidation of polyphenols. Various grades of tea were tested for total polyphenols (TP) by linear sweep voltammetry and impedometry and the results were compared with those obtained by HPLC. A very good correlation index of 0.97 was obtained between the TP content by HPLC and LSV and that obtained between the TP content by HPLC and impedometric analysis was 0.95 for purified tyrosinase from potato. The methods exhibited very low limits of detection (0.54 mg/L) and the measurement time was also quite fast (300 seconds). The results ensured LSV and impedometric analysis to be useful techniques for determination of TP in tea and hence gradation of tea in a very simple but effective way.