Electrochemical determination of catechol in tea samples using anthraquinone modified carbon paste electrode

Abstract

Electrochemical investigation of catechol using square wave voltammetry with anthraquinone modified carbon paste electrode was found to be very sensitive. Compared with the unmodified carbon paste electrode, the anthraquinone modified electrode remarkably increases the peak currents of catechol, and greatly lowers the peak potential separation. Two varieties of tea, namely green, and black variety: Wush Wush tea, from Ethiopia, known by its brand name were investigated. Responses for the extracts using ethanol: water (1:4) % v/v showed green tea to be superior in catechol content. Optimization of different variables such as pH of working solution, modifier composition and square wave parameters such as frequency, amplitude and step potential were made to improve the method efficiency during the experiment. The reproducibility for the nine repeated analysis of 80 μmol·L－1 of catechol gave a relative standard deviation of 3.65% and linear calibration plots were obtained in the range 6 to 80 μmol·L－1 with (R = 0.998) and the detection limit with (S/N = 3) was as low as 2.155 x 10－7 mol·L－1.