Determination of catechol in extract of tea using carbon paste electrode modified with banana tissue

Carbon paste electrode modified with banana crude tissue CPE-B, source of Polyphenol Oxidase enzyme for determination of catechol in green tea was developed. The electrochemical properties were assessed using square wave voltammetry in phosphate buffer 0.1 M, pH 7 using standard solutions of catechol. This biosensor exhibits sensitivity 2.32 mu A/mg/L and detection limit 0.1 mg/L. Linearity range of the methods was from 1.4 to 15.7 mg/L with correlation coefficient 0.9990. Reproducibility of the signal obtained using 1.4 mg/L solution of catechol resulted with relative standard deviation 3.6% (n = 4). The biosensor was applied for the determination of catechol in green tea samples using two extraction methods: water extraction (s.d. +/- 8.3 mg/L) and phosphate buffer solution extraction (s.d. +/- 6.8 mg/L). The calculated recovery was between 89% and 92%, proving that the proposed CPE-B biosensor can be an alternative analytical tool for determination of catechol in tea. Practical applications In this study, it is reported the development of a carbon paste electrode modified with banana crude tissue (natural source of PPO enzyme), as alternative methods for determination of catechol in green tea sample using square wave voltammetry technique. In order to improve electroanalytical performance of CPEB, different parameters were optimized such as amount of modifier, pH of working solution, amplitude, frequency, and step potential. The real sample of green tea occasionally is taken in the market.