Adsorptive Stripping Voltammetric Detection of Tea Polyphenols at Multiwalled Carbon Nanotubes‐Chitosan Composite Electrode

Abstract

This study reports the catalytic oxidation and detection of tea polyphenols (TPs) at glassy-carbon electrode modified with multiwalled carbon nanotubes-chitosan (MWCNTs-CS) film. The adsorption of TPs at the surface of the MWCNTs through p -p conjugation prevents the aggregation of nanotubes and induces a stable MWCNTs suspension in water over 30 days. Based on the adsorptive accumulation of polyphenols at MWCNTs, TPs is sensitively and selectively detected by adsorptive stripping voltammetry. The accumulation conditions and pH effect on the adsorptive stripping detection were examined. The linear range was found to be 100 to 1000 mg L À1 with a detection limit of 10 mg L À1 (S/N ¼ 3) for 2.5 min accumulation. Additionally, the MWCNTs-CS electrode is easily renewed by applying positive potential to remove the adsorbed TPs. This method was successfully applied to determine TPs in commercially available teas with satisfied result compared with that of conventional spectrometric analysis.

Novel Coulometric Approach to Evaluation of Total Free Polyphenols in Tea and Coffee Beverages in Presence of Milk Proteins

“…Different types of voltammetry on stationary electrodes (Ziyatdinova and Budnikov 2005) including chemically modified (Xiao et al 2006;Guo et al 2009) have been developed for polyphenols detection. Amperometric laccase-based biosensors for the determination of polyphenols in wines (Gomes and Rebelo 2003;Fernandes and Rebelo 2009) and plant extracts are described (Diaconu et al 2010).…”

A Selective Simultaneous Determination of Levodopa and Serotonin Using a Glassy Carbon Electrode Modified with Multiwalled Carbon Nanotube/Chitosan Composite

“…The subtle electronic behavior of CNTs reveals that they have the ability to promote electron-transfer reaction when used as electrode materials for the development of electrochemical sensors. Indeed, sensors based on CNTs have improved the voltammetric response (lower overvoltages and higher peak currents) of a variety of clinical, biological and environmental compounds [1][2][3][4][5][6].…”

Characterisation of catechins in green and black teas using square-wave voltammetry and RP-HPLC-ECD

“…The polyphenolic content of green tea extract has also been determined by differential pulse voltammetry at graphite electrode, and the results were consistent with quantification using HPLC (Romani, Minunni, Mulinacci, Pinelli, & Vincieri, 2000). Recently, the use of various voltammetric techniques has been combined with modified catechin sensors (Goodwin, Banks, & Compton, 2006;Guo, Zheng, Mo, & Ye, 2009).…”