Sensitive Determination of (−)-Epigallocatechin Gallate in Tea Infusion Using a Novel Ionic Liquid Carbon Paste Electrode
2012
Fan, Kai | Luo, Xue | Ping, Jianfeng | Tang, Wenzhi | Wu, Jian | Ying, Yibin | Zhou, Qingli
This paper investigates the electrocatalytic oxidation of (−)-epigallocatechin gallate (EGCG), the main monomer flavanol found in green tea, with a novel ionic liquid, n-octylpyridinium hexafluorophosphate (OPFP) carbon paste electrode (CPE). Due to the natural viscosity and high conductivity of OPFP, this novel OPFP-CPE exhibited very attractive properties, such as high stability and electrochemical reactivity, low background current, and wide electrochemical window. Therefore, this electrode is a very good alternative to traditional chemically modified electrodes because the electrocatalytic effect can achieved without any further electrode modification. Comparative experiments were carried out using CPE and a glassy carbon electrode (GCE). With OPFP-CPE, highly reproducible and well-defined cyclic voltammograms were obtained for EGCG. Under optimal experimental conditions, the peak current of differential pulse voltammetry (DPV) response increased linearly with EGCG concentration over the range of 5.0 × 10–⁷–1.25 × 10–⁵ M. The limit of detection (LOD) and the limit of quantification (LOQ) were 1.32 × 10–⁷ and 4.35 × 10–⁷ M, respectively. The method was applied to the determination of EGCG in green tea infusion samples, and the recovery of the spiked EGCG to the diluted (10-fold) tea extract was from 87.62 to 99.51%.
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