Sensitive determination of (-)-epigallocatechin gallate in tea infusion using a novel ionic liquid carbon paste electrode.
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%.
College of Biosystems Engineering and Food Science,  Zhejiang University , Hangzhou 310058, People's Republic of China.
Kai
K
Fan
Xue
X
Luo
Jianfeng
J
Ping
Wenzhi
W
Tang
Jian
J
Wu
Yibin
Y
Ying
Qingli
Q
Zhou
D002244:Carbon / Q000737:chemistry; D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods*; D004566:Electrodes; D052578:Ionic Liquids / Q000737:chemistry; D010084:Oxidation-Reduction; D012680:Sensitivity and Specificity; D013662:Tea / Q000737:chemistry*
D052578:Ionic Liquids; D013662:Tea; D002244:Carbon; D002392:Catechin; C045651:epigallocatechin gallate