title: A portable electrochemical sensor for caffeine and (-)epigallocatechin gallate based on molecularly imprinted poly(ethylene-co-vinyl alcohol) recognition element.
abstract: The U.S. Food and Drug Administration allows a maximum of 72 mg of caffeine per 12 oz. serving (6 mg/oz). Consuming 400 mg of caffeine 3 times daily for 7 days may develop sleep disruption effects. However, it is still very hard for people to estimate how much caffeine is intake daily. Moreover, (-)epigallocatechin gallate (EGCG) is studied a potent antioxidant that may have therapeutic properties for anti-aging and cancer. Conventionally, both caffeine and EGCG could be measured by the protocols of high performance liquid chromatography; however, high precision instruments are required. In this work, the caffeine and EGCG are used as the template molecules and imprinted into poly(ethylene-co-vinyl alcohol), EVAL, via solvent evaporation. The EVAL membrane is then used as the sensing element for electrochemical analysis after templates removal. From the cyclic voltammetry measurement of the caffeine, the peak oxidation potential is shifted from 0.36 to 0.46 V when the final concentration of caffeine is from 0.01 to 1 mg/mL, and the highest current density is about 0.18 microA/cm2. The caffeine and EGCG concentrations measured in three real samples are about 0.10-0.13 mg/mL and 0.49-1.74 mg/mL, respectively. This molecularly imprinted polymeric coated electrode is potential employed as a home-care system.
authors.affiliation: Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 811, Taiwan.
authors.forename: I-Chegn
authors.initials: IC
authors.lastname: Chung
authors.forename: Chih-Chun
authors.initials: CC
authors.lastname: Chang
authors.forename: Han-Sheng
authors.initials: HS
authors.lastname: Chiu
authors.forename: Shih-Fan
authors.initials: SF
authors.lastname: Jiang
authors.forename: Mei-Hwa
authors.initials: MH
authors.lastname: Lee
authors.forename: Cho-Liang
authors.initials: CL
authors.lastname: Chung
authors.forename: Bin-Da
authors.initials: BD
authors.lastname: Liu
authors.forename: Chun-Yueh
authors.initials: CY
authors.lastname: Huang
authors.forename: Hung-Yin
authors.initials: HY
authors.lastname: Lin
mesh_terms: D002110:Caffeine / Q000032:analysis*; D002392:Catechin / Q000031:analogs & derivatives* / Q000032:analysis; D004563:Electrochemistry / Q000295:instrumentation*; D011145:Polyvinyls / Q000737:chemistry*
chemical_list: D011145:Polyvinyls; C020320:ethylene-vinyl alcohol copolymer; D002110:Caffeine; D002392:Catechin; C045651:epigallocatechin gallate