title: Simultaneous determination of 15 phenolic compounds and caffeine in teas and mate using RP-HPLC/UV detection: method development and optimization of extraction process.
abstract: A reversed-phase high performance liquid chromatographic coupled to ultraviolet detection (RP-HPLC/UV) method was developed for simultaneous determination of 15 phenolic compounds and caffeine in TEAS (green tea, oolong tea, black tea and mate). Furthermore, the extraction process of total phenolic contents (TPC) from TEAS were optimized using response surface methodology (RSM) based on a central composite design (CCD) and then applied to extraction of TEAS. The best conditions obtained using the model were as follow: green tea--extraction time of 123 min, extraction temperature of 70 °C and ethanol concentration of 75%, oolong tea--extraction time of 98 min, extraction temperature of 70 °C and ethanol concentration of 69%, black tea--extraction time of 105 min, extraction temperature of 71 °C and ethanol concentration of 63%, and mate--extraction time of 103 min, extraction temperature of 71 °C and ethanol concentration of 61%. Among the extraction methods used in this study, heat-reflux extraction was found to result in the highest values of TPC. The chromatographic peaks of the 16 studied compounds were successfully identified by comparing their retention time and UV spectra with the reference standards. Method validation was performed by means of linearity, sensitivity, selectivity, accuracy and precision. The developed method was found to be simple, specific and reliable and is suited for routine analysis of phenolic compounds and caffeine in TEAS.
authors.affiliation: School of Applied Sciences, Kyungpook National University, Daegu 702-701, Republic of Korea.
authors.forename: In Kyung
authors.initials: IK
authors.lastname: Bae
authors.affiliation: National Agricultural Products Quality Management Service, Seoul 150-804, Republic of Korea.
authors.forename: Hyeon Mi
authors.initials: HM
authors.lastname: Ham
authors.affiliation: National Agricultural Products Quality Management Service, Seoul 150-804, Republic of Korea.
authors.forename: Min Hee
authors.initials: MH
authors.lastname: Jeong
authors.affiliation: National Agricultural Products Quality Management Service, Seoul 150-804, Republic of Korea.
authors.forename: Dong Ho
authors.initials: DH
authors.lastname: Kim
authors.affiliation: National Agricultural Products Quality Management Service, Seoul 150-804, Republic of Korea. Electronic address: rex7878@korea.kr.
authors.forename: Ho Jin
authors.initials: HJ
authors.lastname: Kim
mesh_terms: D002110:Caffeine / Q000032:analysis*; D028241:Camellia sinensis / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D056148:Chromatography, Reverse-Phase; D000431:Ethanol / Q000737:chemistry; D057230:Limit of Detection; D010636:Phenols / Q000032:analysis*; D010936:Plant Extracts / Q000032:analysis*; D015203:Reproducibility of Results; D013662:Tea / Q000737:chemistry
chemical_list: D010636:Phenols; D010936:Plant Extracts; D013662:Tea; D002110:Caffeine; D000431:Ethanol
keywords: Caffeine; Phenolic compounds; RP-HPLC/UV; Response surface methodology; Tea; Validation