title: Rapid and selective quantification of L-theanine in ready-to-drink teas from Chinese market using SPE and UPLC-UV.
abstract: An ultra performance liquid chromatography (UPLC) method combined with solid phase extraction (SPE) sample pre-treatment was developed and validated for the rapid quantification of L-theanine in ready-to-drink (RTD) teas. UPLC analysis of twenty-seven RTD teas from the Chinese market revealed that the L-theanine levels in various types of RTD teas were significantly different. RTD green teas were found to contain highest mean L-theanine level (37.85±20.54 mg/L), followed by jasmine teas (36.60±12.08 mg/L), Tieguanying teas (18.54±3.46 mg/L) black teas (16.89±6.56), Pu-erh teas (11.31±0.90 mg/L) and oolong teas (3.85±2.27 mg/L). The ratio of total polyphenols content to L-theanine content could be used as a featured parameter for differentiating RTD teas. L-theanine in RTD teas could be a reliable quality parameter that is complementary to total polyphenols.
authors.affiliation: Advanced Measurement & Data Modeling, Unilever R&D Shanghai, 66 Lin Xin Road, Linkong Economic Development Zone, Shanghai 200335, People's Republic of China. leon.chen@unilever.com
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Chen
authors.forename: Yun
authors.initials: Y
authors.lastname: Wang
authors.forename: Weiqi
authors.initials: W
authors.lastname: Song
authors.forename: Bo
authors.initials: B
authors.lastname: Zhao
authors.forename: Yuling
authors.initials: Y
authors.lastname: Dou
mesh_terms: D028241:Camellia sinensis / Q000737:chemistry*; D002681:China; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D005971:Glutamates / Q000032:analysis* / Q000302:isolation & purification; D059808:Polyphenols / Q000032:analysis* / Q000302:isolation & purification; D052616:Solid Phase Extraction / Q000379:methods*; D013662:Tea / Q000737:chemistry*
chemical_list: D005971:Glutamates; D059808:Polyphenols; D013662:Tea; C026166:theanine