title: Determination of tannin in green tea infusion by flow-injection analysis based on quenching the fluorescence of 3-aminophthalate.
abstract: A flow-injection analytical system was developed to determine tannin content in green tea infusions. The flow-injection system is based on measuring the quenching effect of tannin on the fluorescence of 3-aminophthalate. Fluorophore was obtained by auto-oxidation of luminol during solution preparation. System performance was satisfactory for routine analysis (sample throughput >20 h(-1); linear dynamic range for tannic acid, 0.005-0.3 mg/mL; linear dynamic range for green tea tannin, 0.02-1.0 mg/mL; CV < 3%). The flow-injection method is immune from interference by coexisting ascorbate in green tea infusion. Analytical results were verified by the ferrous tartrate method, the Japanese official analytical method.
authors.affiliation: Department of Bio-Industrial Mechatronics Engineering, College of Bio-resources and Agriculture, and Department of Biomedical Engineering, National Taiwan University Hospital-College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Richie L C
authors.initials: RL
authors.lastname: Chen
authors.forename: Chun-Hsun
authors.initials: CH
authors.lastname: Lin
authors.forename: Chien-Yu
authors.initials: CY
authors.lastname: Chung
authors.forename: Tzong-Jih
authors.initials: TJ
authors.lastname: Cheng
mesh_terms: D001205:Ascorbic Acid; D017022:Flow Injection Analysis / Q000379:methods*; D005453:Fluorescence; D006863:Hydrogen-Ion Concentration; D010795:Phthalic Acids / Q000737:chemistry*; D011786:Quality Control; D012680:Sensitivity and Specificity; D013634:Tannins / Q000032:analysis*; D013662:Tea / Q000737:chemistry*
chemical_list: C506355:3-aminophthalate; D010795:Phthalic Acids; D013634:Tannins; D013662:Tea; D001205:Ascorbic Acid