Determination of tannin in green tea infusion by flow-injection analysis based on quenching the fluorescence of 3-aminophthalate.
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.
Chen
Richie L C
RL
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.
Lin
Chun-Hsun
CH
Chung
Chien-Yu
CY
Cheng
Tzong-Jih
TJ
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*
C506355:3-aminophthalate; D010795:Phthalic Acids; D013634:Tannins; D013662:Tea; D001205:Ascorbic Acid