Abstract
A simple flow injection analysis-spectrophotometric system for the rapid determination of total polyphenols (TP) in tea extracts was developed. The method is based on Folin-Ciocalteu (FC) reaction, which involves the oxidation/reduction of polyphenolic compounds by FC reagent in alkaline medium, producing a blue molybdenum-tungsten complex. The linear range of the calibration graph was 10 – 500 mg gallic acid equivalent (GAE)/l. The relative standard deviation (RSD) (n=5) of the calibration graph was 2.93%. The precisions (%RSD, n=10) of the determination at low and high concentrations were 2.74% for the 10 mg GAE/l and 3.02% for the 500 mg GAE/l, respectively. The detection limit was 7 mg/l. The sample throughput was 30 per hour. The TP contents in tea extracts determined by the developed system were compared with those determined by the standard batch method and no significant difference was found (t test, at 95% confidence level).
