Advanced electrochemical platform for simple and rapid quantification of tannic acid in beverages using batch injection analysis with amperometric detection

In this work, an advanced electrochemical platform was developed for the simple, rapid and sensitive determination of the polyphenolic compound tannic acid in various beverages using the combination of batch injection analysis with amperometric detection on a screen-printed carbon electrode. Several experimental parameters (pH of supporting electrolyte, detection potential, dispensing rate, injected volume, stirring) were consistently evaluated. The most favorable analytical performance in terms of sensitivity, selectivity, repeatability and sampling frequency was obtained in Britton-Robinson buffer pH 5.0 at a detection potential of +0.6 V vs. Ag/AgCl, a dispensing rate of 204 & mu;L/s and an injected volume of 80 & mu;L under stirring condition (1500 r.p.m.). The presented platform has advantages for routine analysis including portable and small-scale experimental setup, low sample consumption (& SIM;100 & mu;L), simple sample preparation (dilution in supporting electrolyte), high sampling frequency (180 injections per hour), low limit of detection (80 nM) and suitable precision (RSD = 4.2% for 10 & mu;M tannic acid, n = 20). The applicability of the method was verified by analyzing several beverage samples (tea, wine) in spike-recovery assay with the recovery values for tannic acid ranging from 94 to 101 %.