Determination of gallic acid by an oscillating chemical reaction using the analyte pulse perturbation technique

A new analytical method for the determination of gallic acid by the sequential perturbation caused by different amounts of acid on the oscillating chemical system involving the Cu(II)-catalysed reaction between hydrogen peroxide and sodium thiocyanate in an alkaline medium is proposed. The method relies on the linear relationship between the changes in the oscillation amplitude of the chemical system and the concentration of gallic acid, which is in this work exposed for the first time. The calibration curve is linear over the range 0.075-2.00 mu mol of gallic acid. The method features good precision (rsd 0.67%) and excellent throughput (14 samples h(-1)) thanks to the expeditiousness with which the steady state is regained after each perturbation. Some aspects of the interaction of gallic acid with the oscillating chemical system are discussed. This is the first reported determination of gallic acid based on an oscillating reaction.