Cathodic adsorptive stripping voltammetric determination of rutin in soybean cultivars

A highly sensitive and selective cathodic adsorptive stripping voltammetric method for determination of rutin is presented. The method relies on the accumulation of a Cu(II)-rutin complex at a hanging mercury drop electrode (HMDE), followed by its reduction during a differential pulse voltammetric scan. The electrochemical behavior of the Cu(II)-rutin complex at HMDE was investigated by cyclic voltammetry. Results show that the electrode process is adsorption-controlled and gradually becomes less reversible at high scan rates where peak separation grows. Under the optimized conditions (phosphate buffer pH 6, −1.000 V accumulation potential, 180 s accumulation time, 70 mV pulse amplitude, 50 mV s−1 scan rate and 1.6 × 10−6 M Cu(II) concentration), the reduction peak current (Ipc) of the Cu(II)-rutin complex is linear (Ipc (nA) = 10.070 + 1.9 × 108 [Rutina]) to rutin concentration in the range from 2.0 × 10−7 to 1.4 × 10−6 M, with a correlation coefficient of 0.999. The detection and quantification limits obtained were 7.0 × 10−9 M and 2.2 × 10−8 M, respectively. The method was successfully applied to the determination of rutin in soybean cultivars, with recoveries of 94-105%.