Rutin determination in pharmaceutical formulations using a carbon paste electrode modified with poly(vinylpyrrolidone)

A carbon paste electrode modified with poly(vinylpyrrolidone) (PVP) was developed for the determination of rutin. PVP enhances the adsorption of rutin on the electrode surface due to the presence of hydrogen bonding between the imide group in PVP and the hydroxyl group in rutin. The current responses in cyclic and linear sweep voltammetric experiments were investigated and an oxidation peak was observed at +0.87 V vs. Ag/AgCl. Several parameters were investigated to evaluate the performance of the modified electrode. The best analytical response was obtained employing (75:15:10%, w/w/w) graphite powder:Nujol:PVP, with an accumulation time of 10 min, scan rate of 100 mV s−1 and 0.1 M phosphate buffer solution (pH 6.0) as supporting electrolyte. The analytical curve was linear for rutin concentrations of 3.9 × 10−7 to 1.3 × 10−5 M (r = 0.9991) and the detection limit was 1.5 × 10−7 M. The recovery of rutin from pharmaceutical samples ranged from 98.3 to 101.7% and the relative standard deviation was 3.3% for a solution containing 7.7 × 10−6 M rutin (n = 5). This electrode was successfully applied to the determination of rutin in pharmaceutical formulations. The results obtained using the proposed modified carbon paste electrode and those obtained by the standard method are in agreement at the 95% confidence level.