Manganese dioxide-modified carbon paste electrode for voltammetric determination of riboflavin

A carbon paste electrode bulk was modified with MnO2 and investigated for use as an electrochemical sensor for riboflavin (vitamin B-2) using differential pulse voltammetry (DPV). Riboflavin displays a well expressed oxidation peak at -0.15 V (versus Ag/AgCl) in solutions with a pH value of 2. Effects of pH value, pulse amplitude and pulse time were optimized by employing DPV. The signals obtained are linearly related to the concentrations of riboflavin in the range from 0.02 to 9 mu M. Other features include a 15 nM detection limit, and good reproducibility (+/- 3 %) and repeatability (+/- 2 %). Interferences by common compounds were tested, and the method was successfully applied to the determination of riboflavin in pharmaceutical formulations where is gave recoveries in the range from 95 to 97 %.