A STUDY OF RIBOFLAVIN DETERMINATION BY SQUARE-WAVE ADSORPTIVE STRIPPING VOLTAMMETRY ON MERCURY FILM ELECTRODES

In this work riboflavin was determined by square wave adsorptive stripping voltammetry (SWASV):riboflavin was initially adsorbed on a mercury film electrode (MFE) at a potential of 0.0 V (vs. Ag/AgCl) and at pH 12; the subsequent reductive stripping step was carried out by applying a square wave potential-time waveform on the electrode. Both a batch method (based on the rotating disk electrode configuration) and a dow approach [based on the wall-jet flow-through electrode and flow injection analysis (FIA)] were employed. Both instrumental and chemical parameters were investigated and optimized for analytical use of the technique. The limit of detection was 0.5 nmol L(-1) (for 10 min of preconcentration), the precision was 8% for the batch system (at the 10 nmol L(-1); level) and 6% for the flow system (at the 100 nmol L(-1) level); the linear range depended on the preconcentration time and the mass transfer conditions during the accumulation step. Both methods were automated and applied to the determination of riboflavin in commercial pharmaceutical products with recovery values at over 90%.