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 strip ping voltammetry (SWASV):riboflavin was initially adsorbed on a mercur y 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 applyi ng a square wave potential-time waveform on the electrode. Both a batc h method (based on the rotating disk electrode configuration) and a do w approach [based on the wall-jet flow-through electrode and flow inje ction analysis (FIA)] were employed. Both instrumental and chemical pa rameters were investigated and optimized for analytical use of the tec hnique. The limit of detection was 0.5 nmol L(-1) (for 10 min of preco ncentration), the precision was 8% for the batch system (at the 10 nmo l L(-1); level) and 6% for the flow system (at the 100 nmol L(-1) leve l); the linear range depended on the preconcentration time and the mas s 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%.