New voltammetric procedure for determination of thiamine in commercially available juices and pharmaceutical formulation using a lead film electrode

A simple, reliable and reproducible method, based on adsorptive stripping voltammetry (AdSV), for determination of vitamin B1 (thiamine) in pharmaceutical preparation and food is described in this paper. The in situ plated lead film electrode was used as a working electrode. The lead film was formed and thiamine was accumulated at −1.25 V (vs. Ag/AgCl) on a glassy carbon electrode. Then, the preconcentrated thiamine was reduced by scanning the potential of the electrode from −1.25 to −1.55 V using a square-wave technique. The linear range was from 0.0133 to 0.265 mg L−1 for vitamin B1, with the regression coefficient of 0.999. The detection limit for vitamin B1 was 0.0053 mg L−1 for the accumulation time 120 s. The method developed was applied to the determination of thiamine in certified reference material (BCR-485), pharmaceutical formulation and commercially available juices, and the assay results were satisfactory.