Membrane electrodes for the simultaneous determination of vitamins B1, B6 and B12Author(s): Nesreen K.Ramadan, Marianne Nebsen*, Eman S.El Zanfaly
Three poly(vinyl chloride)matrixmembrane electrodes responsive to some vitamins, thiamine hydrochloride (B1), pyridoxine hydrochloride (B6) and cyanocobalamin (B12) were developed, described and characterized. Precipitation based technique with ammonium reineckate (R) anion as electroactive material in poly(vinyl chloride) (PVC) matrix with B1 and B6 cations was used for electrodes 1 and 2 fabrication respectively. ï¢- Cyclodextrin (ï¢-CD)-based technique with ammoniumreineckate as fixed anionic site for B12 in PVC matrix was used for fabrication of electrode 3. Fast and stable Nernstian responses near 1x10-6-1x10-2M for vitamin B1, 1x10-5-1x10-2Mfor vitamin B6 and 1x10-7-1x10-4Mfor vitamin B12 over pH range 1-3 for the three electrodes revealed the performance characteristics of these electrodes which were evaluated according to IUPAC recommendations. The three proposed electrodes were successfully applied for the determination of vitamins in some pharmaceutical formulations and in human spiked plasma samples. Validation of the method according to the quality assurance standards showed the suitability of the proposed electrodes for the use in the quality control assessment of these drugs.