Full Paper Membrane electrodes for the simultaneous determination of vitamins B 1 , B 6 and B 12 Nesreen K.Ramadan, Marianne Nebsen*, Eman S.El Zanfaly Analytical Chemistry Department, Faculty of Pharmacy, Cairo University, Kasr-El-Aini, 11562, Cairo, (EGYPT) E-mail : Mariannenebsen@hotmail.com Received: 13 th October, 2010 ; Accepted: 23 rd October, 2010 Thiamine hydrochloride (B 1 ); Pyridoxine hydrochloride (B 6 ); Cyanocobalamin (B 12 ); -Cyclodextrin; Ammonium reineckate; Pharmaceutical formulations. KEYWORDS ABSTRACT Three poly(vinyl chloride) matrix membrane electrodes responsive to some vitamins, thiamine hydrochloride (B 1 ), pyridoxine hydrochloride (B 6 ) and cyanocobalamin (B 12 ) were developed, described and characterized. Pre- cipitation based technique with ammonium reineckate (R) anion as electroactive material in poly(vinyl chloride) (PVC) matrix with B 1 and B 6 cations was used for electrodes 1 and 2 fabrication respectively. - Cyclodextrin (-CD)-based technique with ammonium reineckate as fixed anionic site for B 12 in PVC matrix was used for fabrication of electrode 3. Fast and stable Nernstian responses near 1x10 -6 -1x10 -2 M for vitamin B 1 , 1x10 -5 -1x10 -2 M for vitamin B 6 and 1x10 -7 -1x10 -4 M for vitamin B 12 over pH range 1-3 for the three electrodes revealed the performance characteristics of these electrodes which were evaluated according to IUPAC recommen- dations. The three proposed electrodes were successfully applied for the determination of vitamins in some pharmaceutical formulations and in hu- man spiked plasma samples. Validation of the method according to the quality assurance standards showed the suitability of the proposed elec- trodes for the use in the quality control assessment of these drugs.  2010 Trade Science Inc. - INDIA INTRODUCTION Vitamins are commonly used in the treatment and prevention of vitamins deficiency. Thiamine deficiency leads to the development of a syndrome known as beri- beri [1] . Pyridoxine deficiency leads to sideroblastic anaemia, dermatitis, cheilosis, and neurological symp- toms such as peripheral neuritis, and convulsion. Pyri- doxine has also been used to treat seizures due to he- reditary syndromes of pyridoxine deficiency or depen- dency in infants [1] . Vitamin B 12 deficiency leads to the development of megaloblastic anaemias and demyelination and other neurological damage. Determination of vitamins is described in the British Pharmacopoeia [2] by titrimetric method for B 1 and B 6 and spectrophotometric method for B 12 . The three vi- tamins were simultaneously determined by several meth- ods including HPLC [3-7] , TLC [8,9] , micellar electrokinetic Trade Science Inc. Volume 2 Issue 2 RREC, 2(2), 2010 [78-87] Electrochemistry Electrochemistry Research & Reviews In ISSN : 0974 - 7540