Multi-Analyte Sensor Based on Pencil Graphite Electrode for Riboflavin and Pyridoxine Determination

Riboflavin (VB2) and pyridoxine (VB6) are two of the eight water-soluble B vitamins that play an essential role and are correlated in normal function of the body. In the present study, cyclic voltammetry demonstrated that in Britton-Robinson buffer (pH 5.00) VB2 undergoes a quasi-reversible electron transfer reaction and the oxidation of VB6 is irreversible, both electrochemical systems being diffusion controlled at the pencil graphite electrode (PGE) surface. Also, a sensitive and selective voltammetric procedure has been developed for the simultaneous determination of the two compounds using PGE and square wave voltammetry (SWV). Two well-defined oxidation peaks with a voltammetric separation of more than 1.10 V were obtained in Britton-Robinson buffer (pH 5.00). The SWV curves exhibited linear responses with riboflavin and pyridoxine concentrations. Thus, for VB2 two linear concentration ranges of 1.00 center dot 10(-7)-5.00 center dot 10(-5 )M and 5.00 center dot 10(-5)-7.50 center dot 10(-4 )M were obtained and in the case of VB6 the linear response was between 2.50 center dot 10(-5 )M and 2.50 center dot 10(-3 )M. The detection limits for VB2 and VB6 were 7.38 center dot 10(-8 )M and 1.10 center dot 10(-5 )M, respectively. The applicability of PGE was successfully proved for simultaneous determination of VB2 and VB6 in pharmaceutical tablets with good accuracy and precision.