Voltammetric determination of B1 and B6 vitamins using a pencil graphite electrode

Due to the importance of B-1 and B-6 vitamins for human health it is useful to develop new cheap and rapid methods for their determination. Voltammetric behavior of these vitamins on a pencil graphite electrode was investigated using cyclic voltammetry in different media. Direct quantitative determination of the two vitamins, one in the presence of the other, was done by differential pulse voltammetry. Vitamin B-1 was electroactive only in a NaOH solution generating two irreversible oxidation peaks; the first peak obtained at 250 mV is well-defined and was used in quantitative determinations. In case of vitamin B-6, a well-defined oxidation peak was observed in all investigated supporting electrolytes except for HCl. The linear concentration ranges were 10(-5)-10(-3) M for vitamin B-1 in a NaOH solution and 5 x 10(-6)-10(-3) M for vitamin B-6 in an acetate buffer solution. The obtained detection limits were 5.34 x 10(-6) M and 2.81 x 10(-6) M for vitamin B-1 and vitamin B-6, respectively. The developed method is simple and rapid and it was successfully applied in the determination of the two vitamins in pharmaceuticals. (C) 2015 Institute of Chemistry, Slovak Academy of Sciences