A novel procedure for kinetic determination of some water-soluble vitamins of the B-group (thiamine (B1), riboflavin (B2), niacin (B3) and pyridoxine (B6)) by the concentration perturbations of the Bray-Liebhafsky (BL) oscillatory chemical system involving the catalytic decomposition of hydrogen peroxide in the presence of both hydrogen and iodate ions is proposed and validated. The method uses a Pt electrode for potentiometric monitoring of the concentration perturbations of the BL matrix in a stable non-equilibrium stationary state close to the bifurcation point. The proposed method relies on the linear relationship between maximal potential displacements, ΔEm, caused by the additional known quantities of a B species. Under the optimal established analytical conditions, linear calibration curves were obtained over the range of 0.01-1.0, 0.016-0.128, 5.0-50.0 and 0.05-2.5 μmol with the limits of detection of 0.01, 0.018, 2.6 and 0.03 μmol, as well as analytical throughput of 30, 5, 12 and 20 determinations per hour, for B1, B2, B3 and B6, respectively. The used technical approach also provides simple, effective and convenient method to assay the pharmaceutical formulations containing B1 together with other active principles such as nicotinamide and vitamin B12 as well as B3.
pulse perturbations; Bray-Liebhafsky oscillatory reaction; kinetic determination; water-soluble B vitamins; pharmaceutical preparations
