Electrochemical sensor based on bismuth-film electrode for voltammetric studies on vitamin B2 (riboflavin)

Riboflavin (or vitamin B2) was successfully studied by voltammetric techniques and determined in oral, syrup and tablet samples using an ex situ plated bismuth-film electrode (BiFE). Cyclic voltammetry demonstrated that in acetate buffer (pH 4.0) vitamin B2 undergoes an adsorption-controlled quasi-reversible electron transfer reaction. The peak potentials observed were pH-dependent, involving the same numbers of protons and electrons. The calibration curve provided by square-wave adsorptive stripping voltammetry (SWAdSV) exhibited two slopes: the first ranged from 0.3 to 0.8 μmol L−1 vitamin B2 and the second from 1.0 to 9.0 μmol L−1. In the case of the first slope, the detection limit was 100 nmol L−1 and the quantification limit was 300 nmol L−1. Also, for the measurements, excellent selectivity, repeatability and stability were attained. Fluorescence was employed as the comparative technique and the outstanding performance of the BiFE-SWAdSV for riboflavin determination was verified.