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

Riboflavin (or vitamin B-2) 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 B-2 undergoes an adsorption-controlled quasireversible 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 mu mol L-1 vitamin B-2 and the second from 1.0 to 9.0 mu mol 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. (C) 2014 Elsevier B.V. All rights reserved.