Sensitive electrochemical sensor for the determination of folic acid based on a bismuth-film electrode

Abstract

A bismuth-film electrode prepared ex situ on the glassy carbon electrode support exhibited favorable electroanalytical performance for voltammetric measurement of folic acid. The reduction behavior of this substance was studied in aqueous solutions within the pH 1-7, the highest response being obtained in Britton–Robinson buffer with pH 2. In the differential pulse voltammetry, the bismuth-film electrode showed a linear dynamic range from 2.5 9 10-8 to 3 9 10-5 mol dm-3 folic acid, when reaching an extraordinary repeatability of measurements [RSD(11) = 1.03 %], of determination [RSD(5) B 0.87 %], or detection capabilities (LOD = 4.1 9 10-9 mol dm-3). After optimization of key experimental and instrumental parameters, the respective method was tested by analyzing vitamin preparations and fruit juice, when the results agreed well with the declared content. Thus, the method for the determination of folic acid with a bismuth-film electrode can be proposed as an alternative to those employing mercury and amalgam electrodes, previously applied for the same purpose by our group.