Background: Folic acid (pteroylglutamic acid, FA), known as a water-soluble vitamin
of B complex family, plays an important role in the human body. However, excess intake of FA
would mask the vitamin B12 deficiency symptoms, which may lead to other health risks. Therefore,
it is very important to develop a method for the sensitive and selective determination of FA in natural
sources, fortified foods and multivitamin preparations.
Methods: An electrochemical sensor was fabricated for the analysis of FA, which was based on
electropolymerized molecularly imprinted poly (o-aminophenol) film and reduced graphene oxide
decorated with Au nanoparticles composites (rGO-AuNPs). The transmission electron microscope,
cyclic voltammetry, electrochemical impedance spectroscopy and differential pulse voltammetry
were utilized for the characterization of the imprinted polymer film.
Results: Under the optimized experimental conditions, the proposed sensor exhibited two distinct
linear responses ranging from 0.02 to 0.8 μmol L-1 and 0.8 to 10 μmol L-1 towards the concentrations
of FA, and the detection limit was found to be 2.8 nmol L-1 (S/N=3). The molecularly imprinted
film proposed was also found to exhibit comparatively high selectivity toward folic acid
against structurally similar analogues, and the preparation of the sensor was simple and reproducible.
Conclusion: In this work, a molecularly imprinted film fabricated on an rGO-AuNPs modified
electrode was developed for the sensitive and selective determination of FA. Furthermore, the
method was applied to the detection of FA in infant formula milk, multivitamin tablets and blood
serum sample with satisfactory results.