OMC/GCE has been fabricated and used for electrochemical determination of FA as a sensor. The modified electrode displays high sensitivity in the voltammetric measurements of FA in the neutral solutions, and a lower detection limit was obtained. Furthermore, OMC/GCE presented excellent selectivity and satisfying recoveries in detecting FA from vitamin tablets and urine. In conclusion, the OMC/GCE, simple and practical, can be a good electrochemical sensor for the direct determination of FA.