Application of a Single-Wall Carbon Nano-Tube Film Electrode to the Determination of Trace Amounts of Folic Acid

Single-wall carbon nano-tubes were used to modify the surface of a glassy carbon electrode (GC) and applied in the determination of folic acid with voltammetry. The experiments demonstrated that the presence of a carbon nano-tube film on the electrode greatly increased the reduction peak current of folic acid. Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were used in a comparative investigation of the electrochemical reduction of folic acid with the film electrode. Effects of pH on the peak current and the peak potential were studied in the pH range of 4.0–8.0 with Britton-Robinson buffer solution. The reduction peak current was found to be linearly related to folic acid concentration over the range of 1 × 10⁻⁸ to 1 × 10⁻⁴ mol L⁻¹ with a detection limit of 1 × 10⁻⁹ mol L⁻¹ after 5 min accumulation. The film electrode provides an efficient way for eliminating interferences from some inorganic and organic species in the solution. The high sensitivity, selectivity and stability of the film electrode demonstrate its practical application from a simple and rapid determination of folic acid in tablets.