The direct electrochemistry of folic acid at a 2-mercaptobenzothiazole self-assembled gold electrode

A pair of well-defined redox waves of folic acid at a 2-mercaptobenzothiazole self-assembled gold electrode (MBT/SAM/Au) was achieved. Folic acid can bind strongly to MBT/SAM/Au and form a closely packed monolayer, whose average electron transfer rate is 0.085 s−1 with a two-electron/two proton transfer, a maximum surface coverage of 2.8×10−10 mol cm−2, an adsorption equilibrium constant of (4.0±0.2)×105 l mol−1, and an electrode reaction resistance of 12489 Ω. The oxidation peak currents achieved on MBT/SAM/Au vary linearly with the logarithm of the content of folic acid in the range of 8.0×10−9–1.0×10−6 mol l−1. The detection limit is 4.0×10−9 mol l−1. This can be used to determine folic acid.