Detection of homocysteine at carbon nanotube paste electrodes

The use of a carbon-nanotube paste (CNTP) electrode provides an effective means for the determination of homocysteine. A decrease of ca. 120 mV in the overpotential for the oxidation of homocysteine compared to a traditional carbon paste electrode, is reported along with greatly enhanced signal-to-noise characteristics. The analytical parameters have been assessed with a linear range from 5 to 200 μM and a detection limit of 4.6 μM. Furthermore, the generic nature of this increased reactivity of the CNTP surface towards thiol moieties has been demonstrated with cysteine, glutathione and n-acetylcysteine, providing a greatly enhanced electrochemical response compared to the carbon paste electrode.