Electrochemical and Catalytic Investigations of Homocysteine Using Multiwall Carbon Nanotubes Paste Electrode as a Sensor and Methyldopa as a Mediator

A sensitive and selective electrochemical sensor for the determination of homocysteine (HCy) was developed using a modified multiwall carbon nanotubes paste electrode (MWCNTPE) in the presence of methyldopa (MDOP) as a mediator. This modified electrode showed very efficiency electrocatalytic activity for the anodic oxidation of HCy. Under the optimized conditions, the electrocatalytic peak current showed linear relationship with HCy concentration in the range of 0.1 – 800.0 µmol L -1 with a detection limit of 0.06 µmol L -1 HCy. The relative standard deviations for six successive assays of 1.0 and 15.0 µmol L -1 HCy were 2.1% and 2.6%, respectively. Finally, the modified