Electrochemical sensors

>>> Benzene Diazonium Sulfonate Modified Nanoporous Gold Electrodes for the Direct Detection of Copper(II) Ions

We have demonstrated that NPG, which exhibits a natural biofouling resistance, is a suitable material for the detection of trace trace concentrations of copper. The average pore size of NPG affects the sensitivity of the sensor. The linear response range of the electrode could be changed by altering the available surface area. Surface modification of NPG with sulfonate functional groups was performed with SAM formation and by electrografting of benzene diazonium sulfonate. Sodium 3-mercapto-1-propane-

sulfonate modified NPG electrodes displayed high sensitivity and low limits of detection for Cu²⁺. However the gold-thiol bond is less stable than the carbon-gold bond. With the former, changes in the response were obtained with multiple uses. In contrast, benzene diazonium sulfonate modified NPG showed no change after multiple cycles. The linear response (0.2–25 μM) encompassed the legal concentrations (UnitedStates, EPA) of Cu in drinking water (20.5μM, 1300ppb).The sensor was tested in a range of water samples(tap, rain and river water). The results obtained compared well with results obtained from atomic adsorption spectroscopy experiments, while the copper concentrations in rain and river water were too low to be determined by AAS. The test of the combined biofouling protection of the BDS surface modification and the nanoporous structure enabled the accurate determination of Cu²⁺ in artificial serum. The copper sensor described here compares very favourably and could be used in place of atomic adsorption spectroscopy experiments.