Simple cast-deposited multi-walled carbon nanotube/Nafion (TM) thin film electrodes for electrochemical stripping analysis

A stable composite film of multi-walled carbon nanotubes (MWNTs) with a Nafion (TM) cation exchanger membrane is prepared using a simple and reproducible cast deposition methodology. The MWNTs are cylindrical with diameters in the range of 40-60 nm and a length of up to several micrometers. They provide sufficiently high electrical conductivity across the film. Nafion (TM) acts both as a binder for the carbon structure and selectivity introducing matrix as shown by voltammetric experiments with the Fe(CN)(6)(3-/4-) redox system. The anodic stripping responses for Cd and Pb metal accumulated from a solution of 0.2-1 mu M in 0.1M acetate buffer are demonstrated and optimized. The limit of detection under these conditions is typically 51 nM. The feasibility of using the MWNTs/Nafion (TM) thin film electrode for the anodic stripping voltammetric determination of cadmium and lead in 0.1M acetate buffer in the presence of surfactants/interferents is examined. Sodium dodecyl sulfate (SDS), Triton X-100 (TX-100), dodecyl pyridinium chloride (DPC), and bovine serum albumin (BSA) were examined as four typical interferents. Relatively small enhancing and suppressing effects on the stripping peak currents for Cd and for Pb detection at the MWNTs/Nafion (TM) film modified electrode were observed. The MWNTs/Nafion (TM) thin film electrode performed very well even in the presence of the cationic surfactant DPC and could in future be of wider applicability.