Bismuth film microelectrode modified with overoxidized poly-1-naphtylamine protective membrane for enhanced stripping voltammetric detection

The application of protective overoxidized poly-1-naphtylamine membrane (ONAP) is demonstrated in combination with bismuth film microelectrode (ONAP-BiFME) for anodic stripping voltammetric measurement of trace heavy metals in the presence of some selected surfactants. The ONAP membrane was electrochemically deposited on the surface of bare single carbon fiber microelectrode followed by the in situ or ex situ preparation of the bismuth film. The key operational parameters influencing the stripping performance of the ONAP-BiFME were optimized and its electroanalytical performance was examined in the model solution containing Cd(II) and Pb(II) as test metal ions. The ONAP-BiFME exhibited significantly enhanced stripping voltammetric response (approximately 70% for Cd(II) and 45% for Pb(II)) in comparison with unmodified BiFME in the absence of surfactants. In the presence of high concentrations, e.g., 20 mg L-1, of anionic or cationic surfactants, the stripping signal for, e.g., Cd(II) decreased for less than 6% at the ONAP-BiFME, whereas at the unmodified BiFME the signal attenuated considerably (approximately 38%). Moreover, in the presence of 10 mg L-1 of nonionic surfactant Triton X-100, the stripping signals at the bare BiFME were almost completely suppressed, whereas at the ONAP-BiFME exhibited linear concentration behavior in the examined concentration range from 10 to 1.20 mu g L-1, with the calculated limit of detection of 5.0 mu g L-1 and 3.4 mu g L-1 for Cd(II) and Pb(II), respectively in connection with 60s accumulation time. The attractive behavior of ONAP-modified BiFME expands the applicability of bismuth-based electrodes for measurement of trace heavy metals in real environments, where the presence of more complex matrix can be expected.