Potential stability improvement in solid-contact Pb2+ion-selective electrodes by using polyaniline/montmorillonite composites as the ion-to- electron transducer

This work demonstrates a sensitive and stable solid contact ion selective electrode (SC-ISE) constructed using a polyaniline intercalated hydrophobic montmorillonite composite (PANI-DMT) as a solid transduction layer for the detection of lead ions. A detection limit of 1.0 x 10-7 M and fast potential response (<5 s) were realized using the GC/PANI-DMT/Pb2+-ISM. In addition, the Pb2+ ISE based on PANI-DMT exhibited high stability and E0 reproducibility (+/- 0.6 mV). The potential drift of GC/PANI-DMT/Pb2+-ISM under +/- 1 nA constant current and open circuit potential was as low as (9.4 +/- 4.6) x 103 mu V/h and 25.3 +/- 3.5 mu V/h, respectively. The out-standing stability and reproducibility of GC/PANI-DMT/Pb2+-ISM is attributed to an effective ion diffusion channel provided by DMT, the larger specific capacitance (465 mu F), and improved hydrophobicity of PANI-DMT composites compared to PANI. Importantly, the GC/PANI-DMT/Pb2+-ISM was stable under the external interference of O2, N2, and light, suggesting promise for Pb2+ detection in various applications.