Stable Pb(II) ion-selective electrodes with a low detection limit using silver nanoparticles/polyaniline as the solid contact

Solid contact-based ion-selective electrodes (SC-ISEs) based on silver nanoparticles/polyaniline (Ag@PANI) as the solid contact (SC) were successfully prepared. The Ag@PANI SC showed high capacitance and excellent electron transport performance. Owing to the synergetic effects of the Ag nanoparticles and PANI, a GC/Ag@PANI-II/Pb2+-ISE (where II refers to a Ag content of 0.01 wt% in the SC layer) showed a low Pb2+ detection limit (6.31 x 10(-10) M) with a slope of 29.1 +/- 0.3 mV/dec, a fast response (< 5 s), and high stability. GC/Ag@PANI-II/Pb2+-ISE exhibited a Nernstian response for Pb2+ ions over a wide concentration range (10(-3) to 10(-9) M). After a 3-week operation, GC/Ag@PANI-II/Pb2+-ISE responded linearly to Pb2+ over the range of 10(-7)-10(-3) M, demonstrating good long-term potential stability. Furthermore, the electrode showed excellent reproducibility and repeatability of the potential values and was successfully applied to detect the Pb2+ concentration in real samples with a recovery of 97 - 109%. Results suggest that Ag@PANI composites offer good transducer performance in trace ion detection sensors.