Porous three-dimensional poly(3,4-ethylenedioxythiophene)/K3Fe(CN)6 network as the solid contact layer in high stability Pb2+ ion-selective electrodes

Abstract

A novel Pb2+ ion-selective electrode (Pb2+-ISE) is reported, in which a micro/nano porous 3D poly(3,4-ethylenedioxythiophene)/K3Fe(CN)6 (PEDOT-PF3) redox active network served as the solid-contact (SC) layer. The obtained GC/PEDOT-PF3/Pb2+-ISE showed a very fast response, high potential stability (drift of only 3.2 μV s−1 at an applied constant current of ± 1nA), good sensitivity with a Nernstian response over the Pb2+ concentration range (10-8 −10-3 M), and a detection limit ∼ 1.66 × 10-9 μg/L. The superior potential stability of GC/PEDOT-PF3/Pb2+-ISE compared to a control electrode prepared simply with a PEDOT SC layer (i.e. GC/PEDOT/Pb2+-ISE), is ascribed to the larger capacitance, lower charge transfer resistance and superior film forming properties of the porous PEDOT-PF3 SC layer. Furthermore, the developed Pb2+-ISE possessed good potential stability with a diminished water layer and no obvious interferences from light, N2, O2 or CO2. Finally, GC/PEDOT-PF3/Pb2+-ISE was applied to the detection of Pb2+ in laboratory waste samples, with the results obtained consistent with those obtained by atomic absorption spectrophotometry (AAS) on the same samples.