Recovery of nanomolar detection limit of solid-contact lead (II)-selective electrodes by electrode conditioning

Solid-contact Pb2+-selective electrodes (Pb2+-ISEs) were prepared by using polybenzopyrene doped with eriochrome black T as solid contact material and a conventional polyvinyl chloride membrane with lead ionophore IV as selective compound. Nernstian response down to 10(-9) mol dm(-3) Pb2+ was obtained by careful control of the electrode conditioning process. Furthermore, the response at lowest concentrations was retained by exposing the solid-contact Pb2+-ISEs to a solution containing Na(2)EDTA. Finally, the solid-contact Pb2+-ISEs were used in the determination of lead in a synthetic sample (pPb(2+) = 7.40). The analysis of the sample was done with direct potentiometry (pPb(2+) = 7.64 +/- 0.11) and single standard addition method (pPb(2+) = 7.27 +/- 0.07). These results were in good agreement with those obtained by inductively coupled plasma-mass spectrometry (pPb = 7.34). The renewable response of the Pb2+-ISEs at low concentrations opens interesting possibilities when dealing with trace-level measurements of Pb2+.