Selective and sensitive lead (II) solid-contact potentiometric sensor based on naphthalene-sulfonamide derivative

A new naphthalene-sulfonamide (NS) derivative has been used as ionophore to construct the polyvinylchloride-based lead (II) solid-contact (SC) coated graphite electrode modified with conducting polymer poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate (PEDOT/PSS). The lead-NS derivative complex shows 1:1 stoichiometry with the maximum stability constant of 5.75 as compared to other metal ions that is determined by sandwich membrane method. The proposed membrane morphology has been analyzed by scanning electron microscopy. The proposed lead (II) SC-PEDOT/PSScoated graphite electrode-1 (Pb(II) SC-PEDOT/PSS-CGE- 1) shows the detection limit of 5.62 × 10^-8 M (56.2 nm) with Nernstian slope of 29.21 mV/decade within the pH range of 2.0–7.0 and exhibits small response time of <10 s. It has been used as indicator electrode for the potentiometric titration of lead (II) with ethylenediaminetetraacetic acid and successfully applied for the determination of lead (II) ions content in various environmental and ayurvedic medicines sample matrices with very good performance (0.999 correlation coefficients in the comparison against atomic absorption spectroscopy method).

Keywords
Naphthalene-sulfonamide; Coated graphite electrode; Stability constant; Scanning electron microscopy; Environment