Disposable multi-walled carbon nanotubes-based plasticizer-free solid-contact Pb²⁺-selective electrodes with a sub-ppb detection limit

Potentiometric plasticizer-free solid-contact Pb²⁺-selective electrodes based on copolymer methyl methacrylate-n-butyl acrylate (MMA-BA) as membrane matrix and multi-walled carbon nanotubes (MWCNTs) as intermediate ion-to-electron transducing layer have been developed. The disposable electrodes were prepared by drop-casting the copolymer membrane onto a layer of MWCNTs, which deposited on golden disk electrodes. The obtained electrodes exhibited a sub-ppb level detection limit of 10^-10 mol·L^-1. The proposed electrodes demonstrated a Nernstian slope of 29.1 ± 0.5 mV/decade in the linear range from 2.0 × 10^-10 to 1.5 × 10^-3 mol·L^-1. No interference from gases (O₂ and CO₂) or water films was observed. The electrochemical impedance spectroscopy of the fabricated electrodes was compared to that of plasticizer-free Pb²⁺-selective electrodes without MWCNTs as intermediated layers. The plasticizer-free MWCNTs-based Pb²⁺-selective electrodes can provide a promising platform for Pb(II) detection in environmental and clinical application.