Disposable Multi-Walled Carbon Nanotubes-Based Plasticizer-Free Solid-Contact Pb2+-Selective Electrodes with a Sub-PPB Detection Limit †

Abstract

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.

Potentiometric Sensing

“…After one month of storage, the electrodes demonstrated a close to Nernstian response slope with a detection limit increased by only half an order of magnitude. The same research group used this surfactant-free approach to prepare a Pb 2+ -selective electrode based on MWCNTs as a transducer and copolymer methyl methacrylate- n -butyl acrylate as a membrane matrix . In this case, the MWCNT suspension was prepared in the presence of NPOE and deposited directly onto the electrode surface, while the plasticizer-free membrane matrix was drop-cast on top of the transducer layer.…”

“…The same research group used this surfactant-free approach to prepare a Pb 2+ -selective electrode based on MWCNTs as a transducer and copolymer methyl methacrylate-n-butyl acrylate as a membrane matrix. 83 In this case, the MWCNT suspension was prepared in the presence of NPOE and deposited directly onto the electrode surface, while the plasticizer-free membrane matrix was drop-cast on top of the transducer layer. The proposed electrodes gave a Nernstian slope of 29.1 ± 0.5 mV/ decade in the linear range from 2.0 × 10 −10 to 1.5 × 10 −3 M with a detection limit of 1.0 × 10 −10 M. The absence of interference from light, gases (O 2 , CO 2 ), or the water layer formation on the performance of the sensor was confirmed.…”

Modern Electrode Technologies for Ion and Molecule Sensing

“…As a lone material, CNTs do not make for a robust macrostructure. As a result, they are often used as a modification or component in an electrode rather than being utilized in a standalone fashion [17,31,33,[38][39][40][41][42]. The ends of CNTs can be capped with fullerene-like structures or can be modified with functional groups, which opens opportunities for selectivity and further modification [35,37].…”

“…CNTs have been incorporated into electrode designs by inclusion in a binder, drop-coating, forming a paste similar to carbon paste, and formation of composite materials that include CNTs [17,31,33,38,39]. The tubes are typically randomly aligned.…”

Optimization of Castor Oil-Based Ion Selective Electrode (ISE) with Active Agent 1,10-Phenanthroline for Aqueous Pb2+ Analysis

“…Potentiometry could be an alternative for Pb analysis, in which this method could measure low concentrations, have properties of being cheap and accurate, and does not require sample pre-treatment [ 10 ]. Parts of the equipment used for the Pb detection is ion selective electrode (ISE Pb 2+ ).…”