Lead-selective poly(vinyl chloride) membrane electrodes based on acyclic dibenzopolyether diamides

Area of Science:

• Electrochemistry
• Analytical Chemistry
• Materials Science

Background:

• Ion-selective electrodes (ISEs) are crucial for monitoring heavy metal ions.
• Developing highly selective and sensitive ISEs for lead (Pb2+) detection remains a challenge.
• Dibenzopolyether diamides offer potential as ionophores in ISE membranes.

Purpose of the Study:

• To design and synthesize novel lipophilic acyclic dibenzopolyether diamides as ionophores for Pb(2+)-selective electrodes.
• To evaluate the performance of these ionophores in polymeric membrane ISEs.
• To assess the potentiometric selectivity and response characteristics of the developed ISEs.

Main Methods:

• Synthesis of 12 novel dibenzopolyether diamide compounds.
• Fabrication of solvent polymeric membrane ion-selective electrodes (ISEs) using the synthesized ionophores.
• Potentiometric measurements to determine the linear response concentration range and selectivity coefficients.
• Evaluation of ISE performance for Pb(2+) detection in the presence of interfering ions.

Main Results:

• The ISE based on dibenzopolyether diamide 9 exhibited a linear response for Pb(2+) from 3 x 10(-2) to 1 x 10(-6) M with a slope of 28.5 mV decade(-1).
• All synthesized ISEs demonstrated high selectivity for Pb(2+) over other heavy metal cations (e.g., Cu(2+), Fe(2+), Ni(2+)) and alkali/alkaline earth metal cations.
• Compound 9, featuring an ethylene glycol spacer and N,N-diethyl group, showed superior selectivity for Pb(2+) compared to other tested ionophores.

Conclusions:

• Novel dibenzopolyether diamides are effective ionophores for developing Pb(2+)-selective electrodes.
• The ISE based on compound 9 offers excellent sensitivity, selectivity, and a broad linear response range for lead detection.
• These findings highlight the potential of tailored dibenzopolyether diamides in advanced electrochemical sensing applications for heavy metals.