Chelating ionophore based membrane sensors for copper(II) ions

Area of Science:

• Analytical Chemistry
• Materials Science

Background:

• Copper(II) chelation with acetylacetone, ethylacetoacetate, and salicylaldehyde yields highly stable complexes.
• Polyvinyl chloride (PVC) based membranes are widely used in ion-selective sensors.

Purpose of the Study:

• To investigate the efficacy of PVC-based membranes incorporating bis[acetylacetonato] Cu(II), bis[ethylacetoacetate] Cu(II), and bis[salicyldehyde] Cu(II) as copper(II) selective sensors.
• To optimize sensor performance through the addition of sodium tetraphenylborate and various plasticizers.

Main Methods:

• Fabrication and characterization of PVC-based membranes incorporating three different copper(II) chelates.
• Optimization of membrane composition using plasticizers like TBP and NaTPB.
• Potentiometric measurements to evaluate sensor response, linearity, detection limit, pH range, response time, and selectivity.

Main Results:

• The membrane composition of 1% bis[acetylacetonato] Cu(II): 33% PVC: 65% TBP: 1% NaTPB demonstrated optimal performance.
• The sensor exhibited a linear potential response to Cu(II) over a wide concentration range (2.0x10^-6 to 1.0x10^-1 M) with a detection limit of approximately 0.1 ppm.
• The sensor showed Nernstian compliance (29.3 mV/decade) between pH 2.6 and 6.0, with a fast response time of ~9 seconds and excellent selectivity for Cu(2+) over interfering cations.

Conclusions:

• The developed PVC-based membrane sensor incorporating bis[acetylacetonato] Cu(II) offers a robust and selective method for copper(II) detection.
• The sensor's performance, including its wide linear range, low detection limit, and fast response, makes it suitable for practical applications.
• The sensor was successfully applied in potentiometric titrations of Cu(II) with EDTA and in the determination of copper in real samples like vegetable foliar and multivitamin capsules.