Novel Ionophore for Aluminum Ion Sensors: Synthesis and Analytical Characterization

A new and rapid potentiometric method to quantify aluminum ions concentration was developed. The method involves the development of an aluminum ion sensor with a membrane consists of diethyl (2-azobenzoic acid) malonate (DAM) as a novel ionophore in poly (vinyl chloride) matrix membrane plasticized with orthonitrophenyl-octyl ether or dioctylphthalate. The structure of the synthesized ionophore (DAM) was identified using Fourier transform infrared, 1 H Nuclear magnetic resonance, and elemental analysis. The proposed electrode reveals a Nernstian response over Al 3+ ion in a concentration range $1\times 10^{\mathrm {-7}}$ – $1\times 10^{\mathrm {-2}}$ mol $\text{L}^{\mathrm {-1}}$ with the cationic slopes of 19.6 ± 0.3 and 19.3 ± 0.2 mV decade $^{\mathrm {-1}}$ , and the limits of detection $5 \times 10^{\mathrm {-8}}$ and $7 \times 10^{\mathrm {-8}}$ mol $\text{L}^{\mathrm {-1}}$ aluminum(III) for orthonitrophenyl-octyl ether and dioctylphthalate-based membrane sensors, respectively. The electrodes showed good discrimination toward Al 3+ ion in the presence of the most common cations. The electrodes show response in a short time (10 s) for the entire concentration range and used for 11 weeks without significant variation in potentials. To evaluate the application of the investigated electrodes was used to determine Al 3+ ion at different collected samples from environmental sources. In addition, these sensors have been used as indicator electrodes in the potentiometric titration of Al 3+ ion against Ethylenediaminetetraacetic acid.