Characterization and performance of aluminum (III)-complex as an active material for potentiometric sensor

Aluminum is the third most abundant element in the Earth's crust. It becomes more soluble and available when the soil pH falls below 5. Consequently, elevated aluminum concentrations can severely inhibit plant root growth, causing stunted roots and a reduced ability to absorb water and nutrients. Therefore, monitoring aluminum levels in soil is important, which has led to significant interest in developing sensors for its detection. Al(III)-flubendazole complex (Al-FLU) was synthesized for the first time and evaluated as a potential electroactive sensing material. This complex was incorporated into a novel, well-defined chemically modified carbon paste electrode (CPE). Tricresyl phosphate (TCP) was selected from three tested plasticizers and used as a solvent mediator in the paste matrix, complementing the Al-FLU complex. This plasticizer improved the electrode's mechanical stability and analytical performance. With an optimal composition, the resulting electrode achieved the intended Nernstian slope of 20.0 ± 0.683 mV per decade for trivalent cations over the concentration range 1.0 × 10⁻⁷ to 1.0 × 10⁻¹ mol L^-1, with a detection limit of 1.0 × 10⁻⁷ mole L^-1 and a response time of about 5.0 s. The electrode demonstrated good selectivity, sensitivity, reversibility, repeatability, and reproducibility. Its potential response remained constant across the pH range of 3.4-5.5 at room temperature (25 ± 1 °C). The thermal stability of the electrode was also evaluated between 10 and 60 °C. Therefore, this optimally formulated electrode can be used to establish a simple direct potentiometric analytical method for the systematic quantification of Al(III) in both pure solutions and various real samples.