Newly selective electrochemical sensors for trace-level determination of Al(III) ions in drainage water, spiked tap water and pharmaceutical preparation samples

In this work, two newly sensitive and selective Al(III)-modified carbon paste electrodes (MCPEs) were developed based on diphenylcarbazone (DPC) modifier mixed with tricresyl phosphate plasticizer and either graphite powder (electrode I) or graphite powder mixed with graphene (electrode II). The potentiometric performance characteristics of the two electrodes were scrutinized and discussed. The proposed sensors showed a high electrochemical response in the linear concentration range of 1.0 × 10⁻⁶ to 1.0 × 10⁻² mol L⁻¹ with a good Nernstian slopes of 20.12 ± 0.30 mV decade⁻¹ and 20.63 ± 0.66 mV decade⁻¹ and limits of detection of 9.0 × 10⁻⁷ and 8.5 × 10⁻⁷ mol L⁻¹ for electrode (I) and electrode (II), respectively. Both electrodes showed a fast response time and reasonable thermal stability. The potentiometric response of the DPC-based electrodes was independent on the pH of the tested solutions in ranges of 2.5–5 and 2.5–5.5 for electrode (I) and electrode (II), respectively. The two electrodes can be also used in partially non-aqueous medium containing up to 20% (v/v) acetone or methanol with no significant changes in the working concentration ranges or the slopes. The proposed electrodes showed fairly good discriminating ability toward Al(III) ions in comparison with many other metal ions. The electrodes were applied successfully for Al(III) ions determination in drainage water, spiked tap water and pharmaceutical preparation samples. Furthermore, the electrode surfaces were characterized using energy-dispersive X-ray (EDX) and scanning electron microscopic (SEM) as surface characterization techniques and Fourier Transform Infrared (FT-IR) technique to confirm the interaction between Al(III) and DPC.