Analytical Sciences

A Highly Structured 1,10-Phenanthroline Arrayed Hydrophobic Sulfone Membrane Platform for the Rapid Determination and Speciation of Fe²⁺/Fe³⁺ Ions in Water

Liyakat Hamid MUJAWAR,*1 Muhammad Imtiaz RASHID,*1,*2 Zulfiqar Ahmad REHAN,*3 Talal ALMEELBI,*1 Jalal Mohammad BASAHI,*1 and Mohammad Soror EL-SHAHAWI*4,*5

*1 Center of Excellence in Environmental Studies, King Abdulaziz University, P. O. Box 80200, Jeddah 21589, Saudi Arabia
*2 Department of Environmental Sciences, COMSATS Institute of Information Technology, 61100, Vehari, Pakistan
*3 Center of Excellence in Desalination Technology, King Abdulaziz University, P. O. Box 80200, Jeddah 21589, Saudi Arabia
*4 Department of Chemistry, Faculty of Science, King Abdulaziz University, P. O. Box 80203, Jeddah 21589, Saudi Arabia
*5 On sabbatical leave from the Department of Chemistry, Faculty of Sciences, Damiatta University, Damiatta, Egypt

An optical assay for the rapid determination and chemical speciation of Fe²⁺/Fe³⁺ species has been proposed for the first time on a polyether sulfone (PES) membrane platform. The small pore size and low wettability (θ ∼82°) of the membrane disallowed the dissipation of analyte droplets on the surface, thus localizing it onto nanoliter arrayed 1,10-phenanthroline spots. Under optimized conditions and within ∼5 min, an acceptable limit of detection (0.1 μg mL⁻¹) and linear dynamic range (1 – 100 μg mL⁻¹) were achieved. The proposed method was also successfully applied for indirect determination of Fe³⁺ ions in synthetic samples after reduction to Fe²⁺ using SO₂. The performance of the proposed sensor was validated for its robustness and stability. Due to high selectivity and accuracy, the method was satisfactorily applied for the analysis of Fe²⁺/Fe³⁺ species in marine water samples. The proposed method is an easy and low-cost system coupled with good reproducibility and ruggedness, applicable for point-of-use testing.

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