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

An optical assay for the rapid determination and chemical speciation of Fe/Fe 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) and linear dynamic range (1 - 100 μg mL) were achieved. The proposed method was also successfully applied for indirect determination of Fe ions in synthetic samples after reduction to Fe using SO. 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 Fe/Fe 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.