A highly structured 1,10-phenanthroline arrayed hydrophobic sulfone membrane platform for the rapid determination and speciation of Fe 2+ /Fe 3+ ions in water

Abstract

An optical assay for the rapid determination and chemical speciation of Fe 2+ /Fe 3+ 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 Fe 3+ ions in synthetic samples after reduction to Fe 2+ using SO 2 . 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 2+ /Fe 3+ 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.