PPF-1/Ferron-based hybrid sorption–spectrometric method for the sensitive and selective determination of Fe(III)

A novel and highly efficient sorption-spectrometric method has been developed for the selective determination of trace Fe(III) ions in complex aqueous environments. The proposed approach is based on the synthesis of a hybrid sorbent by immobilising the classical analytical reagent Ferron (8-hydroxy-6-iodoquinoline-5-sulphonic acid) onto a polyethylene polyamine-functionalised polyacrylonitrile matrix (PPF-1). The immobilised Ferron significantly enhances the sorptive capacity and selectivity of the solid phase, enabling effective preconcentration of Fe(III) before quantification via flame atomic absorption spectrometry (FAAS). Under optimal conditions (pH 2–3, contact time 2–3 min), the method achieves a high adsorption efficiency (99.7%), a linear range of 5.6–28.0 μg L −1, and a detection limit of 0.28 μg L −1. Spectrophotometric, FTIR, X-ray fluorescence, SEM and diffuse reflectance spectroscopy confirmed the formation of a stable Fe(III)-Ferron complex on the sorbent surface. Interference studies demonstrated the high selectivity of the method towards Fe(III) in the presence of common matrix ions such as Na+, K+, Ca2+, Mg2+, Ba2+, Zn2+, Al3+, Pb2+, Ni2+, Co2+, Hg2+, and Cu2+. The developed method was successfully applied to real samples, including wastewater, industrial water, technogenic water, and tap water. The recoveries ranged from 97% to 99%, specifically 97%–98% for wastewater, 98% for industrial water, 98–99% for technogenic water, and 97% for tap water, demonstrating the accuracy and reliability of the proposed method. This approach offers a cost-effective, rapid, and green alternative for routine monitoring of Fe(III) in environmental and industrial water systems.