Flame atomic absorption spectrometric determination of μg amounts of Fe (III) ions after solid phase extraction using modified octadecyl silica membrane disks

A simple, rapid and reliable method has been developed to selectively separate and concentrate ultra trace amounts of Fe (III) ions from aqueous samples for the measurement by flame atomic absorption spectrometry (FAAS). By the passage of aqueous samples through an octadecyl silica membrane disk modified by a recently synthesized Schiff base (Bis-(4-nitro phenyl azo) salisilidine-1,3-diamino propane), Fe(III) ions adsorb quantitatively and most of matrix elements will pass through the disk to drain. The retained iron ions are then stripped from the disk by minimal amount of 0.1 mol l− 1 sulfuric acid as eluent. Extraction efficiency and the influence of pH, flow rates, amount of ligand, type and least amount of stripping acid as eluent were evaluated. The recovery of the iron from aqueous solution on the membrane disk modified with 3 mg Schiffʹs base was quantitative over pH 2–4.5. near dynamic range of the proposed method for Fe (III) ions was found in a wide concentration range of 0.20 (± 0.05)–680 (± 2) μg l− 1. The detection limit and preconcentration factor of this solid phase extraction method were found 20.0 (± 0.7) ng l− 1 and 100 respectively. The reproducibility of the procedure is at the most 1.5%.