Spectrophotometric Quantitatification of Fe(II) and Fe(III) Ions Using N,N'-bis(4-methoxysalicylidene) phenylendiamine

Abstract

A novel N2O2 Schiff base ligand, N,N'-bis(4-methoxysalicylidene)phenylendiamine(4-CH3O-Salphen), has been synthesized. It has been revealed that the compound is very useful for the spectrophotometric quantification of Fe(II) and Fe(III) ions in aqueous solutions, such as mineral water, hot spring water, sea water, and waste water. The optimum conditions for the quantitative analysis are the followings; [4-CH3O-Salphen]=4.0×10 -4 M, DMF/H2O=70/30(v/v), pH=3.4~3.8, T= at 55 o C, and prereaction time=1.0 hr. The sample of single valence state was prepared by the preliminary oxidation or reduction using H2O2 (5.0×10 -4 M) and NH2OH•HCl (5.0×10 -4 M). The quantitative analyses of Fe(II) and Fe(III) ion were performed by measuring the absorbance at 434 nm and 456 nm, respectively. The estimated mean values agreed well with the standard values within the range of 2.00~6.90%. The limit of detection was 27.9 ng/mL for Fe(II) and 55.8 ng/mL for Fe(III).