Spectrophotometric Determination of Iron(II) with 2-Diethylamino-4-hydroxy-5-nitroso-6-aminopyrimidine

Abstract

2-Diethylamino-4-hydroxy-5-nitroso-6-aminopyrimidine (EHNA) is synthesized and used for the spectrophotometric determination of iron(II). EHNA reacts easily with iron(II), copper(II) or nickel(II) to form water-soluble complexes at pH 6.1. The iron(II)-EHNA complex, once formed, is stable even at pH 10.3, while the copper(II) and nickel(II) complexes are decomposed at this pH. The iron(II)-EHNA complex is extracted into an organic solvent such as isopentyl alcohol. The molar absorptivity of the iron(II) complex in an aqueous solution is 3.0×10⁴1 mol⁻¹ cm⁻¹ at 660 nm. The molar ratio of iron(II) to EHNA in the complex is 1:3, according to the continuous variation method. This method has been satisfactorily applied to the determination of iron in various samples, such as leaded brass, copper-nickel and magnesium-aluminum alloys.