A novel procedure of dual direct immersion single-drop microextraction (DDI-SDME) was developed for the sequential separation and preconcentration of Fe(III) and Fe(II) followed by graphite furnace atomic absorption spectrometry determination. At pH 1.5, Fe(III) can selectively react with N-benzoyl-N-phenylhydroxylamine (BPHA) to form the hydrophobic complexes which can be extracted into one organic drop, while Fe(II) remained in the solution. Then, another organic drop containing BPHA was immersed in the sample solution after the extraction of Fe(III) for the preconcentration of Fe(II) at pH ...
