Flow injection analysis spectrophotometric speciation of iron in rain, fog, dust and soil samples

A new attempt for the flow injection analysis (IIA) spectrophotometric speciation of iron in various environmental samples is described. The method is based on conventional iron-thiocyanate colour reaction. In this work, oxidation of Fe(II) into Fe(III) is carried out with HNO 3 solution in the flowing stream and total iron present in the sample is measured. Whereas, Fe(III) is measured with a mixed solution of HCl+H 2 SO 4 . The presence of cationic (CPC) and non-ionic (TX-100) surfactants remarkably enhances the sensitivity (3 fold) of the automated conventional method and make the method applicable for the speciation of iron in real samples (rain, fog) containing the metal in lower ppb levels.