Simultaneous flow-injection determination of iron(II) and total iron by micelle enhanced luminol chemiluminescence Original Research Article

A flow-injection method is proposed for the determination of iron(II) and for the simultaneous determination of iron(II) and total iron based on the catalytic effect of iron(II) on the oxidation of luminol with hydrogen peroxide in an alkaline medium. The activating effect for the catalysis of iron(II) was extremely exhibited in the presence of citric acid, while citric acid acted as a masking agent for iron(III). Furthermore, the sensitivity of the method was enhanced by adding tetradecyltrimethylammonium bromide (TTAB) as a cationic surfactant together with citric acid. The iron(III) in sample solution can be determined by passing through the silver reductor column introduced in the FIA system to reduce iron(III) to iron(II), which allows total iron determination. Calibration graphs for iron(II) and total iron were linear over the range 5×10−9–1×10−6 mol dm−3 at a rate of 18 samples h−1 (36 peaks h−1). The relative standard deviations (n=10) for 4×10−8 mol dm−3 iron(II) and 1×10−7 mol dm−3 total iron were 3.0% and 1.5%, respectively. The proposed method was successfully applied to the determination of iron in human hair (NIES, no. 5) and natural waters.